Endocrine Abstracts

Osteoprotogerin (OPG) and the receptor activators of nuclear factor-kβ (RANK) and nuclear factor-kβ ligand (RANKL) play an important role in bone metabolism. RANKL binds to RANK, which is expressed by osteoclasts, whereas OPG acts as its decoy receptor, blocking the RANK–RANKL interaction.

The aim of our study was to evaluate bone turnover parameters (serum calcium, phosphorus, alkaline phosphatase, parathormone, osteocalcine, 24-h urinary calcium level, urinary deoxy-pyridinoline), osteoporosis-associated cytokines (IL-1β, IL-6, TNFα), RANKL and OPG serum levels in patients with overt hyperthyroidism before antithyroidal treatment (while in the hyperthyroid state) and after achieving euthyroidism. Forty-six patients (30 men, 37% pre-menopausal women, 33% postmenopausal women) participated in this observational study: 22 with Graves’ disease (mean age 38±5 years), 14 with toxic multinodular goiter (mean age 55±4 years) and 10 with toxic adenomas (mean age 44±12 years). Serum levels of bone formation and resorption markers were abnormally high before treatment and decreased to normal levels as the patients became euthyroid. However, no significant change was observed at osteoporosis-associated cytokine levels and RANKL and OPG levels (0.36±0.05 vs 0.35±0.05 and 6.5±3.1 vs 6.4±3.0 pmol/l, respectively) in these endogenous hyperthyroid patients.

In conclusion, although endogenous hyperthyroidism increases the levels of bone formation and resorption markers, no change is observed in the serum levels of osteoporosis-associated cytokines, RANKL and OPG.