PRIMARY HYPERPARATHYROIDISM - ILIAC CREST CORTICAL THICKNESS, STRUCTURE, AND REMODELING EVALUATED BY HISTOMORPHOMETRIC METHODS

Iliac crest bone biopsies from 62 patients (42 women, 20 men; median a ge 59 years; range 17-79 years) with primary hyperparathyroidism (PHP) were examined. Static and structural parameters were compared with 30 age- and sex-matched normal controls. Eighteen sex-matched younger co ntrols were used for evaluation of the dynamic controls. On the endoco rtical surface increase in extension of eroded (p < 0.01) and formativ e (p < 0.01) surfaces was found in PHPs compared with normals. Endocor tical bone formation rate was increased in PHPs (p < 0.05), but minera l appositional rate and adjusted appositional rate were normal. On the periosteal surface very little remodeling activity was found. Althoug h bone formation rate was found increased in PHPs (p < 0.05), more tha n half of the labeled biopsies were without periosteal tetracycline in patients, and only 2 of 18 biopsies from normals contained periosteal tetracycline labels. No significant decreases in cortical width or re lative cortical width were found in PHPs. In both patients and control s an age-related decrease in relative cortical width was noted for wom en (PHPs: r = -0.52, p < 0.01; controls: r = -0.59, p < 0.001), but no t for men. Cortical porosity was about 30% increased in PHPs (p < 0.02 ). Only normal women showed a positive age-related increase in porosit y (r = 0.61, p < 0.05). In a group of nine patients with bone biopsies performed 6 to 12 months after surgery significant decreases in poros ity (p < 0.02), eroded surface (p < 0.02), and osteoid surface (p < 0. 02) were noted. Premenopausal women with PHP had increased values of e roded (p < 0.05) and formative (p < 0.05) surfaces as well as of poros ity (p < 0.05) compared with controls, but for the postmenopausal grou p these differences were not statistically significant. In spite of in creased remodeling activity on endocortical, periosteal, and Haversian envelopes, cortical width seemed to a large extent to be preserved in the patients. The cortical bone, though, might be weakened by increas ed porosity and, because of the increased remodeling activity, by an i ncreased amount of new and lightly mineralized cortical bone.