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

Patients with primary hyperparathyroidism (PHPT) have higher bone turnover, lower bone mineral density (BMD), 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. In this double-blinded clinical trial, 150 patients with PHPT were randomized, after successful parathyroidectomy (PTX), to 1-year daily treatment with either cholecalciferol 1600 IU and calcium carbonate 1000 mg (D+) or calcium carbonate alone (D-). BMD was measured in the lumbar spine, femoral neck, total hip, distal and 33% radius using dual-energy X-ray absorptiometry (DXA) before surgery and after 1 year of study medication. Median age was 60 (range 30-80) years and there were 119 (79%) women and 31 (21%) men; 76% had 25-OH-D <50 nmol/L before PTX and 50% had persistent elevated parathyroid hormone (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, respectively; and D-: 3.0%, 2.3%, and 2.1%, respectively, p<0.001). Patients with vitamin D supplementation also increased their BMD in distal radius (median 2.0%; interquartile range, -1.7% to 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). 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 ultradistal (p<0.05). In conclusion, except for a minor improvement of radius BMD, our 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.