SERUM CONCENTRATIONS OF PROCOLLAGEN-I C-TERMINAL PROPEPTIDE, OSTEOCALCIN AND INSULIN-LIKE GROWTH FACTOR-I IN PATIENTS WITH NONLETHAL OSTEOGENESIS IMPERFECTA

Serum concentrations of procollagen I C-terminal propeptide (PICP) wer e studied in 74 patients with various forms of non-lethal osteogenesis imperfecta and 27 unaffected family members. Using the standard devia tion (SD) score, PICP concentrations were found to be greater-than-or- equal-to -1 SD in 16%, between - 1 and -2 SD in 26% and less-than-or-e qual-to -2 SD in 58% of the patients with osteogenesis imperfecta comp ared to healthy controls. PICP values were lowest in osteogenesis impe rfecta type IV ( - 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 pati ents with osteogenesis imperfecta with an atypical clinical course had normal or even elevated levels which may indicate heterogeneity in th e underlying primary defects. In osteogenesis imperfecta type I, PICP concentrations proved to be a helpful serum marker for pedigree screen ing. Ostcocalcin was high in 25 of 28 patients with osteogenesis imper fecta 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 osteog enesis imperfecta, decreased in 2 and elevated in 3 patients. We concl ude that PICP concentration is a useful parameter in the clinical mana gement of osteogenesis imperfecta, including the assessment of future therapeutic interventions.