REDUCED BONE MASS AND FAT-FREE MASS IN WOMEN WITH MULTIPLE-SCLEROSIS - EFFECTS OF AMBULATORY STATUS AND GLUCOCORTICOID USE

Multiple sclerosis (MS) is associated with reduced bone mass and vitam in D deficiency. The underlying pathophysiology of the bone disease is uncertain, however, acute and long-term glucocorticoid use, progressi ve immobilization, vitamin D deficiency, and possibly skeletal muscle atrophy are likely to be determinants. The aims of this study were to determine (a) whether multiple sclerosis is associated with reduced fa t-free mass and (b) whether in patients with multiple sclerosis, ambul ation ability or glucocorticoid use is associated with bone mass and/o r fat-free mass. Seventy-one female patients with MS were compared wit h 71 healthy, age-matched female controls. Total body bone mineral con tent (TBBMC, kg), fat mass (FM, kg), and fat-free mass (FFM, kg) were measured using dual X-ray absorptiometry. Disability status was graded according to the Kurtzke Expanded Disability Status Scale (EDSS) as a mbulatory, with or without aide (EDSS score of 0 to 6.5), or predomina ntly wheelchair bound (EDSS score > 6.5). The patients with MS, when c ompared to age-comparable controls, had deficits in TBBMC (approximate to 8%, -0.3 +/- 0.1 SD, P < 0.04) and FFM (approximate to 5%, -0.3 +/ - 0.1 SE, P < 0.01). Both TBBMC and FFM were negatively associated wit h EDSS score (r = 0.33, P < 0.01, and r = 0.41, P < 0.01, respectively ). Patients with MS who were nonambulatory had even greater deficits i n TBBMC and FFM as compared with age-matched controls (-0.6 +/- 0.1 SD , P < 0.01, and -0.6 +/- 0.1 SD, P < 0.01, respectively). By contrast, as compared with age-comparable controls, ambulatory patients with MS had no deficits in bone mass or soft tissue mass. When compared with ambulatory patients with MS, nonambulatory patients with MS had defici ts in TBBMC and FFM (P < 0.01 and P < 0.01, respectively). The differe nce in TBBMC was largely caused by the difference in fat-free mass, wh ereas the difference in FFM was largely caused by the difference in gl ucocorticoid use based on analysis of covariance. We conclude that in patients with multiple sclerosis, physical disuse is the main determin ant for the reduction in bone mass, Glucocorticoid treatment is the ma jor determinant of the reduction in fat-free mass and thus also contri butes to the reduction in bone mass.