The effects of thyroid status on serum apolipoprotein A-I-containing lipoprotein particles

Alterations of lipid profile are a well-known phenomenon in thyroid dysfunction. However, little is known about the influence of thyroid hormone on Lp A-I and LpA-I:A-II particles. We have, therefore, studied LpA-I and LpAI:A-II concentrations in a group of 20 patients with hyperthyroidism and in a group of 15 patients with hypothyroidism before and one month after attainment of euthyroidism. In hypothyroid patients, LDL-cholesterol and apo B concentrations decrease significantly after L-T4 replacement treatment (from 4.49+/-2.51 to 2.76+/-0.70 mmol/ L, P=0.036 and from 89.4+/-16.1 to 78.3+/-13.3 mg/dL, P=0.05, respectively), whereas no significant change was observed in the total cholesterol, HDL-C, LpA-I, LpA-I:A-II and apo A-I concentrations. In hyperthyroid patients, total cholesterol (from 3.58+/-0.72 to 4.74+/-1.39mmol/L, P=0.0025), HDL-C (from 1.19+/-0.23 to 1.41+/-0.27mmol/L, P=0.0084), LDL-C (from 1.83+/-0.69 to 2.96+/-1.20 mmol/l, P=0.0025), apo A-I (from 85.6+/-12.5 to 91.7+/-18.1 mg/dL, P=0.05) and apo B (from 52.7+/-8.2 to 65.6+/-16.5 mg/dL, P=0.0013) increased after restoration of euthyroidism while triglycerides, LpA-I and LpA-I: A-II concentrations were unchanged. LpA-I and LpA-I:A-II concentrations were not related to thyroid hormones in both groups. Our study suggests that LpA-I and LpA-I:A-II particles are not under the direct control of thyroid hormones.