Evaluation of cation-exchange HPLC compared with isoelectric focusing for neonatal hemoglobinopathy screening

Background: Central Middlesex Hospital, in northwest London, has screened n eonates for hemoglobinopathies, using the established manual technique of i soelectric focusing (IEF) since 1989. Recently, this laboratory has faced a large increase in the number of samples tested per year. This study compar ed the detection of hemoglobin abnormalities between the existing manual IE F method and that of automated cation-exchange HPLC to determine the reliab ility of HPLC and whether an automated system would save time in the labora tory. Methods: Over a 15-month period, 25 750 blood samples, collected by heel pr ick onto filter paper, were tested using HPLC, and the results were compare d 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 wit h FD. IEF detected 62 patients with FAE, whereas HPLC detected 63. This add itional FAE was observed on repeat IEF. One additional heterozygote detecte d 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 h eterozygote and four heterozygotes were detected by IEF, but not by HPLC. T he detection of hemoglobin variants ex-pressed at low concentrations was co mparable for the two methods, and carryover was not observed in routine ana lysis on HPLC. Conclusions: HPLC is a sensitive, efficient, and timesaving alternative to IEF for the neonatal screening of common hemoglobinopathies. (C) 1999 Ameri can Association for Clinical Chemistry.