Trabecular bone remodeling and balance in primary hyperparathyroidism.

The total remodeling sequences in 19 primary hyperparathyroid patients and 16 approximately age-matched and sex-matched controls were reconstructed from histomorphometric analyses of bone specimens obtained after intravital tetracycline double labeling. In the primary hyperparathyroid group the total amount of work performed by resorptive cells was reduced, as indicated by the significantly lower three-dimensional mononuclear and preosteoblast-like cell resorption depths (35.8 microns vs 44.5 microns in normals, P less than 0.01 and 45.3 microns vs 56.6 microns in normals, P less than 0.01, respectively). The active resorption period (i.e., the function period for osteoclasts and mononuclear cells) was reduced to 19 days compared to 29 days in normals (P less than 0.05), but no difference with respect to bone resorption rates could be demonstrated between the two groups. The median bone formation period (Sigmaf) in primary hyperparathyroid patients was not different from the value obtained in normals (172 days vs 134 days, respectively), and the matrix appositional rate (Ama), as well as the mineralization lag time (tm), were also unchanged. The initial mineralization rate (Ami(i)) was not significantly different from the value obtained in normals, but averaged over the total bone formation period, a reduced mineralization rate could be demonstrated (0.32 micron3/micron2 per day vs 0.46 micron3/micron2 per day in normals, P less than 0.01). The measured final three-dimensional thickness of bone formed during Sigmaf (mcwTm) was reduced in the primary hyperparathyroid group (51.1 microns vs 55.9 microns in normals, P less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)