Skeletal changes after restoration of the euparathyroid state in patients with hypoparathyroidism and primary hyperparathyroidism

Restoration of the euparathyroid state is associated with improvement of bone dynamics both in hypoparathyroidism and primary hyperparathyroidism. To date, no study has directly compared these two groups following correction of parathyroid hormone excess or deficiency. The study was designed to investigate changes in bone mineral density and trabecular bone score with restoration of the euparathyroid state by parathyroidectomy in primary hyperparathyroidism or recombinant parathyroid hormone [rhPTH(1-84)] replacement in hypoparathyroidism. This was a 2-year prospective intervention study in which we evaluated areal bone mineral density by DXA and trabecular bone score in 52 hypoparathyroid patients on rhPTH(1-84) replacement and 27 patients with primary hyperparathyroidism who underwent parathyroidectomy. We evaluated changes in areal bone mineral density by DXA and trabecular bone score at baseline, 6, 12, 18, and 24 months. After parathyroidectomy, areal bone mineral density increased from baseline at the lumbar spine and total hip at 6 months and at the femoral neck at 12 months, while there were no changes at the distal 1/3 radius. Treatment with rhPTH(1-84) was associated with significant increases in lumbar spine and decreases in distal 1/3 radius areal bone mineral density by 18 months in hypoparathyroid patients. At this time point, hypoparathyroid subjects demonstrated a significant increase in trabecular bone score from baseline, while there were no significant changes in trabecular bone score following parathyroidectomy. Bone mineral density increases both with administration of parathyroid hormone in a state of parathyroid hormone deficiency or removal of parathyroid hormone in a state of parathyroid hormone excess. However, only hypoparathyroid patients on rhPTH(1-84) appeared to have improvements in micro-architectural pattern as assessed by trabecular bone score.