Abstract
One hundred nine elderly patients (average age 73) were divided into euthyroid (61), latent hypothyroid (36) and overt hypothyroid (12) according to the clinical signs and the serum TSH and T4 values. The frequency of myocardial infarction in these three groups of patients were compared. Those patients who are asymptomatic with no previous history of thyroid disorders, and with normal serum T4, but with elevated TSH level were defined as latent hypothyroid. On the other hand, patients who are symptomatic and with lowered serum T4, but with markedly elevated TSH levels were defined as overt hypothyroid.
It was found that the frequency of myocardial infarction in latent hypothyroid was approximately three times as high as that in the euthyroid patients. On the other hand, the incidence of myocardial infarction in overt hypothyroid was zero.
Since the age, the incidence of hypertension, diabetes and hypercholesteremia are not significantly different in those three groups, it is possible that latent hypothyroidism could be a new risk factor of myocardial infarction.
