Abstract â–¡ 119

Background: The study investigated the urinary excretion of the major melatonin metabolite, 6-sulfatoxymelatonin (6SMT), in infants at high risk for sudden infant death syndrome (SIDS).

Design and Patients: 6SMT was assessed in 43 high-risk infants aged 48-58 weeks post conception (post ALTE -18, infants of drug addicted mothers -9, SIDS siblings -9, high-risk preterm -7) and in 35 healthy infants (matched controls). The high-risk infants were classified as being at high risk (19 cases) or relatively low risk (24 cases) for SIDS. On a double-blind basis, the total excretion of 6SMT by each infant over a 24 hr. period was assessed in urine samples extracted from disposable diapers.

Results: The mean daily excretion of 6SMT was significantly lower in the high-risk (1.64 µg/24 hr) compared to control, healthy infants (3.96 µg/24 hr). The daily excretion of 6SMT in the low-risk infants (3.25 µg/24 hr) did not significantly differ from that in controls. The number of infants producing amounts below the median daily excretion of 6SMT (2.1 µg/24 hr.) was significantly higher in the high-risk (15/19) compared to the low risk (12/24) or healthy infant (12/35) group. Significant elevation of nighttime over daytime excretion was observed in approximately half of the infants in each of the three groups. The low 6SMT excreting infants showed an increase in 6SMT excretion over time which reached the 48-58 weeks median values within 6-8 weeks beyond the study period.

Conclusions: These results suggest that the ontogeny of 6SMT excretion is delayed in infants at high-risk for SIDS, and imply an association between delayed development of the pineal or sympathetic innervation and the risk for SIDS.