Trabecular bone mineralization lag time determined by tetracycline double-labeling in normal and certain pathological conditions.

Quantitative histomorphometric analyses of iliac crest biopsy specimens were performed after tetracycline double-labeling in 41 normal individuals, 20 hyper- and 10 hypothyroid patients, 18 patients with primary hyperparathyroidism, 20 epileptic patients receiving long-term anticonvulsant therapy, and 17 patients after jejunoileal bypass for morbid obesity. The mineralization lag time in trabecular bone or the period of time between apposition and subsequent mineralization of osteoid was calculated from the bone formation rate at BMU level (Basic Multicellular Unit) and the mean width of osteoid seams. The mineralization lag time was 8-52 days (median 21 days) in normal individuals and showed no variation with sex or age. The mineralization lag time was shortened in hyperthyroidism, normal in anticonvulsant bone disease and in primary hyperparathyroidism, and markedly prolonged in hypothyroidism and following jejunoileal bypass. Among all individuals an inverse hyperbolic relation (r = 0.94, p less than 0.001) was found between the mineralization lag time and the average cellular activity of the osteoblasts.