Evaluation of pituitary-thyroid axis response to acute myocardial infarction

We have studied with seriated controls for a period of 9 days 18 patients admitted to our hospital for acute myocardial infarction (AMI). Slight, but non significant variations in thyroidal hormone pattern were observed: slight decrease of T3 and T4 levels, increase of reverse T3 on day 3, low free T4 levels, slight increase of TSH levels until the 3rd day. However, hormonal pattern was clearly different in patients who presented a clinical improvement (group 1a) and in patients who died for AMI (group 1b). In fact, a significant TSH increase was recorded in patients of group 1a; on the contrary, a significant decrease of TSH, T4 and free T4 concentrations was observed for subjects of group 1b, suggesting an inadequate response of pituitary-thyroid axis. In conclusion, the evaluation of thyroid hormones and thyrotropin levels can be of clinical usefulness in the management of patients with AMI. The decrease of plasma T4 and free T4 concentrations, accompanied with low TSH levels, can be associated with unfavorable course of the disease and therefore can be considered a bad prognostic sign.