Hypothalamo-hypophysäre Schilddrüsen-Achse, Plasmaproteinkonzentrationen und die hypophysäre Gonaden-Achse im Low-T3-Syndrom nach akutem Myokardinfarkt (AMI)

Summary

In patients with severely acute diseases, a special relationship of thyroidal hormones with decreased T3 and increased rT3 levels is known, the so-called low T3 syndrome. The aim of this study was to elucidate the involvement of the hypothalamo-pituitary thyroid axis, the pituitary-gonadal axis, the altered hepatic function, the plasma proteins in the low T3 syndrome, and the evaluation of these parameters for prognosis in patients with acute myocardial infarction. Thirty-one patients (29 male, 2 female) with AMI entered the study for the determination of hypothalamo-pituitary thyroid axis and the plasma proteins. Besides routine laboratory determinations, TRH, TSH, T4, T3, rT3, CHE, albumin, total protein, TBG, and estradiol concentrations in plasma were measured daily for 5 days after AMI using immunological and other methods. Twelve male patients with AMI entered the study for the determination of pituitary-gonadal axis; the T3, rT3, estradiol, testosterone, FSH, and LH concentrations in serum were determined using immunological methods. We found that T3 and T4 decreased significantly to a minimum on the first and the second day, respectively, after admission and increased in the course of the observation period. In contrast, rT3 was elevated significantly within the first 2 days and decreased later. TSH and TRH decreased in the first 2 days and increased in the following days. CHE, albumin, and total protein levels significantly showed a minimum on day 4 and TBG significantly showed a minimum on the second day after AMI and increased to day 4. The estradiol and testosterone levels were high on admission and decreased in the following days and increased again in the observation period. FSH decreased in the first 2 days and increased in the following course similar to estradiol and testosterone. Patients who died within 2 weaks after AMI showed a plasma hormonal pattern of hypothyroidism with low TSH levels and hypogonadotropic hypogonadism on the second day, whereas this pattern is persistent in the following days. These results show the involvement of the hypothalamo-pituitary axis in the low T3 syndrome and that characteristics for acute partial insufficiency of the anterior pituitary gland are signs of a bad prognosis. Whether Gn-RH and ACTH also decreased after AMI is unknown. The necessity for substitution is unclear and needs further investigation