Collagen peptides in osteogenesis imperfecta, idiopathic juvenile osteoporosis and Ehlers--Danlos syndrome.

We evaluated the potential of the carboxy-terminal propeptide of type I procollagen (PICP), the carboxy-terminal telopeptide of collagen I (ICTP), and the amino-terminal propeptide of type III procollagen (PIIINP) to differentiate osteogenesis imperfecta (OI) from Ehlers-Danlos syndrome (EDS) and idiopathic juvenile osteoporosis (IJO) in paediatric patients. Markedly decreased serum concentrations of PICP were found in type I OI, while in IJO they were much less diminished, and in EDS they were near to normal. In type III and IV OI, the serum PICP level was lowered in prepubertal patients, whereas at puberty it was comparable to that in controls. Serum ICTP and PIIINP levels in patients with OI did not differ significantly from the levels in EDS and IJO. Measurements of serum PICP levels seem to be useful in discriminating OI from EDS and IJO in prepubertal children. In pubertal children, however, they lose their diagnostic power.