[Markers of bone formation and resorption in primary and secondary hyperparathyroidism]

Hyperparathyroidism, both primary and secondary in chronic renal failure, leads to pathologic changes in the bones. Newly introduced markers of bone metabolism enable to biochemically detect and evaluate these changes. The aim of our studies was to perform determinations of serum osteocalcin as a marker of bone formation, and C-terminal telopeptide of collagen I (ICTP) as a marker of bone resorption in patients with excessive secretion of parathyroid hormone (PTH). Our studies comprised of 15 patients with primary and 24 patients with secondary hyperparathydroidism. In all patients serum PTH, osteocalcin and ICTP were detected by radioimmunoassay; the correlations between PTH and osteocalcin as well as between PTH and ICTP were also performed. Serum PTH was elevated in both, primary and secondary hyperparathyroidism. In primary hyperparathyroidism serum osteocalcin was moderately or definitely elevated, similarly serum ICTP was high. Following surgical removal of a parathyroid adenoma, concomitantly with a drop in serum PTH there was a rapid normalization of serum osteocalcin and ICTP. Secondary hyperparathyroidism in uraemia was characterised by markedly elevated serum osteocalcin and ICTP which surpassed the concentration of these markers in primary hyperparathyroidism. There was a positive correlation between serum PTH and osteocalcin levels, and a lower correlation between PTH and ICTP. From our studies it is concluded that excessive secretion of PTH in primary and secondary hyperparathyroidism stimulates bone formation and to higher degree--bone resorption.