Hereditary spherocytosis in neonates with hyperbilirubinemia.

OBJECTIVES: Hereditary spherocytosis (HS) is the most common inherited hemolytic disease among people of Northern European decent. Neonates with HS can develop significant hyperbilirubinemia, but we suspect that HS is underrecognized as a cause of neonatal jaundice.
METHODS: We used electronic record repositories of Intermountain Healthcare to identify all neonates with a diagnosis of HS in a recent 5-year period. We compared these with the number of new HS cases anticipated on the basis of national prevalence and also with the number who had elevations in mean corpuscular hemoglobin concentration (MCHC), red cell distribution width (RDW), and bilirubin. We compared MCHC and RDW values of neonates who had direct antiglobulin test-positive (DAT[+]) and DAT(-) results and jaundice with values of neonates who had HS.
RESULTS: Eight neonates received a diagnosis of HS; however, we may have failed to diagnose 90% of cases. To assess whether some with a missed diagnosis of HS developed significant hyperbilirubinemia, we examined records of all 670 with a bilirubin level of >or=20 mg/dL. Records of the 20 with the highest MCHC and RDW values suggested that HS was present but unrecognized in at least 7. Follow-up revealed a subsequent diagnosis of HS in 5; the other 2 are no longer in our health system. MCHC and RDW values were highest in those with HS, intermediate in the DAT(+) group, and lowest in the DAT(-) group. An MCHC of >or=36.0 g/dL had 82% sensitivity and 98% specificity for identifying HS.
CONCLUSION: We speculate that HS is underrecognized as a cause of neonatal hyperbilirubinemia. We speculate further that an MCHC of >or=36.0 g/dL can alert caregivers to the possibility of HS.