Primary hyperparathyroidism: Iliac crest trabecular bone volume, structure, remodeling, and balance evaluated by histomorphometric methods

Abstract

Iliac bone biopsies from 69 patients (48 females, 21 males; median age 58 years; range 17–79 years) with primary hyperparathyroidism (PHP) were examined, and static histomorphometric parameters compared to 30 age- and sexmatched normal controls. The control group for the dynamic parameters constituted 20 sex-matched younger normal controls. Fractional volume of trabecular bone was normal, but the trabeculae were thinner ( p < 0.05) in PHP. The structural parameters marrow space star volume, intertrabecular distance, and mean trabecular plate density were not significantly different in PHP patients compared to normal controls, but the age-related increase, for females, in marrow space star volume and decrease, for both sexes, in mean plate density observed in the controls were not noticed in the PHP group. Trabecular bone remodeling was found significantly increased in the PHP patients reflected by increased extension of eroded ( p < 0.001), osteoid ( p < 0.001), and labeled surfaces ( p < 0.05). The activation frequency was increased by approximately 50% ( p < 0.001). Neither PHP patients nor controls showed age-related decrease in trabecular thickness, and accordingly in both groups the bone balance per remodeling cycle was very close to and not significantly different from zero. Normal postmenopausal women (age ≥ 50 yr) had lower trabecular bone volume ( p < 0.001) and higher intertrabecular distance than normal pre-menopausal women (age < 50 yr). This difference was not found for PHP women, indicating that PHP women in some way seem to be protected from the accelerated bone loss seen in normal women in connection with the menopause. It was concluded that due to an enhanced activation frequency, trabecular bone remodeling was increased in PHP. Except for a slight thinning of trabeculae, no changes in trabecular bone structure were found, and the study displayed no indications of an accelerated bone loss. On the contrary, the data suggested conservation of bone volume with aging in PHP.