Sudden infant death syndrome (SIDS) is thought to result from several interacting factors, including underlying disease processes existing from birth. However, there are currently no peripheral biomarkers indicative of the syndrome.
In a paper published in Proceedings of the National Academy of Sciences
(18 July 2017), researchers compared serum serotonin levels in 61 infants who died from SIDS with 15 controls.
Using high-performance liquid chromatography, they found that the mean serum serotonin level was significantly higher in SIDS infants at 177.2ng/ml compared with 91.1ng/ml in control infants. In all, 31% of SIDS infants had elevated serotonin levels.
The researchers say the results add to evidence indicating that serotonin metabolism abnormalities may contribute to SIDS and suggest that serum levels of the neurotransmitter could be used as a biomarker at autopsy to differentiate SIDS deaths with serotonergic defects from other causes of SIDS.
 Haynes R, Frelinger A, Giles E et al. High serum serotonin in sudden infant death syndrome. Proc Natl Acad Sci USA 2017; 114:7695-7700. doi: 10.1073/pnas.1617374114