Beneficial effect of thyroidectomy in canine hemorrhagic shock

To further evaluate the relationship between plasma thyroid hormone concentrations and mortality in shock, 10 thyroidectomized and 9 normal dogs were bled rapidly to a mean arterial pressure of 40 mm Hg. After 60 min of hypotension, the reservoir line was clamped for 30 min. The shed blood was then reinfused. Thyroidectomy produced a hypodynamic, hypometabolic state. During shock, these animals exhibited fewer major hemodynamic derangements than the control group. Only one thyroidectomized dog died, whereas 5 of 9 control animals died (p less than 0.05). Thus, circulating thyroid hormones are not determinants of survival in canine hemorrhagic shock. We hypothesize that thyroidectomy, perhaps by modulating catecholamine metabolism or stimulating liberation of thyrotropin releasing hormone, promotes salutary hemodynamic-metabolic effects during circulatory collapse and enhances survival.