HYPERLIPIDEMIA IN PATIENTS WITH PRIMARY AND SECONDARY HYPOTHYROIDISM

Hypothyroidism is associated with an increased risk of coronary artery disease. This observation may in part be related to the lipid abnorma lities in patients with this condition. The lipid profiles of 268 pati ents with primary hypothyroidism and 27 with secondary hypothyroidism, who were examined in the Thyroid Clinic at the Mayo Clinic during a 1 -year period, were reviewed. Hyperlipidemia was commonly associated wi th both primary and secondary hypothyroidism. The lipid values decreas ed with treatment of hypothyroidism. Type IIa hyperlipidemia was the m ost common lipid abnormality in patients with primary hypothyroidism, whereas type IIb was the most common in those with secondary hypothyro idism. Total/high-density lipoprotein cholesterol and low-density lipo protein/high-density lipoprotein cholesterol ratios were increased in both male and female patients with primary and secondary hypothyroidis m, and they decreased with restitution of the euthyroid state, althoug h this decrease achieved statistical significance only in female patie nts. Significant associations with total thyroxine were noted for tota l cholesterol and triglycerides and with thyroid-stimulating hormone ( thyrotropin) for total cholesterol and low-density lipoprotein cholest erol. Thus, both primary and secondary hypothyroidism are commonly ass ociated with an atherogenic lipid profile, which improves with replace ment of thyroid hormone. Even after restitution of the euthyroid state , however, the lipid profile remains atherogenic in male patients. In comparison with primary hypothyroidism, the lipid profile is more athe rogenic in secondary hypothyroidism because of the lower high-density lipoprotein cholesterol levels associated with this condition.