Cryohemolysis test as a diagnostic tool for hereditary spherocytosis.

The cryohemolysis test has been proposed as a new method of identifying hereditary spherocytosis. The purpose of the present study was to analyze the sensitivity and specificity of this method in comparison to the measurement of osmotic fragility. The examination included 61 patients suffering from hereditary spherocytosis and 58 patients with other hemolytic and nonhemolytic anemias. Hereditary spherocytosis patients showed significantly higher cryohemolysis values (median 29.7%, range 12.3-50.2%) than both normal subjects (median 3%, range 0.5-27%) and all other anemic patients excepting those with immune hemolytic anemia (median 4%, range 0.5-10.1%). Analysis of immune hemolytic anemia revealed broadly scattered values ranging from 1.4% to 53.5% (median 8.6%). Taking 15% as the threshold value, the sensitivity and specificity of the cryohemolysis test for hereditary spherocytosis were 95% and 96%, respectively. It is concluded that the simple-to-perform cryohemolysis test is quite comparable to the estimation of red cell osmotic fragility and therefore very useful as a diagnostic measure of hereditary spherocytosis.