Significance of minimodeling in dialysis patients with adynamic bone disease

We previously concluded from histomorphometric analysis that minimodeling contributes to bone formation in adynamic bone disease in patients with primary hypoparathyroidism. Presently we investigated whether this mechanism might be peculiar to adynamic bone disease.

We histomorphometrically analyzed bone specimens obtained at biopsy or autopsy from 26 maintenance hemodialysis patients with hyperparathyroidism necessitating parathyroidectomy (group A) and from 27 dialysis patients with hypoparathyroidism (group B); respective mean ages were 60 +/- 7 years vs. 64 +/- 8 years; dialysis duration 14 +/- 6 years vs. 11 +/- 9 years; and serum intact parathyroid hormone (PTH) 1205 +/- 439 pg/mL vs. 41 +/- 27 pg/mL. Group B was divided further into outpatient and inpatient subgroups.

By histomorphometry, group A patients were diagnosed with osteitis fibrosa, and those in group B with adynamic bone disease. Minimodeling bone volume and minimodeling bone number were significantly greater in group B than group A (P= 0.0028 and P= 0.0008, respectively). Minimodeling bone volume correlated significantly and positively correlated with total bone volume in group B (P= 0.0016), but not in group A. In group B, minimodeling bone volume and total bone voluem were greater in outpatients than inpatients (P < 0.0001 and P= 0. 025, respectively). Minimodeling bone volume and total bone volume showed significant negative correlation with age in group B (P < 0.001 and P= 0.005, respectively).

Minimodeling might contribute to bone formation in dialysis patients with adynamic bone disease, in the absence of remodeling stimulated by parathyroid hormone (PTH), especially in relatively young patients with good activities of daily living.