Postmortem behavior of serum thyroxine, triiodothyronine, and parathormone

Comparison of thyroxine, triiodothyronine, and parathormone levels in antemortem and postmortem sera was done by radioimmunoassay. In all but one of twelve cases, thyroxine levels irregularly declined after death, but this was statistically significant in only five patients. Triiodothyronine was assayed in eleven patients; two levels fell, six rose, and two remained unchanged as late as 17.75 h after death. One patient had a decline in hormone level, followed by an elevation. Five of the eleven patients assayed for parathormone maintained stable levels for as long as 17.75 h after death. Five levels showed an elevation, and one, a decline followed by an elevation. The erratic behavior of triiodothyronine and parathormone after death may be due to conversion from thyroxine or from heterologous forms of parathormone, respectively. It was noted that hormone levels from the inferior vena cava tended to be higher than those from femoral veins, with diffusion of hormone from decomposing glands in the neck as a possible cause.