Description
Why It’s Done
This test is performed to:
• Diagnose cystinuria, especially in individuals with:
o Recurrent kidney stones or urinary tract blockages.
o Painful urination or signs of hematuria (blood in the urine).
• Monitor patients with known cystinuria for excessive cystine levels.
• Investigate unexplained kidney stones or symptoms of renal dysfunction in children or adults.
• Provide important genetic information for family planning as cystinuria is inherited in an autosomal recessive manner.
Preparation
• A 24-hour urine collection may be required, during which all urine produced over a 24-hour period is collected in a special container.
o If using a random urine sample, ensure the sample is collected midstream.
• Hydrate well prior to collection, as dehydration may influence the concentration of cystine.
• Avoid intense physical activity before the test as it may affect the results.
• Inform the doctor of any medications or supplements being taken, as some drugs can affect cystine excretion.
