Vitamin D supplementation after parathyroidectomy - effect on bone mineral density – a randomized double blind study

Journal of Bone and Mineral Research, 09/27/2013

Patients with primary hyperparathyroidism (PHPT) have higher bone turnover, lower bone mineral density and an increased risk of fractures. They also have a high incidence of low vitamin D levels (25–OH–vitamin D < 50 nmol/l) that could worsen the negative effect on the bone. Except for a minor improvement of radius BMD, the data show no beneficial effect on BMD or bone turnover markers of vitamin D supplementation after PTX. Preoperative PTH seems to have the strongest association with improvement in BMD.

Methods

  • In this double–blinded clinical trial, 150 patients with PHPT were randomized, after successful parathyroidectomy (PTX), to one–year daily treatment with either cholecalciferol 1600 IU and calcium carbonate 1000 mg (D +) or calcium carbonate alone (D –).
  • Bone mineral density (BMD) was measured in the lumbar spine, femoral neck, total hip, distal and 33% radius using dual X–ray absorptiometry (DXA) before surgery and after one year of study medication.

Results

  • Median age was 60 years (30–80 years) and there were 119 (79%) women and 31 (21%) men.
  • 76% had 25–OH–D < 50 nmol/l before PTX.
  • 50% had persistent elevated PTH 6 weeks after PTX.
  • A similar increase in BMD in the lumbar spine, femoral neck and total hip was observed in both groups (D + : 3.6%, 3.2% and 2.7%, p < 0.001; D–: 3.0%, 2.3% and 2.1%, p < 0.001).
  • Patients with vitamin D supplementation also increased their BMD in distal radius (2.0% (–1.7 – 5.4), p = 0.013).
  • The changes in BMD, especially in the hips, were correlated to the baseline concentrations of PTH, ionized calcium and bone markers (p < 0.001).
  • Except for the increase in distal radius BMD, a benefit from vitamin D substitution was observed among patients with a persistent postoperative PTH elevation, who also improved their BMD at 33% radius and radius UD (p < 0.05).

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