Phenylketonuria is detected by which urine test:

Guthrie Test: It is a rapid screening test. Ceain strains of bacillus subtilis need phenylalanine as an essential growth factor. Bacteria cannot grow in a medium devoid of phenylalanine. Bacterial growth is propoional to the phenylalanine content in the patient's blood. Good to know: Ferric chloride Test: Phenyl ketones in urine can be detected by this test. A transient blue-green color is a positive test. Nitroprusside Test is used for the colour reaction of amino acid Sulfhydryl group (Cysteine.) Ref: Textbook of Biochemistry DM Vasudevan, 5th Ed Page 22, 206