Endocrine Abstracts

Introduction: Osteoporosis is a frequent complication associated with primary hyperparathyroidism (PHPT), and surgery is the most effective treatment once established. However, many patients are not candidates for it, and different medical options have been investigated. We aimed to assess the efficacy of denosumab (DMAB) in increasing bone mineral density (BMD) and preventing PHPT-related complications.

Methods: Case-control study defining cases (Group 1 G1) as those patients who received DMAB and control (Group 2 G2) as those who had undergone surgery or had received bisphosphonate treatment.

Results: 17 patients of G1 with a mean age of 75,71 years and 56 patients of G2 with a mean age of 62,90 years (P<0,0001) were recruited. The mean follow-up time for G1 was 2 years and for G2 was 3,2 years. At baseline total serum calcium and normalized ionic serum calcium mean were 9,77 mg/dl and 1,34 mmol/l in G1 vs 10,32 mg/dl and 1,44 mmol/l in G2 (P= 0,001). PTH mean level was 80,88 pg/ml in G1 and 108,89 in G2 (P=0,008). 8 (47.06%) patients from G1 vs 11 (19.64%) patients from G2 had undergone parathyroidectomy before follow-up (P=0,024), and 2 (11.76%) patients from G1 vs 25 (44.64%) patients from G2 underwent surgery during follow-up (P=0,01). At the follow-up end levels of total calcium and ionized calcium decreased -1,52% and -1,81% in G1 vs -8,44% and -14,54% in G2. PTH levels increased 61,64% in G1 and decreased 28,04% in G2. Patients showed an increase in BMD at the lumbar spine by 6.51% in G1 and 4.63% in G2. In the distal third of the radius, BMD decreased by 0.29% in G1 and 0.25% in G2 (P=0,986). Only in G2 did BMD increase by 4.04% in the femoral neck and 2.42% for the total neck. No skeletal fractures or treatment-related adverse events were observed during the follow-up. Only 26.79% of patients in G2 had nephrolithiasis after follow-up.

Conclusions: Denosumab treatment is safe and effective in preserving BMD, especially in the lumbar spine in those patients with PHPT who have a contraindication to undergo parathyroidectomy.