HOME
Return to Table of Contents
192 EVALUATION OF DENSITOMETRIC BONE-MUSCLE RELATIONSHIPS IN CROHN'S DISEASE (CD) M Mauro, D Armstrong
Intestinal Disease Research Program and Division of Gastroenterology, McMaster University, Hamilton, Ontario
BACKGROUND: Patients with CD are 1.4 to 2.5 times more likely than the normal population to sustain a fracture but the factors involved in the pathogenesis are not clearly understood. Osteopenia and osteoporosis are traditionally defined by bone mineral density (BMD) parameters, but this approach disregards the influence of bone size, a main determinant of bone strength. Bone mineral content (BMC) may, therefore, provide a better measure of bone strength. Bone mass is affected both by nutrition and by muscular activity. We hypothesized that BMC would correlate better than BMD with lean mass (LM - a measure of muscular mass) and that LM would correlate better than fat mass (FM) with BMC).
AIM: To assess the relationships between BMC, BMD, LM, and FM, determined by whole body densitometry in CD patients, using LM and FM as markers of exercise and caloric intake status, respectively.
METHODS: A retrospective chart review was performed to select CD patients who had a whole body densitometric (hologic) evaluation between 2003 and 2005. Densitometric determinations included the BMC, bone area (BA), BMD, LM and FM of the whole body and lower and upper limbs. Standard t tests, simple and multiple stepwise correlations were analyzed as required.
RESULTS: Data from 38 patients (38+/-15.1 years, M=15) were analyzed. Significant correlations were observed between whole body and regional BMC measurements with BA (r>0.86), LM (r>0.77) and body weight (r>0.55). In multiple regression analysis, LM was the most significant independant factor correlated with BMC in whole body and in all regions. There was no correlation between FM and BMC. LM (muscle mass) correlated significantly with BMC (bone mass) (r>0.77 in all regions) and BA (bone size) (r>0.72 in all regions). In contrast, the observed correlations between LM and BMD were relatively poor (r<0.5 in all regions).
SUMMARY: These findings support the hypothesis that BMC correlates better than BMD with LM and that there is a relatively poor correlation between bone mass and FM.
CONCLUSIONS: These results support the use of BMC in preference to BMD as a marker of bone strength and they suggest that muscular mass and activity, rather than overall body weight, are important determinants of bone strength in Crohn's disease. Thus, the management of bone loss in inflammatory bowel disease should address the effects of both nutrition and exercise on muscle mass.