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Cystine in Serum or Plasma (Mass Concentration)

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

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.

Quick summary

["Understanding your cystine levels can help identify genetic conditions related to amino acid metabolism."]

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

Key facts at a glance

LOINC
13371-0
Short code
Cystine CSF-mCnc
Synonyms
Cystine CSF-mCnc
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why This Test Might Be Ordered

Your healthcare provider may recommend this test if you have symptoms like kidney stones, skin rashes, or a family history of genetic disorders affecting amino acid metabolism. It could also be part of a broader evaluation for conditions like cystinosis or other inherited metabolic diseases.

What to Expect Before the Test

No special preparation is usually needed, but you may be asked to fast for a few hours before the blood draw if your test involves fasting. Bring any medications or supplements you’re taking to your appointment.

How the Test Works

A small sample of blood is taken from a vein in your arm. The sample is then analyzed in a lab to measure cystine levels using a specialized technique, often high-performance liquid chromatography (HPLC).

What the Results Mean

Results are compared to a reference range for healthy individuals. High levels may suggest genetic disorders like cystinosis, while very low levels might indicate other metabolic issues or errors in amino acid processing.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

Cystine Level

Frequently asked questions

How long does it take to get my results?
Test results are typically available within 1 to 3 business days, depending on your lab’s processing time. Your healthcare provider will contact you once they have the results.
What causes cystine levels to be abnormal?
Abnormal cystine levels can result from genetic mutations (e.g., cystinosis), certain medications, or metabolic disorders. If you have a family history of amino acid-related disorders, this test may be part of genetic screening.
Can diet affect cystine levels?
Dietary changes alone rarely affect cystine levels measured in blood tests. However, if you’re managing a condition like cystinosis, your doctor may recommend a specialized diet to help reduce cystine buildup.
  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