Assessments were made of 945 consecutive hospital patients with regard to a relation between borderline low thyroid function (recognised by a slightly raised thyroid stimulating hormone), thyroid autoimmunity, serum cholesterol, and coronary heart disease. Men and women with a thyroid autoimmunity, serum cholesterol, and coronary heart disease. Men and women with a thyroid stimulating hormone of 4.0 mU/l or over had a higher prevalence of coronary heart disease than did age-matched controls, and this difference was significant in women. The excess of coronary heart disease was not explained by an excess of other risk factors such as a high cholesterol, hypertension, smoking, and diabetes. Women with thyroid antibodies had a slightly higher prevalence of coronary heart disease despite the unexpected finding of a lower serum cholesterol. The data point to an association between borderline thyroid function and autoimmunity and coronary heart disease which is not mediated through a raised serum cholesterol.

We have measured basal thyrotropin (TSH) in 945 consecutive patients of a general medical department. Additional thyroid tests were carried out in patients with elevated TSH. Thirty patients (3.1%) had subclinical hypothyroidism, i.e. an elevated TSH with no clinical signs and with a normal free thyroxine index. A cause was found in only fifteen of these thirty patients. Thirteen additional patients (1.37%) had mild or overt primary hypothyroidism, three of which were already diagnosed. This prevalence is three times higher than that found in a retrospective survey at the same hospital. Of the ten newly-detected cases five were discharged on thyroid hormone replacement. In two patients the antithyroid drugs which were the cause of hypothyroidism were discontinued. The remaining three patients had severe non-thyroidal illnesses and thyroid hormone was not prescribed. A cause for the hypothyroidism (autoimmune thyroid disease, post-radioiodine, post-thyroidectomy or antithyroid drugs) was established in all but two cases. The data suggest that thyroid function tests (preferably a TSH) should be performed on any patient with prior treatment to the thyroid and, in addition with very broad indications, perhaps even routinely, in all women over 50 years of age.