UKMLA PLAB AMC USMLE Prometric MCQ

Question Number 0598

Question:
An 11 month baby boy has recurrent vomiting. He has a history of convulsions precipitated by ingestion of a very sweet fruit juice. On examination he is noted to be jaundiced, his liver is enlarged and he appears irritable. Laboratory findings reveal a prolonged clotting time, elevation of bilirubin levels and proximal tubular dysfunction. A reducing substance is found in the urine during a fainting episode. Which test would most helpful in reaching a diagnosis?

a) anti-cholinesterase antibody
b) HLA B27
c) Rheumatoid factor
d) Creatinine phosphokinase
e) aldolase activity