THE EFFECTS OF THYROID STATUS ON SERUM APOLIPOPROTEIN A-I-CONTAINING LIPOPROTEIN PARTICLES

Alterations of lipid profile are a well-known phenomenon in thyroid dy sfunction. However, little is known about the influence of thyroid hor mone on Lp A-I and LpA-I:A-II particles. We have, therefore, studied L pA-I and LpAI:A-II concentrations in a group of 20 patients with hyper thyroidism and in a group of 15 patients with hypothyroidism before an d one month after attainment of euthyroidism. In hypothyroid patients, LDL-cholesterol and apo B concentrations decrease significantly after L-T-4 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 tota l 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 +/- 1.39 mmol/L, P = 0.0025), HDL-C (from 1.19 +/- 0.23 to 1.41 +/- 0. 27 mmol/L, P = 0.0084), LDL-C (from 1.83 +/- 0.69 to 2.96 +/- 1.20 mmo l/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 = 0.00 13) increased after restoration of euthyroidism while triglycerides, L pA-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.