Hemolytic pattern of erythrocytes in the newborn measured by the coil planet centrifuge system and its relationship to neonatal jaundice.

Dynamic osmotic fragility of erythrocytes in cord blood and its changes during the neonatal period were studied by means of a coil planet centrifuge system. The starting-point for hemolysis in the newborn become similar to that of adult blood after approximately a week, while the shift of the end-point to the adult range required one month or more. The percentage of fragile cord blood cells with a hemolysis starting-point above 110 m osmol and the maximum bilirubin level during neonatal period were examined. A high percentage of fragile cells was associated with high bilirubin levels, and when fragile cells comprised more than 7.0% of the total cord blood erythrocytes, the bilirubin level tended to rise above 15 mg/dl.