An Association Between Varying Degrees of Hypothyroidism and Hypercholesterolemia in Women: The Thyroid-Cholesterol Connection.

Evidence of an association between subclinical hypothyroidism and cardiovascular disease is mounting. The impact of thyroid hormone on lipid levels is primarily mediated through triiodothyronine (T(3))-bound thyroid protein binding and activation of the promoter regions of the low-density lipoprotein receptor and 3-hydroxy-3-methylglutaryl coenzyme A-reductase genes, leading to a reduction in serum cholesterol levels. Thus, the decreased T(3) seen in hypothyroidism may result in increased serum cholesterol. Although a clear correlation exists between overt hypothyroidism and clinically significant hypercholesterolemia, there is a logarithmic relationship between thyroid-stimulating hormone and cholesterol, and the effects of subclinical hypothyroidism on cardiovascular disease are under debate. However, current data suggest that normalizing even modest thyroid-stimulating hormone elevations may result in improvement in the lipid profile. (c)2001 CHF, Inc.