Citrulline Quantitative Urine Test

The test measures the amount of citrulline in your urine.

The test is done for several reasons, such as:

• To diagnose certain metabolic disorders like citrullinemia.
• To monitor and evaluate the effectiveness of treatment for citrullinemia.
• To assess or evaluate patients with symptoms suggestive of a metabolic disorder or metabolic acidosis.
• To evaluate patients with an unexplained progressive neurological disorder.

Your doctor may recommend this test if you have:

• Symptoms such as lethargy, seizures, psychomotor retardation, neuropathy, and developmental delay, which are suggestive of metabolic acidosis or a metabolic disorder.
• A provisional diagnosis of citrullinemia based on clinical history and symptoms.
• A family history of inherited metabolic disorders.
• An indication to evaluate urea cycle disorders as part of newborn screening.

Elevated levels of citrulline in urine may indicate the presence of citrullinemia, while low levels may point to other urea cycle disorders or metabolic abnormalities. 

You will be given a special container to collect a spot urine sample, which is usually to be collected first thing in the morning. The sample should be kept refrigerated until it is brought to the laboratory for testing.

To prepare for this test, remember the following points:

• You may need to avoid certain medications or amino acid supplements before the test if directed by your doctor.
• Fasting is recommended but not mandatory.
• Drink plenty of fluids and follow any other instructions provided by your doctor.
• You might be asked to provide a detailed medical history and list of medications you are currently taking.

Other tests that may be ordered alongside this test include the following:

• Blood tests to check for levels of amino acids in the blood
• Liver function tests
• Genetic testing
• Imaging tests such as magnetic resonance imaging (MRI) or computed tomography (CT) scans

Citrulline urine test

Citrullinemia is a rare genetic disorder where the body cannot process ammonia and remove it from the body, leading to a buildup of toxic levels of ammonia in the bloodstream. It is often diagnosed in newborns during routine screening tests, but sometimes, symptoms may not appear until later in life. Symptoms of citrullinemia include seizures, developmental delay, vomiting, slowed growth, and coma.