Bone turnover markers in patients with osteogenesis imperfecta.

Osteogenesis imperfecta (OI) is a heterologous group of rare inherited bone disorders resulting from defect in collagen synthesis or function. In previous studies, bone turnover has been found either increased or low-normal. These contradictory results might result from the study population made of children with prior recent fractures. We measured serum total and bone alkaline phosphatase (total and bone AP) serum osteocalcin (sOC), serum type I collagen C-telopeptide breakdown products (sCTX), urinary free-deoxypyridinoline (ufDPD), and urinary cross-linked N-telopeptides of type I collagen (uNTX) in 39 male and 38 premenopausal patients with different types of OI aged between 18 and 51 years who had not experienced new clinical fracture during 12 months preceding the laboratory assessment. The study also includes a control group of 29 men and 26 women matched for age and gender. Most bone markers were 50-200% higher in patients than in controls. Only sCTX was comparable to that found in controls. From a sub-analysis of the data, a trend for higher bone resorption markers was observed for any OI type, but patients with OI type III and IV had significantly higher values in ufDPD and uNTX than patients with type I OI, and their sOC levels were not significantly higher than in controls. These results provide a strong rational for the use of anti-resorbing agent in OI.