title: Soft tissue body composition differences in monozygotic twins discordant for spinal cord injury.
abstract: To determine the effect of paralysis on body composition, eight pairs of male monozygotic twins, one twin in each pair with paraplegia, were studied by dual-energy X-ray absorptiometry. Significant loss of total body lean tissue mass was found in the paralyzed twins compared with their able-bodied co-twins: 47.5 +/- 6. 7 vs. 60.1 +/- 7.8 (SD) kg (P < 0.005). Regionally, arm lean tissue mass was not different between the twin pairs, whereas trunk and leg lean tissue masses were significantly lower in the paralyzed twins: -3.0 +/- 3.3 kg (P < 0.05) and -10.1 +/- 4.0 kg (P < 0.0005), respectively. Bone mineral content of the total body and legs was significantly related to lean tissue mass in the able-bodied twins (R = 0.88 and 0.98, respectively) but not in the paralyzed twins. However, the intrapair difference scores for bone and lean tissue mass were significantly related (R = 0.80 and 0.81, respectively). The paralyzed twins had significantly more total body fat mass and percent fat per unit body mass index than the able-bodied twins: 4.8 kg (P < 0.05) and 7 +/- 2% (P < 0.01). In the paralyzed twins, total body lean tissue was significantly lost (mostly from the trunk and legs), independent of age, at a rate of 3.9 +/- 0.2 kg per 5-yr period of paralysis (R = 0.87, P < 0.005). Extreme disuse from paralysis appears to contribute to a parallel loss of bone with loss of lean tissue in the legs. The continuous lean tissue loss may represent a form of sarcopenia that is progressive and accelerated compared with that in ambulatory individuals.
authors.affiliation: The Spinal Cord Damage Research Center, Mount Sinai Medical Center, Bronx, NY 10029, USA. AmSpungen@worldnet.att.net
authors.forename: A M
authors.initials: AM
authors.lastname: Spungen
authors.forename: J
authors.initials: J
authors.lastname: Wang
authors.forename: R N
authors.initials: RN
authors.lastname: Pierson
authors.forename: W A
authors.initials: WA
authors.lastname: Bauman
mesh_terms: D000328:Adult; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D004200:Diseases in Twins; D006801:Humans; D008297:Male; D008875:Middle Aged; D010264:Paraplegia / Q000209:etiology / Q000503:physiopathology*; D012044:Regression Analysis; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013997:Time Factors; D014430:Twins, Monozygotic