Patients with primary hyperparathyroidism (pHPT) with osteopenia and osteoporosis are treated with strontium ranelate/Ca+Vitamin-D or placebo/Ca+Vitamin D after successful surgical treatment of pHPT.

Strontium ranelate/Ca + Vitamin-D helps to regain bone mass in patients with osteopenia or osteoporosis after successful parathyroidectomy for pHPT and results in higher gain of BMD than placebo treated patients.

The chronic excessive hypersecretion of parathyroid hormone (PTH) has significant impact on bone remodeling. In primary hyperparathyroidism (PHPT) bone turnover is increased, resulting in a higher resorption of bone and thus loss of bone density.

After successful surgical treatment of pHPT bone metabolism switches from catabolic state to anabolic state again. However studies show that especially postmenopausal women regain significantly less BMD but these women suffer from osteopenia and osteoporosis most often and would need to regain as much bone mass as possible to prevent fractures. The optimal state would be to reach normal BMD again. Although this state is hardly reachable especially these patients may benefit from a treatment acting anti-resorptive and rising bone formation. The only drug combining these qualities known so far is Strontium ranelate.

Therefore the hypothesis is that Strontium ranelate/Ca + Vitamin-D helps to regain bone mass in patients with osteopenia or osteoporosis after successful parathyroidectomy for pHPT and results in higher gain of BMD than placebo treated patients.

Inclusion Criteria:

• biochemically proven PHPT, PTX planned
• osteopenia (t-score < -1 and > -2.5) or osteoporosis (t-score ≤ -2.5) according to WHO Criteria [27]

Exclusion Criteria:

• Premenopausal women
• Cancer (lung, breast, prostatic, parathyroid cancer and thyroid carcinoma >1cm)
• Persisting or recurrent PHPT (postoperative hypercalcemia)
• Four-gland hyperplasia
• Multiple endocrine neoplasia (MEN) or hereditary PHPT
• Familial hypocalciuric hypercalcaemia (Ca/creatinine ratio < 0.01)
• Anamnestic pulmonal embolism or deep venous thrombosis
• Blood coagulation disorder or coagulopathy
• Phenylketonuria
• Renal impairment (creatinine clearance <30ml/h)
• Severe hepatic disorder
• Severe systemic disorder
• Thyroid dysfunction
• Immobilisation
• Intake of drugs with potential effects on BMD like glucocorticoids, lithium, estrogen-replacement therapy, selective Estrogen-receptor modulators (sERMs), bisphosphonates in the last three months
• Known allergy against any component of the study medication