Diagnosis of hereditary spherocytosis in newborn infants.

The normal range of red blood cell osmotic fragility and autohemolysis was determined in venous blood of 32 healthy newborn infants. With these normal ranges as a reference, the diagnosis of hereditary spherocytosis was definitely possible in five newborn infants by demonstration of increased osmotic fragility of fresh and incubated red blood cells, moderately increased autohemolysis, and partial reduction of autohemolysis by the addition of glucose. Most previously studied newborn infants with hereditary spherocytosis have had atypical hyperbilirubinemia. Inconstant signs are anemia, reticulocytosis, erythroblastosis, spherocytes in the blood smear, and increased mean corpuscular hemoglobin concentration. In newborn infants with atypical hyperbilirubinemia in whom blood group incompatibilities are excluded, studies for hereditary spherocytosis should be done.