The Low T3 Sick Syndrome is a syndrome of low triiodothyronine (T3), low to normal thyroxine (T4), and a nonelevated thyrotropin despite the low T3 levels. This syndrome is frequently encountered in critically ill patients. These same patients are also at higher risk to develop acute stress ulcerations. The objective of this study was to access the effects of low circulating thyroid hormone levels on the development of stress ulcers in the rat. Rats having had previous surgical thyroidectomies were subjected to individual restraint stress; these animals had a significantly increased incidence of stress ulcers when compared to euthyroid stressed controls (1.6 ± 0.4 ulcers vs 0.5 ± 0.2 ulcers per animal, P < 0.05). Surgically thyroidectomized (hypothyroid) animals who were given T3 replacement and then stressed, had ulcer rates similar to normal stressed controls (0.5 ± 0.2 ulcers per animal). We conclude that low circulating thyroid hormones have an ulcerogenic effect, and that replacement of T3 in rats with surgical hypothyroidism reverses this effect.
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