Resting Energy Expenditure and Substrate Oxidation in Malnourished Patients With Type 1 Glycogenosis

Context: Type 1a and 1b glycogenosis [glycogen storage disorder (GSD)1a, GSD1b] are rare diseases generally associated with malnutrition. Although abnormal substrate oxidation rates and elevated energy expenditures might contribute to malnutrition, this issue has not been investigated. Objective: To investigate whether abnormal resting energy expenditure (REE) 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 Patients: Five consecutive patients with GSD1 (4 type a, 1 type b; 3 men, 2 women; age range, 19 to 49 years) Main Outcome Measures: The usual clinical procedures for patients with malnutrition, including REE and basal substrate oxidation rate (both indirect calorimetry), body composition (bioimpedance method), muscle strength (hand-grip test), and the usual laboratory tests, were performed. Results: Malnutrition was clearly diagnosed in 2 patients (1 GSD1a and 1 GSD1b), with REE elevated in all five patients, and especially, in the two malnourished patients (+124% and +32.1% vs predictive values using Harris-Benedict equations). The two malnourished patients also exhibited lower basal protein oxidation rates (7.7% and 6.6%) than the nourished patients (range, 12.1% to 24.7%), with higher carbohydrate or lipid oxidation rates. Additionally, the two malnourished patients exhibited higher blood concentrations of lactic acid than the nourished patients. Conclusions: According to data obtained from our small sample of patients with GSD1, elevated REEs seem to be a common characteristic that might contribute to malnutrition. Low basal protein oxidation rates and elevated blood lactic acid concentrations appear to be associated with malnutrition.