DECREASED HDL CHOLESTEROL IN SUBCLINICAL HYPOTHYROIDISM - THE EFFECT OF L-THYROXINE THERAPY

Thyroid function and lipid tests were measured in 29 premenopausal women with subclinical hypothyroidism. This group was compared with 41 euthyroid women matched for age and metabolic parameters. In basal condition there was no difference in thyroid hormone levels between the two groups except for TSH concentration (P<0.01). Total cholesterol, triglycerides and apolipoprotein (apo A1, A2, B) of women with subclinical hypothyroidism were not different from controls. HDL cholesterol was significantly decreased in subclinical hypothyroidism compared to the controls (P<0.01). With thyroxine therapy, normalization of serum TSH was associated with (1) no significant change in total cholesterol and triglycerides, (2) an increase of HDL cholesterol (P<0.01) and apoprotein Al (P<0.05) levels. Total cholesterol/HDL cholesterol ratio was increased in subclinical hypothyroidism (P<0.01). During L‐thyroxine therapy this ratio returned to normal value. Decreased HDL cholesterol concentration might cause coronary heart disease reported in women with subclinical hypothyroidism. © 1990 Blackwell Scientific Publications Ltd.