The Incidence of Asymptomatic Hypothyroidism in New Referrals to a Hospital Lipid Clinic

As a result of public health and media campaigns there is now considerable public awareness of elevated serum lipids as a risk factor for coronary artery disease. A direct consequence of this has been a great increase in cholesterol screening of asymptomatic individuals; indeed patients detected in this way now constitute a significant proportion of all lipid clinic referrals. Hypercholesterolaemia is a well recognized metabolic consequence of hypothyroidism which will resolve on treatment with L-thyroxine. Before the advent of sensitive biochemical tests of thyroid function, an elevated serum cholesterol concentration was regarded as important supporting evidence in suspected hypothyroidism.’ The development of hypothyroidism is insidious and significant hypercholesterolaemia may develop before the clinical features of hypothyroidism are apparent. In an age of widespread cholesterol screening such patients may present in increasing numbers with hypercholesterolaemia rather than with the more traditional features of hypothyroidism. We assessed the clinical and biochemical thyroid status of new referrals to a hospital lipid clinic. The Lipid Clinic of the Royal Victoria Hospital is a secondary referral centre for the management of dyslipidaemias. Two hundred and twenty new referrals were seen in a one year period. All new referrals undergo a complete physical examination and in particular are assessed with regard to clinical thyroid status by experienced medical staff. A fasting blood specimen is taken for the measurement of total and high density lipoprotein (HDL) cholesterol, triglyceride and for Apoprotein E phenotyping. To exclude a secondary dyslipidaemia, a full biochemistry