Extreme hyperbilirubinemia in newborn infants.

This study was undertaken to determine the frequency and investigate the etiology of extreme hyperbilirubinemia (total serum bilirubin [TSB]>or=25 mg/dL [428 micromol/L]) in newborns admitted to a neonatal intensive care unit in southern Turkey. The charts of 93 term and near-term infants admitted with TSB levels of 25 mg/dL (428 micromol/L) or greater in the first 30 days after birth were retrospectively reviewed. During the 4.5-year study period, 774 infants were admitted to our unit with neonatal jaundice. Ninety-three (12%) of these infants had TSB levels of 25 mg/dL (428 micromol/L) or greater. The mean TSB level in the 93 cases was 30.1+/-5.7 mg/dL (514.7+/-97.5 micromol/L), and the peak levels ranged from 25.0 to 57.4 mg/dL (428-981.5 micromol/L). Thirty-three (35.5%) of the 93 babies had TSB levels of 30 mg/dL (513 micromol/L) or greater. Eighty-nine of 93 infants were being exclusively breast-fed. Nineteen babies were isoimmunized, 7 were bacteremic, 2 of the 39 babies tested for glucose-6-phosphate dehydrogenase had this enzyme deficiency, and 1 of the 71 infants tested for thyroid function had hypothyroidism. No cause for extreme hyperbilirubinemia was found in 61 (65.6%) cases.