Skip to content

Cystine in Urine (Quantitative)

Published: August 9, 2026Updated: August 16, 2026

This test measures the amount of cystine, a type of amino acid, in your urine. It helps identify conditions where cystine builds up abnormally, which can affect kidney function.

Quick summary

["Assessing kidney health and potential genetic disorders linked to cystine accumulation."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
45387-8
Short code
Cystine Cry #/area UrnS LPF
Synonyms
Cystine Cry #/area UrnS LPF
Category
chemistry
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
microscopy-light-lpf
Specimen volume
10 mL
Stability
Room temperature: 2h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
0
Lipemia max
0
Icterus max
0
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your doctor may recommend this test if you have symptoms like kidney stones, recurrent kidney infections, or if you have a family history of conditions like cystinuria, which causes cystine crystals to form in the kidneys and urinary tract.

What to Expect Before the Test

No special preparation is needed. You’ll provide a urine sample, typically collected in the morning. Avoid excessive fluid intake before the test to ensure accurate results, as it may dilute the sample.

How the Test Works

The urine sample is analyzed using a specialized method to measure cystine levels. This helps determine if cystine is present in amounts that could indicate a medical condition.

Possible Results and Next Steps

If your results are within normal ranges, your doctor may still monitor you for symptoms or repeat the test if needed. Elevated levels may prompt further testing or a referral to a specialist for additional evaluation, such as genetic counseling or kidney function assessments.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

High levels of cystine in urine can signal cystinuria, a genetic disorder causing cystine crystals to form in the kidneys and urinary tract, leading to kidney stones, infections, or chronic kidney damage. Early detection can help manage symptoms and prevent complications.

Short name

Urine Cystine Level

Frequently asked questions

What causes cystine to build up in urine?
Cystine buildup in urine is most commonly linked to cystinuria, a genetic disorder that affects how your body absorbs certain amino acids, including cystine. Other rare conditions or kidney dysfunction may also contribute.
How is cystine in urine tested?
The test measures cystine concentration in your urine using a laboratory method that detects the presence and amount of cystine crystals or amino acids. This is typically done through a urine sample collected in the morning.
Can diet affect cystine levels in urine?
Dietary changes alone won’t alter cystine levels in urine for people with cystinuria, as the condition is genetic. However, maintaining proper hydration and working with a doctor to manage symptoms is important.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy