Increased bone apposition in primary hyperparathyroidism: measurements based on short interval tetracycline labeling of bone.

Bone biopsies of 23 subjects suffering from primary hyperparathyroidism, which was proven by the demonstration of parathyroid pathology during neck surgery, were studied by morphometric analysis and short interval sequential tetracycline labelling and compared with those of 13 patients without metabolic bone disease. In 19 of these patients, abnormalities were found in the trabecular volume, resorption surface, formation surface, or in various combinations. However, no constant pattern of bone changes was observed. In 4 patients, the bone morphometric parameters were normal. The bone apposition rate, on the other hand, was elevated in all 23 subjects. The rate was re-evaluated in 4 patients 6 wk to 3 mo following successful parathyroid surgery. It fell back within the control range. These findings confirm the observation in experimental animals that parathyroid hormone stimulates bone apposition in vivo and give support to the rationale of using this hormone in the treatment of osteoporosis.