Resting energy expenditure and substrate oxidation in malnourished patients with type 1 glycogenosis

Context. Type 1a and 1b glycogenosis (GSD1a, GSD1b) are rare diseases generally associated with malnutrition. Although abnormal substrate oxidation rates and/or elevated energy expenditures might contribute to malnutrition, this issue has not been investigated. Objective. To investigate whether abnormal resting energy expenditure and substrate oxidation rate characterize patients with GSD1. Design. Cross-sectional study. Setting. Outpatient referral center for rare diseases and laboratory of clinical nutrition at the university hospital of Palermo (Italy). Patients. Five consecutive patients with GSD1 (4 type a, 1 type b), 3 males/2 females, age range 19-49 years. Main Outcome Measures. In the context of usual clinical procedures for patients with malnutrition, resting energy expenditure (REE, indirect calorimetry), basal substrate oxidation rate (indirect calorimetry), body composition (bioimpedance method), muscle strength (hand-grip test) and usual laboratory tests were performed. Results. Malnutrition was clearly diagnosed in 2 patients (1 GSD1a and 1 GSD1b), and REE was elevated in all 5 patients but in particular in the 2 malnourished patients (+124% and +32.1% versus predictive values according to Harris-Benedict equations). The 2 malnourished patients also exhibited lower basal protein oxidation rates (7.7% and 6.6%) than the non-malnourished patients (range: 12.1-24.7%), with higher carbohydrate or lipid oxidation rates. Additionally, the 2 patients with malnutrition exhibited higher blood concentrations of lactic acid than the non-malnourished patients. Conclusions. According to data obtained in this small sample of patients with GSD1, an elevated REE seems to be a common characteristic that may contribute to malnutrition. A low basal protein oxidation rate and elevated blood lactic acid concentrations appear to be associated with malnutrition. Type 1 glycogenosis are rare diseases associated with malnutrition. The measured resting energy expenditure was elevated in 5 patients and contributed to explain the occurrence of malnutrition. .