Osteogenesis imperfecta: Bone turnover, bone density, and ultrasound parameters

We studied 21 patients(ll men and 10 women) with osteogenesis imperfecta (O I) and 21 age- and sex-matched controls. In all patients we measured serum levels of total alkaline phosphatase (ALP), type I procollagen carboxy-term inal propeptide (PICP), osteocalcin (BGP), urinary excretion of hydroxyprol ine (HOP/Cr), and pyridinoline crosslinks (Pyr/Cr). Bone mineral density wa s measured at the distal radius (BMD-R) and at the lumbar spine (BMD-LS) by dual X-ray absorptiometry (DXA). Ultrasound parameters were also performed at the calcaneous with the Achilles device and at the phalanxes with DBM S onic 1200. A significant reduction (P < 0.001) in BMD and in ultrasound par ameters was found in OI patients compared with normals. PICP was significan tly reduced in the OI patients compared with controls (P < 0.001); other ma rkers of bone turnover were higher in OI than in controls, but the differen ce did not reach the statistical significance. A significant correlation (P < 0.05) was found between PICP and BMD at the lumbar spine and between PIC P and ultrasound parameters at the calcaneous. On the basis of our data, we conclude that patients with OI show low values of BMD and ultrasound param eters; therefore in these patients, not only is bone mass disturbed but als o bone quality. The reduced levels of PICP in OI patients confirm that most OI patients have defects in collagen I biosynthesis. These defects may con tribute to the fragility of OI bone by interfering with complete mineraliza tion and/or normal tissue structure. PICP may be considered a useful marker in the clinical management of OI.