Endocrine Abstracts

Background: Bisphosphonates are capable of suppressing parathormone (PTH)-mediated bone resorption and can be used as an adjunct treatment in acute hypercalcemia. We investigated the effects of oral alendronate on bone mineral density (BMD) and biochemical markers of calcium and bone metabolism in patients with primary hyperparathyroidism (PHPT).

Methods: Twenty-six patients aged 58.5±13.9 years with confirmed PHPT were treated with alendronate (70 mg once a week) for 1 year. The patients were low symptomatic or symptomatic and were unwilling to have parathyroid surgery. Five patients underwent previously unsuccessful parathyreoidectomy.

Results: After 1 year of treatment, mean BMD increased significantly at lumbar spine (2.5%), femoral neck (1.8%), ultradistal part of the forearm (3.2%) and total body (2.2%), but not at the distal part of the forearm. The highest increases in BMD were in the lumbar spine (13.4%) and ultradistal part of the forearm (17%). In some patients BMD decreased despite taking alendronate. Changes in BMD were not correlated with serum PTH, 25-OH vitamin D, baseline BMD values or age of the patients. PTH did not change with alendronate treatment (mean±S.E.M.: 164±13 vs 144±10.5 pg/ml of baseline value, reference range: 11–67 pg/ml). Serum calcium, and urinary calcium excretion did not change significantly from the baseline values. Mean alkaline phosphatase concentration decreased significantly.

Conclusions: Our results suggest that alendronate may be effective in decreasing bone resorption in some patients with PHPT and does not affect PTH or serum and urine calcium. The greatest increase in bone density occurs at ultradistal part of the forearm and lumbar spine: sites with a high content of trabecular bone which is more metabolically active than cortical bone.

Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.

Funding: This work was supported, however funding details unavailable.