Evaluation of SICKLEQUIK, a differential solubility test for hemoglobin S

Researchers evaluated a differential tube solubility test's ability to detect Hemoglobin S (Hb S) in sickle cell conditions. Six hundred twenty-nine blood samples, including 190 S hemoglobinopathies, were used to assess test performance. Alkaline cellulose acetate electrophoresis was used to confirm all results. The test correctly indicated the presence of Hb S in every case in which Hb S was found on electrophoresis. Six of the 198 specimens containing Hb S incorrectly differentiated the heterozygous from the homozygous state (two with Hb AS, three with Hb SF, and one with Hb SC). Electrophoresis later showed four of these samples to be inappropriate for solubility testing. Three of these specimens contained Hb SF and the other specimen contained Hb SC. One specimen from a patient with polycythemia gave a false positive result. Results were compared using different methods of centrifugation. This solubility test was found to be dependable as a screening method provided the manufacturer's directions are followed and all positive results are confirmed by electrophoresis.