Phenylalanine Quantitative Spot Urine Test

This test measures the amount of phenylalanine in your urine.

• To diagnose phenylketonuria (PKU), a rare genetic disorder that affects how your body processes phenylalanine
• To assess the effectiveness of PKU treatment
• To monitor phenylalanine levels if you have undergone liver or kidney transplantation

Your doctor might recommend this test if

• you or your child has symptoms suggestive of PKU, such as intellectual disability, seizures, behavioural problems or an unusual odour in urine or sweat
• you have a family history or genetic risk factors for PKU
• your child has a positive newborn screening result
• you or your child has a provisional diagnosis of PKU based on clinical history and other diagnostic tests

Elevated levels of phenylalanine in urine may indicate the presence of PKU or other conditions that affect phenylalanine metabolism.

Collect a 10 ml sample of urine in a special container. A fasting blood test may also be done alongside this test to confirm the diagnosis of PKU.

• If you or your child has been diagnosed with PKU, you should follow a special diet low in phenylalanine for a few days leading up to the test.
• Your doctor may also ask you to avoid certain medications that can interfere with your test results.
• Consult your doctor for any specific requirements.

• Blood phenylalanine levels: A blood test that measures the amount of phenylalanine in your blood
• Neonatal screening tests: A series of blood tests done on newborns to detect metabolic disorders, including PKU
• Genetic testing: Analysing DNA samples to determine if there are mutations in genes associated with PKU

PKU urine test or spot urine phenylalanine test

PKU is a rare genetic disorder that affects how your body processes phenylalanine, an essential amino acid. PKU is caused by a deficiency in the enzyme phenylalanine hydroxylase, which converts phenylalanine into another amino acid called tyrosine.