Q99
Single choice
A deficiency of argininosuccinate synthetase (ASD) can be suspected in a 2448-hour-old neonate with elevated serum ammonia. To discriminate the fact that the hyperammonemia is indeed due to ASD and not due to a deficiency in other urea cycle enzymes, one can assay for the serum concentration of citrulline and urinary orotic acid concentration.
Which of the following would best describe the expected findings?