[Study of thyroid function parameters and thyrotropin in general non-thyroid diseases].

The changes in the parameters of thyroid function and thyrotropin (TSH) have been evaluated in 5 groups of patients with general non-thyroid disease (GNTD): acute severe bacterial infection (16 patients), acute myocardial infarction (22 patients), diabetic ketoacidosis (24 patients), non-ketotic hyperosmolar decompensation (8 patients), protein-calorie undernutrition (12 patients), without associated conditions or drug therapies that might have modified the thyroid hormones. These patients were evaluated at the beginning of their GNTD and after recovery. Thyroxine (T4), triiodothyronine (T3) and reverse T3 (rT3) were measured by radioimmunoassay (RIA), the TBC index by competitive analysis, the free T4 by a labeled T4 analogue and T4 by immunoradiometric analysis (IRMA). In all patients similar changes in thyroid hormones and in IRMA were found, and they returned to normal after recovery; the changes were most marked in diabetic ketoacidosis, followed by hyperosmolar decompensation and by undernutrition. When the 5 groups were evaluated together, T3 was the most commonly low value (57.3%), followed by T4 and TBC index (26.8%), free T4 (20.7%) and the free T4 index (10.9%). The level of rT3 was increased in 39% of cases. Baseline TSH was, initially, 1.05 +/- 1.05 microU/ml, and 1.36 +/- 0.85 microU/ml after recovery (p less than 0.001). It was only found to be suppressed in one patient (a female with diabetes mellitus and Graves disease); in 17 cases it had borderline values between 0.1 and 0.4 microU/ml, and in the remaining patients it was normal. GNTD induces profound changes in the thyroid functional parameters, with reductions below their normal range, including the analogue measured T4 and low TSH.(ABSTRACT TRUNCATED AT 250 WORDS)