Cystine in Serum or Plasma (Mass Concentration)
This test measures the amount of cystine, an amino acid, in your blood. Cystine is important for protein synthesis and maintaining healthy skin, hair, and nails.
["Understanding your cystine levels can help identify genetic conditions affecting protein metabolism."]
Key facts at a glance
- LOINC
- 13394-2
- Short code
- Cystine Amn-mCnc
- Synonyms
- Cystine Amn-mCnc
- Category
- chemistry
- Sample
- fluid
- Container
- Sterile tube
- Units
- N/A
- Fasting
- false
- Population
- adult
- Sex
- all
- Age range
- 18–65 years
- Specimen volume
- 2-5 mL
- Stability
- Room temperature: 2h, Refrigerated: 24h
- Hemolysis max
- 300
- TAT
- 4–24 hours
- Order
- routine
Why This Test Might Be Ordered
Your healthcare provider may recommend this test if you have symptoms like joint pain, skin rashes, or a family history of conditions like cystinosis, a rare genetic disorder that causes cystine crystals to build up in organs. It may also be part of screening for other metabolic disorders.
What to Expect Before the Test
No special preparation is usually needed, but you may be asked to fast for 8–12 hours before the test if it involves drawing blood. If you’re taking blood from a vein, you might feel a slight pinch, but it’s generally quick and painless.
What the Test Involves
A healthcare professional will collect a blood sample from a vein in your arm using a small needle. The blood is then sent to a lab for analysis. The test measures cystine concentration in your serum or plasma.
What the Results Mean
Results are compared to standard reference ranges for cystine levels in blood. Abnormally high levels may suggest conditions like cystinosis, while very low levels could indicate other metabolic or genetic issues. Your provider will discuss these findings with you.
Clinical interpretation
How abnormal results are interpreted and what conditions they suggest.
Elevated cystine levels are most commonly associated with cystinosis, a progressive genetic disorder that affects multiple organs, particularly the kidneys and eyes. Early detection through blood testing can help manage symptoms and slow disease progression. Low levels may warrant further investigation into other metabolic or genetic conditions.
Short name
Cystine Level
Frequently asked questions
What causes cystine levels to be tested?
How long does it take to get results?
Can diet or medications affect cystine levels?
Sources
- 1
- 2Lab Tests OnlineSource
- 3
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.
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