[Comparative histologic and hormonal studies of the thyroid gland with special reference to sudden infant death...

In 53 cases of death - including 12 cases of sudden infant death syndrome (SIDS) - where blood samples could be taken within 18 h postmortem, the thyroxines T4, FT4, T3 and FT3 were determined (ELISA and RIA). These hormone values were compared with the corresponding histological thyroid findings in 43 cases (11 SIDS, 32 controls). Nearly identical T4 and FT4 mean values were found in both groups which were within the norms. In contrast to the average values of the control group, the T3 and FT3 concentrations of the SIDS group showed an increase of 3.7-fold and 1.9-fold. Accordingly, histological examination of the SIDS group showed highly activated and extensively released follicles whereas normal colloidal-containing follicle structures were observed in nearly all control cases. The present findings indicate that neither postmortem T4 T3 conversion nor intensified agonal hormone secretion is likely to be the only cause of the increasing T3 and FT3 values. In SIDS cases chronic or recurring chronic stress situations are supposed to be the cause for the hormonal and histological thyroid findings. Some differential diagnoses are discussed. Within 18 h after death, increased concentrations of T3 and FT3, together with simultaneous colloid release, represent a diagnosis of SIDS.