Treatment of hypothyroidism in elderly patients and in patients with cardiac disease.

Hypothyroidism is often associated with adverse cardiovascular risk factors such as high cholesterol together with hypertension, endothelial dysfunction, and other atherosclerotic cardiovascular risk factors. The changed hemodynamic characteristics result in reduced cardiac index, and the renal perfusion is impaired with hyponatremia, and low renin and aldosterone production. The ischemic abnormalities are probably related to long-term consequences of a slow development of hypothyroidism, while the hemodynamic changes can develop in very short-term hypothyroidism. Replacement of hypothyroidism with levothyroxine is associated with a normalization of basal metabolic rate. Most patients with preexisting angina experience a gradual amelioration of symptoms, but in some cases the initial therapy may precipitate an unrecognized ischemic state, worsen a preexisting angina, or even result in myocardial infarction. It is therefore advisable to start replacement slowly and if needed perform a stress test and/or coronary angiography before. It may also in some cases be necessary to monitor the patients closely in a hospital setting during initiation of levothyroxine. Elderly hypothyroid patients with unstable angina pose a particular challenging problem, especially if coronary vascular surgery is indicated. No increased risk of peri- or postoperative death has been noted in small studies, although more complications have been described. It may be relevant to treat the cardiac vascular occlusion before starting replacement with levothyroxine in some cases, after careful weighting of pros and cons in each individual case.