Decrease in Bone Formation and Bone Resorption during Intravenous Methylprednisolone Pulse Therapy in Patients with Graves' Orbitopathy

Background: Treatment with glucocorticoids (GCs) is associated with side effects. In contrast to the well-known negative impact on bone tissue exerted by oral GCs, few data are available regarding intravenous GCs. We investigated the influence of intravenous methylprednisolone (IVMP) on bone turnover markers (BTM): amino-terminal propeptide of type I procollagen (P1NP) and the C-terminal telopeptide of type I collagen (CTX), and on calcium metabolism parameters: 1,25-dihydroxyvitamin D (1,25(OH)(2)D), 25-hydroxyvitamin D (25(OH)D), calcium (Ca), phosphate (P), and intact parathormone (iPTH). Methods: In a prospective study, 23 consecutive subjects with Graves' orbitopathy were included and treated with IVMP according to the European Group on Graves' Orbitopathy recommendations. We evaluated effects on BTM occurring during the first 7 days after 0.5 g IVMP, and after the therapy with 12 IVMP pulses with a cumulative dose of 4.5 g. Results: We observed prompt but transient decrease of P1NP (p < 0.001) and the reduction of CTX (p = 0.02) after the first IVMP pulse. Following the full course of IVMP therapy, both P1NP and CTX were found decreased (p < 0.05 and p < 0.01, respectively). Conclusions: A single pulse of 0.5 g IVMP already decreases bone formation and resorption; however, this change is transient. The full therapy is associated with suppression of bone turnover.