The relationship between basal metabolic rate and femur bone mineral density in men with traumatic spinal cord injury

Objectives: To investigate the relationship between basal metabolic rate (BMR) and hip bone mineral density (BMD) in people with spinal cord injury (SCI) and to determine whether neurologic factors contribute to this relationship. Design: Cross-sectional study. Setting: Inpatient SCI unit in a rehabilitation hospital. Participants: Thirty men with chronic (time since injury, > 1y) traumatic SCI with an American Spinal Injury Association Impairment Scale grade A or B. Subjects' mean age was 32 years (range, 20-45y). Interventions: All participants were evaluated with neurologic examination to define the level and severity of injury. BMR was determined by indirect calorimetry, and BMD was determined by dual-energy x-ray absorptiometry (DXA). Patients were allocated to osteoporotic, osteopenic, and normal bone density groups according to World Health Organization criteria. DXA was used also to estimate lean- and fat-tissue mass (in kilograms) by standard methods. DXA measurements were performed on the same day as BMR analysis. Main Outcome Measures: DXA and indirect calorimetry. Results: BMR correlated significantly with BMD of the total femur, femur neck, trochanter, and shaft. However, there was no correlation between BMR and femur Ward's triangle. These correlations were stronger in patients with tetraplegia. There was a moderate correlation between BMR and lean tissue mass (r=.66, P <.001), although femur BMD values did not correlate with lean tissue mass in our study group (P >.05). Conclusions: BMR is closely associated with BMD in men with SCI.