Pediatric check-up

A 3 month old female born in a refugee camp in Europe is having her first pediatric check-up in the United States. She appears to be extremely small for her age and is classified as failure to thrive. Urinalysis from a specimen captured in a pediatric bag reveals trace positive proteins, trace positive ketones, and a strong mousy odor. A ferric chloride test was performed and a blue-green sustained color resulted. Since this baby was not born in a hospital, inborn error of metabolism screens were not previously performed but have since been ordered with results pending.

1. Given the results of urine test, what is a likely cause of the failure to thrive? Explain briefly referring to results provided.

2. How have the nitroso-naphtol test and silver nitrate tests in urine been using in screening for inborn errors of metabolism?