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Articles |
Departments of
1
Biochemistry,
2
Endocrinology, and
3
Internal Medicine, Hospital de Galdakao, 48960 Vizcaya, Spain.
a Address correspondence to this author at: Laboratorio de Bioquímica, Hospital de Galdakao, Barrio Labeaga s/n. Galdakao, 48960 Vizcaya, Spain. Fax 34-94-4007128; e-mail mesteban{at}hgda.osakidetza.net
Background: LDL-cholesterol (LDL-C) concentrations are the primary basis for treatment guidelines established for hyperlipidemic patients. LDL-C concentrations are commonly monitored by means of the Friedewald formula, which provides a relative estimation of LDL-C concentration when the triglyceride concentration is <2000 mg/L and there are no abnormal lipids. The Friedewald formula has several limitations and may not meet the current total error requirement of <12% in LDL-C measurements.
Methods: We evaluated the analytical and clinical performance of two direct methods (Roche and Wako) by analyzing 313 fresh serum samples obtained from dyslipidemic patients in a lipid clinic and comparing them with modified ß-quantification.
Results: Both homogeneous assays displayed excellent precision (CV <2%). The Roche method showed a mean total error of 7.72%, and the Wako method showed a mean total error of 4.46% over a wide range of LDL-C concentrations. The Roche method correlated highly with the modified ß-quantification assay (r = 0.929; y = 1.052x - 168 mg/L; n = 166) and showed a bias of -4.5% as a result of the assigned standard value. The Wako method also correlated highly with ß-quantification (r = 0.966; y = 0.9125x + 104.8 mg/L; n = 145) without significant bias. The Roche method correctly classified 97% of patients with triglycerides <2000 mg/L, 75% of patients with type IIb hyperlipemia (HPL), and 84% of patients with type IV HPL based on the cutpoints of 1300 and 1600 mg/L, compared with 98%, 78.4%, and 89%, respectively, for the Wako method. In dysbetalipoproteinemic patients, both methods have a 30% mean positive bias compared with ß-quantification.
Conclusions: Both direct methods can be a useful alternative when ultracentrifugation is not available for the diagnosis and control of lipid-lowering medication for patients with mixed HPL, but not for patients with type III hyperlipidemia.
The following articles in journals at HighWire Press have cited this article:
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  D. J. Blom, F. H. O'Neill, and A. D. Marais Screening for Dysbetalipoproteinemia by Plasma Cholesterol and Apolipoprotein B Concentrations Clin. Chem., May 1, 2005; 51(5): 904 - 907. [Full Text] [PDF]
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 E. T. Bairaktari, K. I. Seferiadis, and M. S. Elisaf Evaluation of Methods for the Measurement of Low-Density Lipoprotein Cholesterol Journal of Cardiovascular Pharmacology and Therapeutics, January 1, 2005; 10(1): 45 - 54. [Abstract] [PDF]
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S. Usui, H. Kakuuchi, M. Okamoto, Y. Mizukami, and M. Okazaki Differential Reactivity of Two Homogeneous LDL-Cholesterol Methods to LDL and VLDL Subfractions, as Demonstrated by Ultracentrifugation and HPLC Clin. Chem., November 1, 2002; 48(11): 1946 - 1954. [Abstract] [Full Text] [PDF]
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G. R. Warnick, W. G. Miller, P. P. Waymack, and F. P. Anderson Lack of Agreement of Homogeneous Assays with the Reference Method for LDL-Cholesterol May Not Indicate Unreliable Prediction of Risk for Cardiovascular Disease * Authors of the article cited above respond: Clin. Chem., October 1, 2002; 48(10): 1812 - 1815. [Full Text] [PDF]
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W. G. Miller, P. P. Waymack, F. P. Anderson, S. F. Ethridge, and E. C. Jayne Performance of Four Homogeneous Direct Methods for LDL-Cholesterol Clin. Chem., March 1, 2002; 48(3): 489 - 498. [Abstract] [Full Text] [PDF]
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M. Nauck, G. R. Warnick, and N. Rifai Methods for Measurement of LDL-Cholesterol: A Critical Assessment of Direct Measurement by Homogeneous Assays versus Calculation Clin. Chem., February 1, 2002; 48(2): 236 - 254. [Abstract] [Full Text] [PDF]
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J. Ordonez-Llanos, A. M. Wagner, R. Bonet-Marques, J. L. Sanchez-Quesada, F. Blanco-Vaca, and F. Gonzalez-Sastre Which Cholesterol Are We Measuring with the Roche Direct, Homogeneous LDL-C Plus Assay? Clin. Chem., January 1, 2001; 47(1): 124 - 126. [Full Text] [PDF]
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