Postoperative zoledronic acid for osteoporosis in primary hyperparathyroidism: a randomized placebo-controlled study

In primary hyperparathyroidism (PHPT) with osteoporosis, bone mineral density (BMD) improves after parathyroidectomy. It is unclear whether combining surgery with postoperative bisphosphonate treatment can further improve bone health.

This randomized, placebo-controlled study compared the effects of surgery alone and surgery combined with zoledronic acid on bone metabolism in PHPT with osteoporosis.

Fifty-six patients (f/m 47/9, mean age 68.4 years) with PHPT and osteoporosis were randomized 1-3 months after parathyroidectomy to receive a 2-year treatment of zoledronic acid or placebo. Dual-energy X-ray absorptiometry (DXA) and bone turnover markers (N-terminal propeptide of type 1 procollagen, C-terminal telopeptide of type 1 collagen, and alkaline phosphatase) were measured annually during the 2-year follow-up.

Two years after parathyroidectomy, BMD was significantly higher in the zoledronic acid (ZOL) group compared with the placebo (PBO) group at the femoral neck (P = 0.045 for Z-score) and lumbar spine (P = 0.039 and 0.017 for T- and Z-scores, respectively). Bone turnover markers were significantly lower in the ZOL group (P < 0.001 for all markers). Of the 18 patients who had received bisphosphonates for >1 year before surgery, BMD improved significantly in the ZOL group both in the femoral neck and lumbar spine (n = 10; all P < 0.001-0.01), but in the PBO group, only in the lumbar spine (n = 8, P = 0.03), (P = 0.08-0.95 for between-group changes).

BMD increases after parathyroidectomy both with and without zoledronic acid but the increase is significantly higher with postoperative zoledronic acid.