HYPOTHYROIDISM, THYROXINE TREATMENT, AND THE HEART

Hypothyroidism is a common condition; surveys indicate that approximat ely 1% of the general population and 4% of people 60 years and older a re prescribed thyroxine long term.(1) Hypothyroidism has cardiovascula r consequences resulting from both direct influences of thyroid hormon e deficiency on the heart, and adverse effects on circulating lipid co ncentrations. Furthermore, with the advent of improved tests of thyroi d function, it has become clear that even when patients with hypothyro idism are treated with thyroxine long term, about half have serum thyr otrophin concentrations above or below the normal range, indicating a degree of under or over treatment with thyroxine. Although little impo rtance has been attached to these minor biochemical abnormalities, rec ent evidence suggests that they may have considerable clinical signifi cance.