1-34 PTH Could Reverse Impaired Bone Mineralization Induced By the Overdose of Bisphosphonate

ABSTRACT

Bisphosphonates are the mainstay of osteoporosis treatment. Despite the fact that bisphosphonates have a relatively good safety record and are tolerated well by the majority of patients, serious adverse events have been associated with their use. A 41-year-old man had been diagnosed with osteoporosis and had taken etidronate 200 mg/day daily for 2 years due to the judgmental error. He was referred for the management of refractory bone pain and generalized muscle ache. Serum calcium, phosphate, 25-hydroxy-vitamin D (25(OH)D), and immunoreactive parathyroid hormone (iPTH) were within normal range. Plain X-ray showed multiple fractures. Whole body bone scan confirmed multiple sites of increased bone uptakes. Tetracycline-labeled bone biopsy showed typical findings of osteomalacia. He was diagnosed with iatrogenic, etidronate-induced osteomalacia. The patient received daily parathyroid hormone (PTH) injection for 18 months. PTH effectively reverses impaired bone mineralization caused by etidronate misuse. Currently, he is doing well without bone pain. Bone mineral density significantly increased, and the increased bone uptake was almost normalized after 18 months. This case seems to suggest that human PTH (1-34) therapy, possibly in association with calcium and vitamin D, is associated with important clinical improvements in patients with impaired bone mineralization due to the side effect of bisphosphonate.