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Clinical Chemistry 48: 391-a, 2002;
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(Clinical Chemistry. 2002;48:391.)
© 2002 American Association for Clinical Chemistry, Inc.

Letters

Screening for Hemoglobin Variants with Abnormal Oxygen Affinity

Robert W. Burnett1a

1 Department of Pathology and Laboratory Medicine, Hartford Hospital, Hartford, CT 06102

aE-mail rburnet{at}harthosp.org


To the Editor:

Rai et al. (1) recently described an elegant method for detecting hemoglobin (Hb) variants that cause erythrocytosis, using electrospray mass spectrometry. Many of these variants are not detectable with conventional electrophoretic techniques. The authors also stated that "functional studies of oxygen saturation curves would be the ideal method to screen for Hb variants that cause erythrocytosis, but such methods are not generally available.... "

On the contrary, the determination of P50 (partial pressure of O2 at which Hb is half-saturated) is easily done in any laboratory with a blood gas analyzer and a multiwavelength oximeter. The P50, when normalized to pH 7.40 and a PCO2 of 5.33 kPa (40 mmHg), is a direct (inverse) reflection of Hb oxygen affinity. A one-point method and calculation have been described in an IFCC Guideline (2), and these or equivalent calculations have been included in the software of many blood gas analyzers and can be performed automatically. Heparinized venous blood is used.

One advantage of electrospray mass spectrometry is that specimens do not need to be analyzed immediately, but can be stored and shipped to a laboratory where the electrospray mass spectrometry method is available. On the other hand, heparinized whole blood specimens for P50 determination are stable for at least 2–3 h at room temperature, and minimal change is observed after 24 h when specimens are held at 4 °C (3).

We have routinely used P50 measurements with instruments in the laboratory for many years to screen for Hb variants in patients with unexplained anemia or erythrocytosis.


References

  1. Rai DK, Griffiths WJ, Alvelius G, Landin B. Electrospray mass spectrometry: an efficient method to detect silent hemoglobin variants causing erythrocytosis. Clin Chem 2001;47:1308-1311.[Free Full Text]
  2. Wimberely PD, Burnett RW, Covington AK, Fogh-Andersen N, Maas AHJ, Müller-Plathe O, et al. Guidelines for routine measurement of blood hemoglobin oxygen affinity. Scand J Clin Lab Invest 1990;50(Suppl 203):227-234.
  3. Kwant G, Oeseburg B, Zijlstra WG. Reliability of the determination of whole-blood oxygen affinity by means of blood-gas analyzers and multi-wavelength oximeters. Clin Chem 1989;35:773-777.[Abstract/Free Full Text]




This Article
Right arrow Extract Freely available
Right arrow Full Text (PDF)
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the Editor about this paper
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Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
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Citing Articles
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Google Scholar
Right arrow Articles by Burnett, R. W.
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PubMed
Right arrow Articles by Burnett, R. W.
Related Collections
Right arrow General Clinical Chemistry

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