Clinical Chemistry 46: 2050-2068, 2000;
(Clinical Chemistry. 2000;46:2050-2068.)
© 2000 American Association for Clinical Chemistry, Inc.
Diagnosis and Monitoring of Hepatic Injury. II. Recommendations for Use of Laboratory Tests in Screening, Diagnosis, and Monitoring
D. Robert Dufour1,a,
John A. Lott2,
Frederick S. Nolte3,
David R. Gretch4,
Raymond S. Koff5 and
Leonard B. Seeff6
1
Pathology and Laboratory Medicine Service, Veterans Affairs Medical Center, Washington, DC 20422, and Department of Pathology, George Washington University School of Medicine, Washington, DC 20037.
2
Department of Pathology, The Ohio State University
College of Medicine, Columbus, OH 43210.
3
Departments of Pathology and Laboratory Medicine, Emory
University School of Medicine, Atlanta, GA 30322.
4
Department of Laboratory Medicine, University of
Washington School of Medicine, Seattle, WA 98104-2499.
5
Department of Medicine, University of Massachusetts
Medical Center, Worchester, MA 06155.
6
Hepatitis C Programs, National Institute of Diabetes,
Digestive, and Kidney Diseases, National Institutes of Health,
Bethesda, MD 20892, and Georgetown University School of Medicine,
Washington, DC 20037.
a Address correspondence to this author at: Pathology and Laboratory Medicine Service, 113, VA Medical Center, 50 Irving Street NW, Washington, DC 20422. Fax 202-745-8284; e-mail
d.robert.dufour{at}med.va.gov
 |
Abstract
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Purpose: To review information on the use of laboratory tests in
screening, diagnosis, and monitoring of acute and chronic hepatic
injury.
Data Sources and Study Selection: A MEDLINE search was performed
for key words related to hepatic diseases, including acute hepatitis,
chronic hepatitis, alcoholic hepatitis, cirrhosis, hepatocellular
carcinoma, and etiologic causes. Abstracts were reviewed, and articles
discussing use of laboratory tests selected for review. Additional
articles were selected from the references.
Guideline Preparation and Review: Drafts of the guidelines were
posted on the Internet, presented at the AACC Annual Meeting in 1999,
and reviewed by experts. Areas requiring further amplification or
literature review were identified for further analysis. Specific
recommendations were made based on analysis of published data and
evaluated for strength of evidence and clinical impact.
Recommendations: Although many specific recommendations are made
in the guidelines, only some summary recommendations are listed here.
In acute hepatic injury, prothrombin time and, to a lesser extent,
total bilirubin are the best indicators of severity of disease.
Although ALT is useful for detecting acute and chronic hepatic injury,
it is not related to severity of acute hepatic injury and only weakly
related to severity of chronic hepatic injury. Specific tests of viral
markers should be the initial differential tests in both acute and
chronic hepatic injury; when positive, they are also useful for
monitoring recovery from hepatitis B and C.
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Introduction
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This reports represents a continuation of the National
Academy of Clinical Biochemistry Guidelines on Use of Laboratory Tests
in the Diagnosis and Monitoring of Hepatic Injury. Part 1
(1) discusses performance characteristics for laboratory
tests and also describes the methodology used to develop the
guidelines. Table 2
in Part 1 outlines the codes used for
characterizing the recommendations contained in both parts of the
Guidelines.
Hepatocyte injury is common worldwide. Despite a decreased incidence of
acute viral hepatitis since introduction of vaccines for hepatitis A
and B and testing of the blood supply for hepatitis C, almost 100 000
cases occur annually in the United States alone, most of them
undiagnosed. An estimated 1.5% of the US population is chronically
infected with hepatitis B or C virus. Individuals with chronic
hepatitis are at increased risk for cirrhosis and hepatocellular
carcinoma
(HCC),1
the main causes of death from liver disease in Western
countries. Chronic liver diseases are among the more common disorders
seen by physicians. We present here guidelines for the use of
laboratory tests in screening, diagnosis, and monitoring of acute and
chronic hepatic injury.
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Acute Hepatic Injury
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Acute hepatic injury can be recognized by the presence of jaundice
or nonspecific symptoms of acute illness accompanied by increases in
the activities of aspartate aminotransferase (AST; EC 2.6.1.1) and/or
alanine aminotransferase (ALT; EC 2.6.1.2). An estimated 80% of
individuals with acute viral hepatitis are never diagnosed clinically,
although some may be detected by increased aminotransferases in the
face of nonspecific or absent clinical symptoms. AST and ALT activities
are seldom >10 times the upper reference limit in liver diseases other
than acute hepatic injury. Alkaline phosphatase (ALP; EC 3.1.3.1) is
more than three times the upper reference limit in <10% of cases of
acute hepatic injury (2)(3). With the decreasing
incidence of acute viral hepatitis, other liver diseases are more
commonly encountered as causes of increased AST or ALT activities; as
many as 25% of those with AST >10 times the reference limit may have
obstruction as a cause (4). Approximately 1–2% of patients
with bile duct obstruction have transient increases in AST and/or ALT
activities of >2000 U/L (5)(6);
aminotransferase activities usually fall to within reference limits by
10 days even if obstruction persists
(2)(4)(5). The distribution of
direct bilirubin as a percentage of total bilirubin is similar in acute
hepatic injury and obstructive jaundice (7). In patients
with jaundice, only 16% of those with acute hepatic injury have direct
bilirubin <50% of total bilirubin; values below this suggest another
cause for jaundice, such as hemolysis (7). The best
discriminant values for recognizing acute hepatic injury appear to be
200 U/L for AST (sensitivity, 91%; specificity, 95%) and 300 U/L for
ALT (sensitivity, 96%; specificity, 94%) (3). AST is >10
times the upper reference limit in slightly over one-half of patients
at the time of presentation (3). In uncomplicated alcoholic
hepatitis, AST and ALT values are almost never >10 times the upper
reference limit, the AST/ALT ratio is >2 in 80% of cases, and
increased ALP is present in 20% of cases (8)(9)(10)(11)(12). Jaundice
occurs in 60–70% of cases of alcoholic hepatitis
(9)(10). The frequency of jaundice in patients
with acute viral hepatitis differs both by age and etiologic agent.
Jaundice is rare in children with viral hepatitis, and when it is
present is less severe than in adults. In one study, only 1% of
children with acute hepatitis had peak bilirubin >171 µmol/L (10
mg/dL), whereas 27% of adults did (13). In adults, jaundice
develops in 70% of cases of acute hepatitis A (14),
33–50% of cases of acute hepatitis B (15)(16),
and 20–33% of cases of acute hepatitis C
(17)(18). In children, there is a direct
correlation between age and peak serum bilirubin; an increase of 10
years in age is associated with an average increase of 85 µmol/L (5
mg/dL) in bilirubin. In adults, however, there is only a slight
increase or no increase with increasing age (7).
Recommendation:
- Acute hepatic injury can be diagnosed by ALT >10 times the upper
reference limits and ALP <3 times the appropriate upper reference
limit (IIB).
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markers of severity
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Acute viral hepatitis A and B are usually self-limited illnesses,
and most patients recover completely. In those with acute hepatitis C
infection, 
85% develop chronic hepatitis. Rarely, acute hepatic
injury causes severe liver damage and acute liver failure. Testing
should identify patients at highest risk for liver failure.
Aminotransferase activities are related more to the cause of hepatic
injury than to severity (Table 1
). There is weak correlation between aminotransferase activities
and bilirubin in viral hepatitis (3) and none in ischemic
hepatic injury (19). Peak aminotransferase activities bear
no relationship to prognosis and may fall with worsening of the
patient’s condition (20). Prothrombin time (PT) is the most
important predictor of prognosis; PT cutoff times >4 s beyond control
or >20 s, or an international normalized ratio >6.5 identify
patients at high risk of death (20)(21)(22)(23)(24). In alcoholic
hepatitis, PT >5 s beyond control, bilirubin >428 µmol/L (>25
mg/dL), or albumin <25 g/L (2.5 g/dL) in a patient >55 years of age
predicts 90% likelihood of death (10)(25). In
ischemic or toxic hepatic injury, prolongation of PT is common early
after injury; values peak by 24–36 h after injury and then rapidly
return to normal. In acetaminophen injury, marked prolongation
of PT does not by itself indicate likelihood of liver failure
(26)(27), but a persistent increase in or
increasing PT 4 days after acetaminophen ingestion does
(28). Peak bilirubin is not a good indicator of prognosis in
most forms of hepatic injury (20). Total bilirubin >257
µmol/L (15 mg/dL) or PT >3 s above the upper reference limit
(29) in patients with viral hepatitis indicates severe liver
injury and mandates close monitoring for encephalopathy.
Recommendations:
- Total bilirubin >257 µmol/L (15 mg/dL) or PT >3 s above the
upper reference limit in an individual with viral hepatitis, in the
absence of other factors affecting results, indicates severe liver
injury (IIB).
- Direct bilirubin is needed to rule out other causes of increased total
bilirubin, such as hemolysis, but it does not differentiate hepatic
injury from obstructive jaundice (IIB).
- With acetaminophen toxicity, a persistent increase in or increasing PT
>4 days after ingestion indicates severe liver injury (IIB).
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differential diagnosis
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Initial laboratory evaluation of patients with acute hepatic
injury should include a drug history and testing for antibodies to the
hepatitis A, B, and C viruses (HAV, HBV, and HCV), using the Health
Care Financing Administration-approved acute hepatitis panel [IgM
against HAV (IgM anti-HAV) and the HBV core antigen (IgM anti-HBc), HBV
surface antigen (HBsAg), and antibodies against HCV (anti-HCV);
Fig. 1
]. Most hepatic drug reactions occur within 3–4 months of
initiating treatment. However, in some cases, hepatic injury may become
manifest as late as 12 months after treatment is initiated, and in a
few cases injury may become evident days to weeks after the responsible
drug is stopped (30). Hence, it is important to ask about
all drugs the patient may have received or has continued to receive
during the past year or so.
View larger version (33K):
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Figure 1. Evaluation of suspected acute hepatic injury.
Initial evaluation of patients with signs and symptoms such as
jaundice, fever, and right upper quadrant abdominal pain should be by
measurement of aminotransferases. Marked increases (>3000 U/L) of
either enzyme are usually attributable to ischemic or toxic liver
injury; if history is negative for either, then the diagnostic workup
should continue as in persons with smaller increases. Viral serologies
are the principal tests for evaluation of acute hepatic injury,
although the falling incidence of viral diseases has made other causes
proportionally more common. Because both prescription and
nonprescription drugs can cause acute injury, a detailed drug history
is critical, particularly in those with increased ALP. In those with
coexistent increases in ALP, obstruction and other viruses such as EBV
and CMV must be considered as well. ALK, alkaline
phosphatase; Nl, normal.
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IgM anti-HAV, the diagnostic test of choice for acute HAV infection,
disappears by 4–6 months (31), whereas total HAV antibodies
persist for life (32) and are found in a high percentage of
the population (33). Because of its brief period of
transmissibility, diagnosis of acute HAV infection should be made as
soon as possible after presentation, ideally within 48 h, to allow
immune globulin treatment of exposed individuals. IgM anti-HBc and
HBsAg are the most reliable tests for acute HBV infection
(29)(34); IgG (and thus total) anti-HBc persists
for many years (35). Other HBV viral markers and antibodies
are not of use in the diagnosis of acute HBV infection.
There currently is no test to definitively diagnose acute hepatitis C
because anti-HCV and HCV RNA can be present in both acute and chronic
HCV infections. Anti-HCV is detectable with second-generation enzyme
immunoassays in only 57% of acute HCV cases at the time of
initial increases in enzyme activities, whereas HCV RNA is positive in
essentially all cases (36), although it is intermittently
present in 15% (37)(38). By the time of
clinical presentation, 80–90% of cases have detectable anti-HCV
(38). Patterns that would support a diagnosis of acute
hepatitis C are negative anti-HCV but positive HCV RNA, or (if HCV RNA
was not tested) anti-HCV results that convert from negative to positive
within a short period. Use of antibodies to hepatitis D virus
(anti-HDV) to detect delta (HDV) infection should be limited to
patients with positive HBsAg, particularly if accompanied by severe
acute hepatitis, high risk factors (e.g., intravenous drug abuse or
hemophilia), or a biphasic pattern of illness (39). If a
patient with chronic hepatitis B becomes superinfected with HDV, a
clinical picture resembling severe acute hepatic injury and hepatic
failure may evolve (39).
Recommendations:
- Initial evaluation of acute hepatic injury should include a detailed
drug history and viral markers (IgM anti-HAV, IgM anti-HBc, HBsAg, and
anti-HCV; IIB).
- Because of the need for postexposure prophylaxis, turnaround time of
IgM anti-HAV should be <48 h (IIIC and IIIE).
- If cost-effective (based on prevalence), laboratories may use total
antibody to HAV and anti-HBc initially, performing IgM antibodies only
if one or both is positive, if the turnaround time needs can be met
(IIIE).
- Diagnosis of acute HCV infection (in a patient with a clinical picture
of acute hepatic injury) can be presumptively made by negative HAV and
HBV markers, recent exposure, and either negative anti-HCV and positive
HCV RNA or negative anti-HCV at initial presentation with development
of positive anti-HCV within 1–3 months (IIIB).
- Testing for HDV should be limited to patients with positive HBsAg,
atypical clinical course, and high risk for HDV infection (IIB and
IIE).
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workup of patients without obvious cause for acute hepatic
injury
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Ischemic and toxic hepatic injury.
AST or ALT values
>100-fold higher than normal are rare in viral hepatitis
(2)(3) but common in both toxin ingestion,
especially acetaminophen
(27)(40)(41), and ischemic hepatic
injury (19)(26)(42). In
acetaminophen-induced hepatic injury, peak AST is >3000 U/L in 90% of
cases (41), a value virtually never seen with acute viral
hepatitis (3). Toxic or ischemic hepatic injury is the cause
of >90% of cases of acute hepatic injury with AST activity >3000 U/L
(43). In both ischemic and acetaminophen hepatic injury, AST
and ALT activities typically peak early (often in the first 24 h
after admission) with AST activity initially higher than that of ALT.
After peaking, activities of both fall rapidly. AST may fall by 50% or
more in the first 24 h (40)(41), and it
declines more rapidly than ALT because of its shorter half-life
(3); AST activity reaches near normal values an average of 7
days after injury (2). PT is >4 s above the reference
limits in 90% of cases (26)(27) and falls
rapidly after peak AST is reached (26). Bilirubin is <34
µmol/L (2 mg/dL) in 80% of cases of toxic or ischemic injury
(26)(27)(42). Lactate
dehydrogenase (EC 1.1.1.27) activity often is higher than that
of AST at presentation in toxic or ischemic hepatic injury
(26)(40)(41), whereas it is
increased on initial determination in only 55% of cases of viral
hepatitis, with average values being only slightly above the upper
reference limit (3). Rarely, cocaine may cause hepatic
injury, usually in patients with coexisting hypotension
(44).
Other causes.
Rarely, Wilson disease and autoimmune
hepatitis (AIH; discussed in more detail in Chronic Hepatic
Injury) can present as acute hepatic injury (Table 2
). Several viruses other than the classical agents [HAV, HBV,
HCV, and hepatitis E virus (HEV)] have been associated with hepatitis,
including herpesvirus, cytomegalovirus (CMV), enterovirus, coronavirus,
reovirus (in neonates), adenovirus, parvovirus B6 (in pediatric
populations), varicella-zoster virus, and Epstein-Barr virus (EBV).
Syphilis, leptospirosis, and toxoplasmosis also may cause hepatic
injury, as may other less common infectious agents. Rarely, other
disorders, including lymphoma, Budd-Chiari syndrome, and venoocclusive
disease, may present with a picture of acute hepatic injury. In
general, hepatic injury associated with these etiologies either is
unusual or is associated with a specific syndrome (chicken pox with
varicella-zoster virus, mononucleosis with EBV, or CMV). Most patients
with other infectious causes of hepatic injury have signs and symptoms
that suggest a particular agent as the cause. Specific diagnosis of
infection by other agents should be pursued when the etiology remains
unknown after more common causes are excluded and when establishment of
a specific diagnosis appears clinically indicated. Superinfection with
other hepatitis viruses may occur in a patient with other forms of
hepatic injury; for example, patients with chronic HCV or alcoholic
hepatitis may become infected with either HAV or HBV and develop an
acute hepatitis as a result of the superimposed infection. In chronic
hepatitis, an acute increase in aminotransferases mimicking acute
hepatic injury can occur with clearance of HBV e antigen (HBeAg)
(45) or with emergence of quasispecies of HCV
(46).
Recommendations:
- In patients with negative viral markers and initial AST >100 times
the upper reference limit, toxic exposure or ischemia should be
suspected (IIB).
- In patients with negative viral markers and enzyme concentrations
8–100 times the upper reference limit, testing must exclude the
possibility of Wilson disease and AIH (IIB).
- Testing for antibody to hepatitis E is not recommended in the United
States unless other viral serologies are negative and there is a
history of recent travel to an endemic area (IIIE).
- Tests for other infectious agents (EBV, CMV, syphilis, toxoplasmosis)
may be used if no other causes are evident (IIB).
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monitoring
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Aminotransferases.
Aminotransferase activities tend to
increase before and peak near onset of jaundice in viral hepatitis,
falling gradually from that point onward (47). Activities
tend to fall slowly in viral hepatitis and alcoholic hepatitis: AST and
ALT decrease, on average, 11.7% and 10.5% per day, respectively, and
remain increased 22 ± 16 and 27 ± 16 days,
respectively (3). In hepatitis A, a secondary increase in
enzymes occurs in 5–10% of cases before activities return to baseline
and is associated with circulating HAV RNA and viral particles in
stool, indicating a potential for transmission of infection
(48)(49)(50). As discussed above, AST and ALT fall rapidly after
reaching peak activities in ischemic and toxic hepatic injury. In all
forms of hepatic injury, decreasing activities occur both with recovery
and with massive necrosis, making enzyme activity a poor indicator of
recovery (20). Once aminotransferases have shown a
consistent pattern of decrease, they need not be checked again until
the patient has clinically recovered. Return of aminotransferases to
normal is not a reliable sign of recovery in hepatitis B or C. In
patients with chronic HCV infection, 49% with normal ALT at the
initial visit after seroconversion developed increased ALT on
subsequent follow-up (51). In hepatitis B, AST and ALT may
return to normal despite persistence of infection
(52)(53).
Bilirubin.
Bilirubin peaks later than aminotransferases, often
by a week or so, and then gradually decreases. Peak bilirubin
>257–342 µmol/L (15–20 mg/dL) is unusual in viral hepatitis. Only
10–12% of patients with viral hepatitis have peak values >257
µmol/L (15 mg/dL), and only 4% have peak values >342 µmol/L (20
mg/dL); higher bilirubin is more common in HBV infection
(3)(13). As total bilirubin declines, the
proportion of 
-bilirubin increases, often reaching 70–80% of total
bilirubin (54)(55). In adults with viral
hepatitis, bilirubin remains increased 30.3 ± 19.7 days after
peak concentrations are reached (3), but it clears more
quickly in children (8); jaundice remains longer than 6
weeks in 34% of adult HBV cases but in only 15% of other forms of
viral hepatitis (8). A prolonged increase in conjugated
bilirubin occasionally occurs with viral hepatitis, particularly with
HAV, but it does not signify a poor prognosis if synthetic function
remains intact (56). Significantly increased bilirubin is
uncommon in toxic and ischemic hepatic injury. Once serum bilirubin has
begun to decrease, there is no reason to measure it again unless
jaundice worsens clinically.
Coagulation tests.
Increased PT is a common finding in
ischemic and toxic hepatic injury, often with results >15 s or 4
s above the reference limit before they rapidly return to normal. There
are no data on the extent to which the increase affects prognosis in
ischemic hepatic injury. An increase in PT to >15 s or >4 s
above reference limits in viral or alcoholic hepatitis is a marker of
more severe disease
(8)(10)(57).
Recommendations:
- PT >4 s above reference limits, bilirubin >257 µmol/L (15
mg/dL), or development of encephalopathy identifies high-risk patients
who require close monitoring and consideration of referral to a
gastroenterologist or hepatologist (IIB).
- In patients with acute hepatitis B, repeat HBsAg measurements should be
performed within 6–12 months; if negative and tests for anti-HBV
surface antigen antibody (anti-HBs) are positive, no additional
follow-up is needed (IIE).
- In patients with acute hepatitis C, ALT should be measured periodically
over the next 1–2 years to assure continued normal results (IIB).
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Chronic Hepatic Injury
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Chronic hepatic injury is a relatively common disorder with
minimal symptoms but long-term risk of significant morbidity and
mortality. It is defined pathologically by ongoing hepatic necrosis and
inflammation of the liver, often accompanied by fibrosis. Chronic
hepatic injury may progress to cirrhosis (15–20% in the case of
chronic HCV) and predisposes to HCC. Most commonly, it is the result of
chronic viral infection. In the United States alone, there are an
estimated 2.1–2.7 million people chronically infected with HCV
(58). There are also 1–1.25 million chronic carriers of
HBV in the United States. Although prevalence rates for HCV infection
generally are between 0.5% and 5% in other parts of the world,
prevalence rates for HBV vary markedly, and in many areas HBV is an
endemic infection. The prevalence of endemic HBV in children is
declining in many parts of the world because of the use of HBV vaccine.
Clinical findings and laboratory investigation often are adequate to
establish the most likely diagnosis, with a predictive value of 88%
for alcoholic hepatitis and 81% for chronic viral hepatitis (before
availability of HCV tests) compared with biopsy (59).
Recommendations:
- In the absence of liver biopsy showing chronic hepatitis, one of the
following clinical definitions should be used to diagnose chronic
hepatitis:
- Persistence of increased ALT for >6 months after an episode of acute
hepatitis; or
- Increased ALT (without another explanation) on more than one occasion
over a period of 6 months. A shorter time may be appropriate in
patients with risk factors for chronic viral hepatitis, genetic causes
of hepatic injury, or autoimmune liver injury, or in the presence of
clinical signs or symptoms of liver disease (IIB).
Although the definition of chronic hepatic injury by increased ALT
is widely accepted, 15–50% of patients with chronic hepatitis C have
persistently normal ALT (51)(60)(61)(62). The
likelihood of continuously normal ALT decreases with increasing number
of measurements; even after three normal ALT values, 11% of patients
with chronic HCV viremia subsequently developed persistently increased
ALT (51). ALT often fluctuates between normal and abnormal,
particularly in chronic hepatitis C; 60% of patients with multiple ALT
measurements have at least occasional normal ALT values (D.R. Dufour,
unpublished observations). The majority of patients with persistently
normal ALT have histologic evidence of chronic hepatitis on biopsy but,
in general, have milder inflammation, less fibrosis, and lower rates of
progression to cirrhosis than do HCV patients with increased ALT
(17)(61). Center for Disease Control and
Prevention guidelines do not recommend treatment of patients with HCV
and persistently normal ALT (63). Although long-term studies
are needed, it appears that the clinical definition proposed will not
miss a significant group of patients who require and benefit from
treatment.
It is not always possible to distinguish acute from chronic hepatic
injury. Most patients with chronic hepatitis C (the most common form of
chronic hepatic injury) have ALT values one to four times the upper
reference limit, and 90% have maximum ALT less than seven times the
upper reference limits, values lower than typically seen in acute
hepatitis. In 5% of cases, however, peak ALT may be >10 times the
upper reference limit, often associated with jaundice, in a pattern
similar to that seen in acute hepatic injury (D.R. Dufour, unpublished
observations). In such cases, it often is necessary to do additional
testing to rule out another cause of acute hepatic injury.
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screening
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General screening of the population for chronic hepatic injury is
not cost-effective and should be limited to high-risk individuals
(64). These include those with a family history of genetic
diseases known to affect the liver, as discussed below, or risk factors
for chronic viral infection (Table 3
). ALT is consistently higher than AST with all causes of
chronic hepatic injury except for alcohol; AST is normal in a
substantial number of cases. ALT may be normal in patients with
cirrhosis, whereas AST remains increased (65)(66)(67)(68). Total and
direct bilirubin and ALP are normal in essentially all patients and are
not useful in screening (59)(69)(70)(71)(72). If
increased ALT is found on routine testing, this should be confirmed by
repeat testing before further evaluation. A minority of individuals
with only one increased ALT value are found to have liver disease
(70)(73). Patients with slightly increased ALT
(one to two times the upper reference limit) are more likely to have a
transient increase not attributable to disease
(59)(71)(73). Approximately 30% of
patients with chronic hepatic injury attributable to HCV have peak ALT
activities less than two times the upper reference limit (D.R. Dufour,
unpublished observations). Because ALT is also found in skeletal
muscle, it is advisable to consider history of exercise and, if
positive, to consider measurement of creatine kinase (EC
2.7.3.2) to rule out skeletal muscle as the origin of ALT
(73)(74).
In patients with risk factors for chronic HBV or HCV infection
(Table 3
), ALT will not identify all infected individuals; HBsAg and
anti-HCV should be measured to screen for chronic infection. Chronic
"carriers" of HBV typically have normal ALT (53), and
15–30% of patients with chronic HCV infection have persistently or
intermittently normal ALT; however, the likelihood of only normal
values decreases with frequency of testing (75). Because
15–25% of individuals with anti-HCV have no detectable viremia,
persons with positive anti-HCV should have qualitative HCV RNA
performed to identify those with persistent infection. HCV RNA may be
transiently present in the early stages of infection. If a patient has
persistently increased ALT and positive anti-HCV, but negative HCV RNA,
the test should be repeated.
Recommendations:
- Screening for chronic hepatitis is recommended in asymptomatic
high-risk individuals (IIB and IIE).
- ALT is the most cost-effective screening test for metabolic or
drug-induced liver injury; AST should also be measured with history of
alcohol abuse (IIB and IIE).
- Specific viral serologies (HBsAg and anti-HCV), as well as ALT, should
be used in individuals at high risk for viral hepatitis (IB).
- Confirmation of chronic HCV infection in an anti-HCV-positive
individual should be made by HCV RNA tests; if negative and ALT is
increased, HCV RNA should be repeated (IIB).
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differential diagnosis
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If the clinical history suggests alcohol abuse and/or AST
activity is greater than ALT (especially if more than twofold higher
than ALT activity), the most likely diagnosis is alcoholic hepatitis.
Virtually no other form of chronic hepatic injury causes AST to be
higher than ALT unless cirrhosis develops (69)(70)(71)(72). Although
the majority of cases of chronic hepatic injury are caused by viruses,
drugs, or ethanol, several other disorders may produce chronic hepatic
injury. Additional tests are not needed if initial evaluation is
consistent with hepatitis B or C or alcoholic hepatitis
(71)(76). Prescription drugs may cause
persistently increased ALT, most commonly with drugs such as
sulfonamides, cholesterol-lowering agents, and isoniazid
(30). In one study from an area with a low prevalence of
viral hepatitis, a history of prescription drug use was common in those
with chronic hepatic injury and no recognizable etiology despite
extensive laboratory testing (77). In patients with
increased ALT, negative viral markers, and a negative history for drug
or alcohol ingestion, the workup should include less common causes of
chronic hepatic injury (Table 4
).
Recommendations:
- Initial evaluation should include a detailed drug history along with
measurement of HBsAg and anti-HCV. If anti-HCV is positive, chronic
infection should be confirmed by qualitative HCV RNA measurement (IIB
and IIE).
- With persistently increased ALT and negative viral markers, the workup
should include anti-nuclear antibodies (ANAs) and iron and iron-binding
capacity (or unsaturated iron-binding capacity; IIIB).
- In patients under age 40, ceruloplasmin should also be measured (IIIB).
- In patients negative for these markers,
1-antitrypsin (A1AT) phenotype may be of use
(IIIB).
- If these tests are negative or inconclusive, diagnostic liver biopsy
should be performed (IIIB).
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workup of patients without obvious cause for chronic hepatic injury
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Nonalcoholic steatohepatitis (NASH).
The occurrence of chronic
liver disease histologically resembling alcoholic hepatitis in patients
without alcohol abuse has been termed NASH. It is the most common cause
of chronic hepatic injury other than viruses and alcohol and the most
common cause of cryptogenic cirrhosis
(59)(69)(70)(78).
Although NASH occurs most commonly in middle-aged women with obesity
and/or diabetes, it also occurs in men and in patients without these
risk factors (78). Patients with NASH commonly have abnormal
lipid profiles, although normal results do not rule out this disease.
It differs from alcoholic hepatitis in that the ALT activity is higher
than AST (except in patients with cirrhosis) (79)(80)(81).
Weight loss may cause significant improvement in enzyme results; in one
study, a 1% reduction in weight produced a 8.1% decrease in ALT
activity (82).
Recommendation:
- Biopsy is necessary to establish the diagnosis of NASH (IIB).
Hemochromatosis.
An autosomal recessive trait, hemochromatosis
is the most common inherited genetic defect in persons of northern
European ancestry (1:200 to 1:300 in the United States)
(83). The vast majority of cases are produced by one of two
point mutations of the HFE gene on chromosome 6. The
majority (60–90%) of affected individuals are homozygous for the
C282Y (845A) mutation, whereas a minority has compound heterozygosity
for this mutation and the H63D (187G) mutation
(84)(85). Screening involves detection of
increased transferrin saturation (saturation = serum iron
x 100/total iron-binding capacity) (86) or low
unsaturated iron-binding capacity (87). A transferrin
saturation cutoff of 
45% or unsaturated iron-binding capacity cutoff
28 µmol/L (155 µg/dL) has a sensitivity of 90–100% for
homozygosity for the C282Y mutation; if fasting specimens are used, the
specificity is 43% (88)(89). A recent consensus
conference recommended that definitive diagnosis be made by genetic
analysis (90). Although several recent publications have
shown the feasibility of hemochromatosis screening using transferrin
saturation, most organizations and researchers do not currently
recommend screening because of unresolved issues regarding their
ability to convince young adults to be tested, the specificity and
reproducibility of screening tests, and questions about natural history
of untreated disease (90)(91)(92). Screening has been advocated
by the College of American Pathologists (93), and has been
estimated to save $3.19 per blood donor screened (94).
Recommendations:
- Initial evaluation for hemochromatosis should be by fasting serum
transferrin saturation or unsaturated iron-binding capacity (IIB).
- Transferrin saturation 45% or unsaturated iron-binding capacity 28
µmol/L (155 µg/dL) should be followed by analysis for
HFE gene mutations (IIB).
- Screening of the population may be beneficial but is not currently
recommended pending clarification of screening benefits (IIB and IIE).
Wilson disease.
An autosomal recessive disorder, Wilson
disease occurs in 1 in 30 000 individuals in Europe and North
America. It is caused by a mutation of a gene on chromosome 13 coding
for an ATPase needed for copper transport (95). Wilson
disease may present as liver disease, neurologic problems, or with
psychiatric symptoms, almost always before age 40. Most patients who
present with liver disease do not have neurologic manifestations
(96). The most common diagnostic finding is low plasma
ceruloplasmin. Low concentrations also occur with malnutrition, protein
loss, and advanced liver disease, and falsely normal values can occur
with pregnancy, estrogen administration, and acute inflammation
(97). Most references report low ceruloplasmin in 95% of
homozygotes and 20% of heterozygotes (97)(98)(99). One study
found normal ceruloplasmin in 35% of patients with chronic liver
disease attributable to Wilson disease (confirmed by genetic studies in
80%) but in only 15% of patients with Wilson disease without overt
liver involvement (96). Other expected findings in Wilson
disease include increased serum free copper, decreased total serum
copper, increased urine copper excretion, and increased liver copper
content. These tests may also provide misleading results in patients
with Wilson disease (96)(100). Multiple tests
frequently are needed to establish the diagnosis.
Recommendations:
- Testing for Wilson disease with ceruloplasmin is indicated in
patients under age 40 with chronic hepatic injury or fatty liver and
negative workup for viral hepatitis, drug-induced liver injury, and
hemochromatosis (IIB).
- Screening for Wilson disease in all patients with chronic hepatic
injury is not indicated (IIB and IIE).
- Genetic marker testing may be useful in equivocal cases, but testing
must be able to detect multiple mutations in the Wilson disease gene
(IIIB).
AIH.
AIH is responsible for up to 18% of chronic hepatitis
not attributable to viruses or alcohol (101). Several
variants of AIH have been described (102). Type 1, found
primarily in young and middle-aged women, is the most common form; it
is associated with high titers of ANA and/or anti-smooth muscle
antibody (ASMA). Type 2, found primarily in children, is common in
western Europe but rare in the United States; it is associated with
antibodies to liver-kidney microsomal antigen, but rarely with
positive ANA or ASMA. Many patients with type 2 also have HCV
infection. Type 3, found primarily in young women, is associated with
systemic autoimmune disease in many cases. Most affected individuals
lack ANA, ASMA, or anti-liver-kidney microsomal antibodies, but are
positive for antibodies for soluble liver antigen. Standardized
diagnostic criteria and a scoring system have been defined by an
international panel (103). The classic features of the most
common type 1 include increased aminotransferases; minimal or no
increases in ALP; polyclonal hypergammaglobulinemia (at least 1.5 times
the upper reference limit); no evidence of viral infection, risk
factors for viral infection, or exposure to drugs or alcohol; and
positive ANA or ASMA (at least 1:80) (103). Approximately
40% of patients with chronic HCV infection have a positive ANA or
ASMA, usually in low titers (102). False-positive anti-HCV
results have been reported in 60% of patients with AIH when
second-generation tests are used, and in 20% when third-generation
assays are used (104); anti-HCV typically disappears with
successful treatment (105). In equivocal cases, HCV RNA (or
a recombinant immunoblot assay) can be used to establish the diagnosis
(104).
Recommendations:
- AIH should be suspected in patients with chronic hepatic injury and
increased immunoglobulins and absence of viral markers or risk factors
for viral hepatitis (IIIB).
- The diagnosis of type 1 AIH can be clinically supported by positivity
for either ANA or ASMA in high titers (IIIB).
Primary biliary cirrhosis and primary sclerosing cholangitis.
Primary biliary cirrhosis (PBC) and primary sclerosing cholangitis
(PSC) are autoimmune diseases that cause destruction of bile ducts.
Although PBC and PSC characteristically cause increases in ALP and
-glutamyltransferase (EC 2.3.2.2), patients with these
diseases may have increased AST and ALT and be considered to have
chronic hepatitis. PBC is associated with destruction of intrahepatic
bile ducts; it is often associated with other autoimmune disorders,
particularly Sjogren syndrome (up to 80% of cases) (106).
An autoimmune marker, anti-mitochondrial antibody (AMA), is found in
almost all patients with PBC; although other diseases may be associated
with positive AMA, in PBC the antibody is directed against the pyruvate
dehydrogenase complex (so-called M2 type of AMA), particularly to
dihydrolipoamide acetyltransferase (E2) and E3-binding protein
(107). Approximately 5–10% of patients have features of
both PBC and AIH (108)(109). PBC often is
detected in asymptomatic individuals by a finding of increased ALP. AST
and ALT are increased in approximately one-half of cases,
although values are more than two times the reference limit in
20% (110). PSC is associated with damage to both intra- and
extrahepatic bile ducts; 70% of cases are associated with inflammatory
bowel disease (Crohn disease or ulcerative colitis) (111).
Perinuclear anti-neutrophil cytoplasmic antibodies are found in
approximately two-thirds of all cases (112). In PSC,
antibodies commonly are directed against
bactericidal/permeability-increasing protein, cathepsin G, and/or
lactoferrin. There appears to be no prognostic significance to the
different antibody specificities, although patients with cirrhosis more
commonly have antibody to multiple antigens and to antigens other than
lactoferrin (113). ASMA and ANA are also present in up to
70% of cases (114).
Recommendations:
- PBC or PSC should be suspected in patients with chronic cholestasis
(IIIB).
- The diagnosis can be clinically supported by positivity for AMA (PBC)
or anti-neutrophil cytoplasmic antibodies (PSC) in high titers (IIIB).
A1AT deficiency.
A1AT is the most important protease
inhibitor; congenital deficiency occurs in 1 in 1000 to 1 in 2000
persons of European ancestry. The gene for A1AT is located on
chromosome 14 (115); deficiency is usually attributable to a
single amino acid substitution that alters carbohydrate binding and
impairs release from hepatocytes (116). The most important
deficiency involves homozygosity for the Z variant, termed Pi (for
protease inhibitor) ZZ. Deficiency is associated with emphysema and
neonatal hepatitis (117); chronic hepatic injury with
cirrhosis and HCC (118) have also been reported. Almost all
Pi ZZ neonates have evidence of liver injury at birth; this usually
resolves by age 12 years (117). In adults, 50% of Pi
Z-positive individuals (either homozygotes or heterozygotes) develop
cirrhosis, and 31% develop HCC (116). There is also an
excess of Pi Z heterozygotes among patients referred for liver
transplants, particularly among patients with cryptogenic cirrhosis,
where 25% of patients are Pi Z positive (119). There is
evidence, however, that A1AT deficiency or heterozygosity for Pi Z
phenotype may not directly cause liver disease, but increase
susceptibility to liver damage by other agents, especially viruses. Two
controlled studies found the same frequency of Pi Z (either homozygous
or heterozygous) in patients with liver disease and controls
(120)(121). In a study of 164 patients with Pi
Z, 40% had chronic liver disease; 87% were also positive for HCV
antibodies or HBV markers, and only 11% had no other liver disease
risk factors (122). Because A1AT is an acute phase reactant,
quantitative concentrations may be falsely normal with infection or
inflammation, and falsely low concentrations may occur with
malnutrition, protein-losing states, or end stage liver disease. In one
study, quantitative concentrations were normal in 42% of heterozygous
Pi Z patients with liver disease (123). Testing for A1AT
deficiency should use phenotype analysis rather than quantitative
plasma concentration (116).
Recommendations:
- Testing for A1AT deficiency may be of benefit in patients with
chronic hepatic injury and no other apparent cause, although the role
of A1AT deficiency in liver disease in adults is not clearly defined
(IIB).
- Testing is especially important in neonates with evidence of hepatic
injury (IIB).
- Testing for A1AT variants should be performed by determination of
phenotype (IIB).
- Screening patients with chronic hepatic injury for A1AT deficiency is
not recommended (IIIB and IIIE).
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other viruses
|
|---|
Two other viruses have been suggested as possibly involved in the
pathogenesis of chronic hepatitis: hepatitis G (HGV) and TT virus
(TTV). Both viruses can be transmitted by transfusion, and chronic
viremia is present with both. To date, evidence has suggested that
infection with these viruses is common, but there is no clear
indication that they play a role in liver injury. HGV (and the related
GB virus type C) are members of the flavivirus family, as is
HCV. HGV was first isolated from patients following transfusion,
although most showed no evidence of liver injury
(124)(125). HGV can also frequently be found in
chronic hepatitis (126), but it does not appear to be a
common cause of cryptogenic chronic liver disease (127).
This may be because HGV RNA is rarely found in the liver in chronically
viremic patients (128). TTV was first identified in patients
with posttransfusion hepatitis (129). TTV DNA is found in
1–7% of blood donors in the United States
(130)(131). The presence of TTV DNA is no more
common in persons with acute non-A-E hepatitis than in other causes of
acute hepatitis or in control patients
(131)(132).
Recommendation:
- Testing for HGV or TTV, in other than a research setting, is not
recommended (IIIE).
|
monitoring
|
|---|
Although ALT is the most clinically used laboratory test for
monitoring liver injury, there often are considerable fluctuations in
enzyme activities over time (particularly in chronic HCV infection)
(60)(61). It is important to measure ALT
repeatedly in chronic HCV before concluding that ALT is normal
(75); 43% of chronically infected individuals have ALT
values fluctuating between normal and abnormal, and 16% of those with
normal ALT on their first two visits and 11% of those with normal ALT
on their first three visits subsequently develop increased ALT
(51). In patients with chronic HBV infection without
increased ALT (chronic carriers), 10% will develop increased
ALT on follow-up (53); ALT should therefore be measured
periodically even if initially normal.
With both chronic HBV and HCV, clearance of viral markers is the most
reliable method for detecting resolution of infection. In untreated
hepatitis B, a small percentage of patients spontaneously clear viral
antigens; in long-term studies, loss of HBeAg occurred in one-third to
one-half of patients (45)(133)(134).
In those that lose HBeAg, 5–10% will subsequently clear HBsAg over 10
years of follow-up (53)(135). HBeAg should be
rechecked periodically if initially positive. If HBeAg is negative and
anti-HBV e antigen antibody (anti-HBe) is positive, this may
indicate either the beginning of viral clearance from the body or
integration of HBV DNA into host DNA and loss of ability to form
replicating virus. HBsAg and anti-HBs should be measured periodically
to look for viral clearance because HBsAg will remain positive in those
with integration of HBV DNA. In treatment of HBV, the likelihood of
viral clearance is related to baseline ALT activity; patients with
increased ALT are more likely to respond than those with initially
normal ALT activity (136)(137). Successful
treatment is associated with loss of HBV DNA, HBsAg, and HBeAg.
Although there is evidence that quantitative HBeAg correlates well with
HBV DNA (138)(139)(140), quantitative HBeAg assays are not
commercially available. HBeAg may disappear even in patients who show
no response to therapy (141). Moreover, there is an
increasing frequency of "pre-core" mutants that cannot produce
HBeAg, particularly in endemic areas in Asia and the Mediterranean
region (142). Patients infected with such mutants have
anti-HBe but continue to have circulating HBV DNA. In infection with
normal strains, HBV DNA remains detectable longer than does HBsAg in
recovery (143). When viral DNA integrates into the host
genome, HBsAg is still produced, although HBeAg and HBV DNA commonly
are negative in plasma (144)(145). With
lamivudine treatment, however, production of viral nucleic acid through
reverse transcriptase is inhibited (145), although viral DNA
concentrations in the hepatocytes are not changed (137). For
these reasons, use of HBV DNA, HBeAg, and HBsAg may all be useful in
monitoring patients with chronic HBV because no single test provides
unequivocal evidence of viral clearance.
Most studies have shown that HCV RNA fluctuates over time but rarely
varies by more than 1 log; in most cases, variation is <0.5 log
(146)(147)(148). In patients tested repeatedly over several
years, HCV RNA increases by an average of 0.25 log/year over time
without treatment (149). In some series, however, up to a
3-log difference is seen in patients with increased ALT when HCV RNA is
measured monthly (150); in approximately one-third of
chronically infected patients, HCV RNA can fluctuate between a mean of
106 copies/mL and undetectable (151).
Currently, antiviral treatment is recommended for patients with chronic
HCV infection who have increased ALT and more than mild inflammatory
changes on biopsy. The most effective therapy currently available is
combined ribavirin and interferon. Laboratory tests have been found
helpful in predicting response to varying lengths of therapy and in
detecting those who are not responding to treatment and in whom therapy
should probably be discontinued. In those treated with combination
therapy, both viral load and genotype have been found to identify
patients who may respond to 24 rather than 48 weeks of therapy
(152)(153).
In a combined analysis of these two studies, five factors were found
useful in predicting response (Table 5
). Persons with genotype 2 or 3, along with three or four other
favorable risk factors, can be treated effectively with only 24 weeks
of therapy; all other patients do better with 48 weeks of therapy
(154). The best indicator of viral clearance is persistent
absence of HCV RNA (determined by qualitative HCV RNA assays). The
absence of HCV RNA 6 months after completion of treatment is associated
with a <10% likelihood of recurrent HCV viremia (155). A
decrease in viral load in the absence of clearance is not reliable
evidence of treatment success; however, failure of HCV RNA to decline
to <400 000 copies/mL by 12 weeks of therapy is associated with 100%
likelihood of persistent HCV RNA at the end of treatment
(154). An approach to monitoring treatment of patients with
HCV by combination therapy is outlined in Fig. 2
. Some patients cannot take ribavirin; the only current
treatment option for such patients is interferon monotherapy. With this
form of treatment, failure of HCV RNA to fall to undetectable
concentrations or failure of ALT to return to normal at 12 weeks after
initiation of therapy is associated with a >95% likelihood of
treatment failure, and is considered a reason to discontinue therapy
(156).
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Figure 2. Management of therapy in chronic hepatitis C: laboratory
testing depends on type of treatment given.
At present, combined ribavirin-interferon is recommended for all
patients without contraindications. HCV RNA should be measured at 24
weeks of treatment; if positive, treatment should be discontinued. If
negative, duration of treatment is based on number of favorable risk
factors present (see Table 5
). If four or more factors are favorable
(and genotype is 2 or 3), treatment is stopped; in other cases,
treatment is continued for 48 weeks. If -70 °C storage is
available, specimens for HCV genotype and viral load can be obtained
before treatment and frozen until after the 24-week testing is
performed; if not, testing should be performed before therapy. In those
patients who cannot tolerate ribavirin, monotherapy with interferon is
used. ALT and qualitative HCV RNA should be checked after 12 weeks of
therapy; if ALT remains increased or HCV RNA is detectable, treatment
should be discontinued. There is no benefit to determination of
quantitative HCV RNA or genotype when interferon monotherapy is used.
|
|
The optimal frequency of laboratory tests in patients with chronic
hepatitis C has not been determined. The European Association for the
Study of the Liver Consensus Conference on Hepatitis C recommends that
complete blood counts and liver enzymes be performed every 6 months in
untreated patients (157). The major complications of
treatment with interferon are depression, thrombocytopenia, and
hypothyroidism, whereas hemolytic anemia is the major complication of
ribavirin therapy. The European Association for the Study of the Liver
recommends complete blood counts weekly during the first 4 weeks of
treatment and regular determinations after the first 4 weeks. They also
recommend measurement of thyroid-stimulating hormone every 6
months during therapy.
Recommendations:
- In viral hepatitis, viral markers are the most reliable markers of
resolution of hepatitis (IIB).
- HCV RNA quantification and genotype are important determinants of
duration of combination therapy. To reduce the expense of testing, if
feasible, specimens should be obtained before treatment and stored at
-70 °C pending results of treatment. If this is not possible,
testing should be performed before treatment is begun (IIB and IIE).
- In patients with HCV treated with interferon and ribavirin, qualitative
HCV RNA should be measured after 24 weeks of treatment to determine
potential responders. If genotype and quantitative HCV RNA were not
performed but specimens were frozen for their analysis before
treat
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Abstract
Introduction
