Serum concentrations of procollagen I C-terminal propeptide, osteocalcin and insulin-like growth factor-I in patients with non-lethal osteogenesis imperfecta.

Serum concentrations of procollagen I C-terminal propeptide (PICP) were studied in 74 patients with various forms of non-lethal osteogenesis imperfecta and 27 unaffected family members. Using the standard deviation (SD) score, PICP concentrations were found to be > or = -1 SD in 16%, between -1 and -2 SD in 26% and < or = -2 SD in 58% of the patients with osteogenesis imperfecta compared to healthy controls. PICP values were lowest in osteogenesis imperfecta type I (-2.4 +/- 0.4 SD, n = 37) followed by type III (-1.9 +/- 0.5 SD, n = 13) and type IV (-1.3 +/- 0.7 SD, n = 20). Four patients with osteogenesis imperfecta with an atypical clinical course had normal or even elevated levels which may indicate heterogeneity in the underlying primary defects. In osteogenesis imperfecta type I, PICP concentrations proved to be a helpful serum marker for pedigree screening. Osteocalcin was high in 25 of 28 patients with osteogenesis imperfecta in the first decade but only in 1 of 18 older patients. Insulin-like growth factor-I was within the normal range in 53 cases of osteogenesis imperfecta, decreased in 2 and elevated in 3 patients. We conclude that PICP concentration is a useful parameter in the clinical management of osteogenesis imperfecta, including the assessment of future therapeutic interventions.