The effect of adding PTH(1–84) to conventional treatment of hypoparathyroidism: A randomized, placebo-controlled study

Journal of Bone and Mineral Research, 09/29/2011

The need for calcium and active vitamin D is reduced significantly during parathyroid hormone–replacement therapy (PTH–RT), whereas plasma calcium and phosphate levels are maintained within the physiologic range. In contrast to the effect of PTH(1–84) treatment in patients with osteoporosis, PTH–RT in hypoparathyroidism causes a decrease in BMD. This is most likely due to the marked increased bone turnover. Accordingly, PTH–RT counteracts the state of overmineralized bone and, during long–term treatment, may cause a more physiologic bone metabolism.

Methods

  • In a double–blind design, the authors randomized 62 patients with hypoparathyroidism to daily treatment with PTH(1–84) 100 μg or similar placebo for 24 weeks as add on therapy to conventional treatment.
  • Compared with placebo, patients on PTH(1–84) reduced their daily dose of calcium and active vitamin D significantly by 75% and 73%, respectively, without developing hypocalcemia.

Results

  • hypercalcemia occurred frequently during the downtitration of calcium and active vitamin D.
  • Plasma phosphate and renal calcium and phosphate excretion did not change.
  • Compared with placebo, PTH(1–84) treatment significantly increased plasma levels of bone–specific alkaline phosphatase (+226%±36%), osteocalcin (+807%±186%), N–terminal propeptide of procollagen 1 (P1NP; +1315%±330%), cross–linked C–telopeptide of type 1 collagen (CTX; +1209%±459%), and urinary cross–linked N–telopeptide of type 1 collagen (NTX; (+830%±165%), whereas BMD decreased at the hip (–1.59%±0.57%), lumbar spine (–1.76%±1.03%), and whole body (–1.26%±0.49%) but not at the forearm.

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