INCREASED DEGRADATION OF TYPE-I COLLAGEN IN PATIENTS WITH INFLAMMATORY BOWEL-DISEASE

To assess the mechanisms of osteopenia in inflammatory bowel disease ( IBD), the serum markers of bone formation (osteocalcin and carboxyterm inal propeptide of type I procollagen (PICP)) and bone degradation (ca rboxyterminal telopeptide of type I collagen (ICTP)), the bone mineral density (BMD) of the lumbar spine and the proximal femur and calcium intake of 150 unselected IBD patients and 73 healthy controls were inv estigated. The patients had higher ICTP values (3.69 (SD 1.40) mu g/l) than the healthy controls (3.25 (1.00) mu g/l, p=0.035), but no diffe rences in serum PICP and osteocalcin between these groups were detecte d. In the patients, the ICTP, PICP, and osteocalcin values did not hav e any significant correlation with BMD, but the patients with ICTP val ues above 3.6 mu g/l had significantly lower Z scores than those with lower ICTP. In the controls, however, a positive correlation between s erum ICTP and BMD was found. The ulcerative colitis patients with tota l colitis had higher values of ICTP (3.96 (1.58) mu g/l) than those wi th a left sided disease (3.04 (0.86) mu g/l, p=0.009). The patients wi th a history of clinically active disease (n=20) had higher ICTP (4.58 (1.55) mu g/l) and osteocalcin (12.56 (5.64) mu g/l) values than the patients (n=130) with quiescent disease (ICTP 3.56 (1.33), p=0.002, an d osteocalcin 9.76 (3.62), p=0.017). Increased serum osteocalcin, PICP , and ICTP concentrations and reduced EMD Z scores were found in a sub group of Crohn's disease patients with a history of an active disease (n=11). Raised serum ICTP and normal values of osteocalcin and PICP in IBD patients show increased breakdown of type I collagen without a co mpensatory increase in its synthesis suggesting an increased rate of b one degradation as a probable mechanism for osteopenia in IBD. Raised ICTP values are related to reduced bone mineral densities.