A comparison of parathyroid hormone‐related protein (1‐36) and parathyroid hormone (1‐34) on markers of bone turnover and bone density in postmenopausal women: The PrOP study

ABSTRACT Parathyroid hormone‐related protein (PTHrP)(1‐36) increases lumbar spine (LS) bone mineral density (BMD), acting as an anabolic agent when injected intermittently, but it has not been directly compared with parathyroid hormone (PTH)(1‐34). We performed a 3‐month randomized, prospective study in 105 postmenopausal women with low bone density or osteoporosis, comparing daily subcutaneous injections of PTHrP(1‐36) to PTH(1‐34). Thirty‐five women were randomized to each of three groups: PTHrP(1‐36) 400 µg/day; PTHrP(1‐36) 600 µg/day; and PTH(1‐34) 20 µg/day. The primary outcome measures were changes in amino‐terminal telopeptides of procollagen 1 (PINP) and carboxy‐terminal telopeptides of collagen 1 (CTX). Secondary measures included safety parameters, 1,25(OH)2 vitamin D, and BMD. The increase in bone resorption (CTX) by PTH(1‐34) (92%) (p