Serum levels of the pyridinoline crosslinked carboxyterminal telopeptide of type I collagen (ICTP) and osteocalcin in rachitic children in Nigeria

We measured the levels of the pyridinoline crosslinked carboxyterminal telopeptide of type I collagen (ICTP) and osteocalcin (OC) in the serum of 12 rachitic and 27 healthy Nigerian children, and compared the performance of these relatively new markers of bone metabolism with established laboratory parameters of skeletal disease. Active rickets was diagnosed on the basis of clinical and biochemical criteria. Serum calcium and phosphorus concentration and alkaline phosphatase activity were determined using clinically accepted methods. Radioimmunoassay was performed to quantify parathyroid hormone, 1-,25-dihydroxyvitamin D D, OC, and ICTP. The rachitic children had statistically significant serum elevations of ICTP and osteocalcin as compared with age- and sex-matched controls. Serum levels of ICTP correlated with alkaline phosphate activity. As a marker of abnormal bone metabolism, ICTP performs at least as well as alkaline phosphate. ICTP and OC are valuable additions to the growing repertoire of bone markers.