Biomarkers, including ammonia, urea, glutamine and [13C]urea were measured before and after a 3-day trial of N-carbamylglutamate (NCG) 100 mg/kg/d or 2.2g/m2/d if ≥ 25kg.
On each study day, after an overnight fast, a baseline sample of heparinized blood was obtained. Then, at time 0, each subject received an enteral dose of [1-13C]sodium acetate, dissolved in water. Blood samples were subsequently obtained at 15, 30, 45, 60, 90, 120, 180, and 240 minutes. In subjects ≤ 5 years (subjects 3, 4 and 5), a shortened 120 min protocol was performed, and only samples at 15, 30, 60, and 120 minutes were collected. (From Heibel et al., Hum Mutat. 2011 Oct;32(10):1153-60)