Disturbed Lipid Metabolism in Patients with Subclinical Hypothyroidism: Effect of L-Thyroxine Therapy

Abstract

To evaluate whether patients with subclinical hypothyroidism have a disturbance in lipid metabolism, and whether supplemental L-thyroxine (L-T₄) therapy would improve their lipid parameters, we measured serum levels of thyroid hormones, TSH and lipid parameters in 34 patients with subclinical hypothyroidism before and 2 months after treatment with L-T₄. Before treatment, patients with subclinical hypothyroidism had elevated serum low density lipoprotein cholesterol (LDL-C) concentrations compared with control subjects (P<0.05). Overall, L-T₄ therapy significantly decreased the serum level of TSH (P<0.01), total cholesterol (TC; P<0.02), high density lipoprotein cholesterol (P<0.02), LDL-C (P<0.05), and the ratio of apolipoprotein B to apolipoprotein Al (P<0.05). Lipid values in patients with basal serum TSH levels below 10 mU/l were not affected by L-T₄ therapy, whereas serum levels of TC and LDL-C decreases significantly (P<0.01) in patients with serum TSH levels above 10 mU/l. Thus, the L-T₄ treatment appears to have a preventive effect on the disturbance of lipid metabolism in patients with subclinical hypothyroidism, especially in patients with serum TSH levels above 10 mU/l.
(Internal Medicien 33: 413-417, 1994)