[Low serum TSH levels in patients with emergent conditions due to ischemic heart disease or congestive heart failure].

We investigated the pathophysiological and clinical significance of thyroid stimulating hormone (TSH) levels in patients within 4 days after onset of ischemic heart disease (IHD) or aggravation of congestive heart failure (CHF) due to myocardial infarction. We classified patients into 3 groups: 1) angina pectoris (AP) group [n = 66, 62 years (Mean)], 2) acute myocardial infarction (AMI) group (n = 58, 65 years) and 3) CHF group (n = 16, 68 years). Soon after admission, blood samples were obtained to measure TSH by the IRMA method. Blood samples for creatine phosphokinase (CPK) were obtained every 3 hours. All patients showed TSH levels that were normal or below normal. Those in whom TSH levels were below normal, were defined as "low TSH" patients. The incidence of low TSH patients in the CHF group (31.3%) was significantly higher (p < 0.05) than that in the AP group (4.5%). In the AMI group, plasma CPK activity of 5037 +/- 1102 U/l (Mean +/- SEM) in low TSH patients were significantly higher (p < 0.05) than that of 1931 +/- 255 U/l in patients with normal TSH levels. These results indicate that in patients with extensive myocardial cell damage, "low TSH" frequently develops during emergency.