Neonates with Down's Syndrome (DS) frequently develop hyperbilirubinemia(peak serum total bilirubin (Bili) ≥15mg/dL). The aim of the study was to determine whether jaundice in DS neonates is due to increased bilirubin production, resulting from rapid heme degradation, reflected by carboxyhemoglobin (COHb) values. Blood for COHb and Bili was sampled from DS neonates and controls on the 3rd day of life. COHb was measured by gas chromatography and expressed as% total hemoglobin (tHb). Inspired air CO concentrations were determined by electrochemistry, and measured COHb corrected for inspired CO (COHbc). Peak Bili (possibly modified by phototherapy) was recorded. Mean ± SD were calculated and compared using Student's t test. Significance is defined as p<0.05.Table

Table 1
Full size table

We conclude that heme degradation was significantly increased in the DS neonates. Despite this increased bilirubin production, 3rd day and peak Bili values were similar. This implies factors additional to increased bilirubin production in the pathogenesis of the jaundice, possibly diminished bilirubin elimination. Neonates with DS may have an inherent defect of their erythrocytes, predisposing them to abnormal erythropoiesis or rapid hemolysis.