Mode of death and post-mortem time effects on 3,3',5-triiodothyronine levels--relevance to elevated post-mortem T3 levels in SIDS

Post-mortem T3 levels have been reported to be increased in victims of SIDS. Recent animal studies suggest, however, that elevated T3 in SIDS may be a non-specific post-mortem phenomenon. Therefore, we studied the possible effects of post-mortem time on T3 levels in 10- and 20-day-old rats killed by various methods including: Sodium pentobarbital overdose, injection of KCl, cervical dislocation or asphyxia with 100% N, 95% N-5% CO2 or 100% CO2. In both age groups T3 remained unchanged or increased slightly when the animals were killed with Na Pentobarbital or KCl. Greater increases were observed when rats were killed by cervical dislocation or asphyxia (100% N, 95% N-5% CO2 or 100% CO2). T3 levels did not become elevated in asphyxiated adult rats in which the inferior vena cava was ligated immediately following death. By extension to the human infant, the results of this study support the possibility that elevated T3 levels in SIDS victims may result from post-mortem processes. However, these results also suggest that the post-mortem elevation in T3 levels may be directly related to the mode of death.