Changes in plasma concentrations of osteoprotegerin before and after levothyroxine replacement therapy in hypothyroid patients.

Abstract

Recent study has shown that overt hypothyroidism (oHT) is associated with increased plasma osteoprotegerin (OPG) levels. Our objective was to examine the plasma OPG level alteration before and after levothyroxine (L-T4) treatment in oHT and subclinical hypothyroidism (sHT). The study subjects included oHT and sHT patients and healthy individuals (20 subjects in each group). All patients were given L-T4 therapy to maintain a euthyroid state. Plasma OPG concentration was measured in duplicate by a sandwich ELISA. Plasma OPG levels in oHT and sHT before treatment were significantly higher than levels in controls (P < 0.01). After normalization of thyroid function, OPG levels in both groups decreased markedly (P < 0.01). The absolute changes in OPG showed a significant positive correlation with the changes in TSH (P < 0.05) and negative correlation with the changes in endothelium-dependent arterial dilation (P < 0.01) in hypothyroid patients during the course of treatment. OPG may be involved in the development of vascular dysfunction in hypothyroid patients.