Laboratory investigation of
hemoglobinopathies includes complete blood count (CBC),
hemoglobin (Hb) typing by high performance liquid chromatography (HPLC) and
DNA analysis.
DNA analysis is the most reliable method but requires a manually laborious procedure and is time consuming. A more practical method of detecting abnormal Hbs is the HPLC technique, because it is more rapid and easier to interpret.
Hb Constant Spring (
Hb CS; HBA2: c.427T > C) is an abnormal variant that is labile and difficult to detect using conventional methods. To evaluate the efficiency of
Hb CS determination by HPLC, blood samples from 578 subjects were analyzed using an automated cell analyzer for hematological parameters, automated HPLC for Hb identification, and polymerase chain reaction (PCR) for α-
thalassemia (α-thal) and
Hb CS confirmation. These included 169 normal, 119 heterozygous α-thal-2, 30 homozygous α-thal-2, 177 heterozygous α-thal-1, 59 heterozygous
Hb CS, seven homozygous
Hb CS and 17 compound heterozygous α-thal-2 and
Hb CS subjects. The results showed that sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of
Hb CS by HPLC were 93.78, 99.80, 98.73 and 99.00%, respectively. The mean of misdiagnosis value of the three groups of
Hb CS subjects (total 83) was 6.02% (n = 5), with percentages for heterozygous
Hb CS, homozygous
Hb CS, and compound heterozygous α-thal-2 and
Hb CS being 6.8, 0.0 and 5.9%, respectively. The HPLC method yielded good results, although it may also lead to misdiagnosis of
Hb CS due to the relatively small amount and lability.