Abstract
We investigated lecithin cholesterol acyltransferase (LCAT) activity in 31 patients with hyperthyroidism, 25 with hypothyroidism and 66 euthyroid controls who were all females and sex matched. Molar LCAT rate in hyper- and hypothyroid subjects was not significantly different from controls. But fractional LCAT rate was significantly higher in hyperthyroidism but lower in hypothyroidism than in euthyroid control. Esterified cholesterol (E-chol)/free cholesterol (F-chol) ratio showed no significant difference between hyperthyroid and normal subjects but a significant decrease in hypothyroid subjects. After thyroid function became normal by medical treatment, all of these abnormalities were normalized except for E-chol/F-chol ratio in hypothyroidism which remained low. As a conclusion, thyroid hormones seem to have an effect upon LCAT activity. Since serum E-chol levels are influenced by other factors such as lipid transfer protein and hepatic uptake of E-chol however, LCAT activity was not necessarily concordant with E-chol/F-chol ratio.
