Changes in levels of thyroid hormones and TSH in acute myocardial infarction.

The changes in levels of total serum thyroxine (T4), total serum triiodothyronine (T3), effective thyroxine ratio (ETR), and serum TSH were investigated in 88 patients with acute myocardial infarction (AMI). The T4 and T3 values decreased significantly on the third day of hospitalization to return to starting values on the 7th day. ETR values were significantly reduced on the 3rd day and remained so also on the 7th day. Compared to starting values, serum TSH levels were increased on the 7th day of hospitalization, yet not significantly. In the group of 16 patients who died within 96 hours, ETR values were significantly increased on the 1st day of hospitalization (immediately after admission) in comparison with the group of AMI surviving patients. The highest frequency rate of abnormally low T3 values was found in patients who died within 96 hours. With respect to thyroid function evaluation, ETR proved to be the most satisfactory parameter with the lowest percentage of abnormal values.