Comparisons of serum sclerostin levels among patients with postmenopausal osteoporosis, primary hyperparathyroidism and osteomalacia.

Wnt-β-catenin signaling is important for bone formation. Sclerostin inhibits bone formation mainly by suppressing this signal, and several studies suggest that the suppression of sclerostin expression contributes to the bone anabolic action of parathyroid hormone (PTH). We therefore examined serum sclerostin levels using enzyme-linked immunosolvent assay in 18 patients with postmenopausal osteoporosis, 9 postmenopausal women with primary hyperparathyroidism (pHPT) and 7 patients with osteomalacia. Serum levels of sclerostin were significantly lower in the group with pHPT, compared with those with postmenopausal osteoporosis. Moreover, serum sclerostin levels were significantly lower in the group with tumor-induced osteomalacia, but not in the group with osteomalacia without tumor, compared with those with postmenopausal osteoporosis. In patients with pHPT, serum sclerostin levels were significantly and negatively correlated to serum calcium and PTH levels. In patients with postmenopausal osteoporosis, serum levels of sclerostin levels were significantly and positively related to serum calcium and creatinine levels. In conclusion, we showed that serum sclerostin levels are decreased presumably through endogenous PTH elevation in postmenopausal women with pHPT, compared with the patients with postmenopausal osteoporosis.