Evaluation of Cation-Exchange HPLC Compared with Isoelectric Focusing for Neonatal Hemoglobinopathy Screening

Background: Central Middlesex Hospital, in northwest London, has screened neonates for hemoglobinopathies, using the established manual technique of isoelectric focusing (IEF) since 1989. Recently, this laboratory has faced a large increase in the number of samples tested per year. This study compared the detection of hemoglobin abnormalities between the existing manual IEF method and that of automated cation-exchange HPLC to determine the reliability of HPLC and whether an automated system would save time in the laboratory.Methods: Over a 15-month period, 25 750 blood samples, collected by heel prick onto filter paper, were tested using HPLC, and the results were compared with those obtained with IEF.Results: HPLC and IEF each identified 568 patients with FAS, 151 with FAC, 49 with FAD-Punjab, 23 with FS, 3 with FC, 6 with FSC, 5 with FE, and 1 with FD. IEF detected 62 patients with FAE, whereas HPLC detected 63. This additional FAE was observed on repeat IEF. One additional heterozygote detected by HPLC was initially not observed by IEF, but was detected on repeat IEF. HPLC detected all but six cases of Hb Barts observed by IEF. One double heterozygote and four heterozygotes were detected by IEF, but not by HPLC. The detection of hemoglobin variants expressed at low concentrations was comparable for the two methods, and carryover was not observed in routine analysis on HPLC.Conclusions: HPLC is a sensitive, efficient, and time-saving alternative to IEF for the neonatal screening of common hemoglobinopathies.