Detection of Mutant Hemoglobins with Altered Affinity for Oxygen

The detection of high- or low-affinity hemoglobins in subjects with polycythemia or anemia is difficult for most physicians because of the requirement for special equipment to do oxygen-hemoglobin dissociation curves. Measurement of the pH, oxygen tension, and oxygen saturation of antecubital venous blood with instruments present in most clinical chemistry laboratories permits an estimate of the strength of oxygen binding to hemoglobin. An equation can be used to convert the venous oxygen tension (standardized to pH 7.4) and the oxygen saturation to the P50 of the oxygen-hemoglobin dissociation curve on which the observed point falls. The data indicate that this method is a reliable initial step in the identification of a hemoglobin with abnormal affinity for oxygen and may be applied to population studies, since reliable results are obtained with venous blood stored at 4 degrees C for up to 24 hours.