Energy expenditure, body composition, and prevalence of metabolic disorders in patients with Duchenne muscular dystrophy.

INTRODUCTION: Duchenne muscular dystrophy (DMD) is a severe muscular disease characterized by progressive loss of functional muscle mass followed by changes in body composition.

AIM: To describe body composition, resting energy expenditure (REE), and metabolic disorders in DMD patients followed-up at a tertiary care center. To analyze the association with type of steroid and ambulatory status, and to compare obese DMD patients with patients with multifactorial obesity.

POPULATION AND METHODS: A prospective, observational, cross-sectional study was conducted. Anthropometric measurements were taken, evaluating body composition with bioelectrical impedance analysis (BIA), REE with indirect calorimetry, and biochemical parameters in all DMD patients seen between June 2013 and April 2014.

RESULTS: 63 boys between 5.4 and 18.7years of age were evaluated. Diagnosis of obesity ranged from 28% measuring body mass indexZ-score (BMIZ-score) to 70% using percentage of fat mass (%FM). Patients who had lost gait had a significantly higher %FM than those in whom gait was preserved (72% vs 46%, p<0.05). Insulin resistance was present in 29% associated with BMI Z-score and waist circumference and 40% had dyslipidemia associated with %FM, both of which were steroid independent. In obese DMD patients REE was lower than predicted and also lower than controls, and persist when dividing the patients into ambulators and non-ambulators.

CONCLUSIONS: A high prevalence of obesity was observed. BMI-Z-score underestimates the degree of FM. No correlation was found between steroid type and body composition or metabolic disorders. No differences were found in REE between ambulators and non-ambulators. Obese DMD patients have a lower REE than controls.