Microstructure of the trabecula and cortex of iliac bone in primary hyperparathyroidism patients determined using histomorphometry and node-strut analysis.

The purpose of this study was to use histomorphometry to compare the microstructure of trabecular and cortical bone in patients with primary hyperparathyroidism (PH) with that seen in osteoporosis. Histomorphometric and node-strut analyses of iliac bones were performed on 11 female patients with PH (61.3 +/- 8.0 years old) and 61 age-matched female patients with involutional osteoporosis (OP) (63.6 +/- 5.6 years old). Cancellous bone volume (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), trabecular separation (Tb.Sp), and wall thickness (W.Th) were not significantly different in these two groups. The bone formation rate (BFR) tended to be higher in the PH group than in the OP group. The number of nodes (N.Nd/TV) and node-to-node strut length (Nd.Nd/TV) were significantly higher in the PH group than in the OP group. The number of termini (N.Tm/TV) and terminus-to-terminus strut length/total strut length (Tm.Tm/TSL) were significantly lower in the PH group; cortical porosity was significantly higher in the PH group than in the OP group. No correlation was found between age and N.Nd in the PH group, but there was a negative correlation between age and N.Nd in the OP group. Our results show that trabecular connectivity was maintained while cortical porosity deteriorated in patients with PH compared with OP. These results suggest that there are microstructural differences between PH and OP in cancellous and cortical bone that result from the bone remodeling sequence in humans.