Changes in thyroid hormone parameters after acute myocardial infarction.

Abnormalities in circulating thyroid hormone levels are very common in systemic nonthyroidal illnesses, such as acute myocardial infarction. In this study, thyroid parameters were determined in a series of 16 consecutive infarction patients treated by thrombolysis. Blood samples were taken before therapy as well as 2, 4, 6, 8, 12 and 72 h following admission. Total and free serum thyroxin and triiodothyronine decreased and reverse T3 increased significantly showing no major variations up to 72 h, whereas thyroid-stimulating hormone values remained almost unchanged during the observation period. Subjects with CK-MB levels of more than 150 ng/ml (n = 10) revealed similar changes in thyroid parameters in comparison to those with lower values (n = 6; NS). Thus, although hormone modifications very often occur following acute infarction, thyroid status may not serve as a marker for the extent of left ventricular dysfunction in the early phase of myocardial infarction.