Skip to content

Cystinuria Profile — Serum Homocysteine/Cystine and Total Urine Cystine with Creatinine

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

Measures cystine and related amino acids in blood and urine to help evaluate possible cystinuria and urinary stone risk.

Quick summary

["This profile checks for excess cystine in urine and related amino-acid abnormalities that can contribute to kidney stones."]

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

Key facts at a glance

LOINC
79649-0
Short code
Hycs-Cys diS/Creat Ur-sRto
Synonyms
Hycs-Cys diS/Creat Ur-sRto
Category
kidney
Sample
urine
Container
Sterile urine container
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
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

What is this test?

This profile measures cystine and other amino acids involved in cystine metabolism. Blood testing assesses related substances such as homocysteine, while urine testing measures total cystine and creatinine.

Why might I need this test?

It may be ordered when kidney stones contain cystine, stones recur at a young age, or there is a family history of cystinuria. It can also help assess treatment and dietary needs.

How is the test performed?

A blood sample and a urine sample are analyzed for cystine and related amino acids. Urine creatinine is also measured to help interpret how concentrated the urine sample is.

How do I prepare for the test?

Follow the laboratory's instructions for urine collection, including any specified collection period, start time, and fasting requirements. Tell the laboratory if you are pregnant, taking supplements, or following a cystine-restricted diet.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

High urinary cystine may indicate cystinuria, an inherited condition in which the kidneys excrete too much cystine. Elevated homocysteine or other amino-acid abnormalities may suggest related metabolic conditions. Urine creatinine helps determine whether a cystine concentration reflects a dilute or concentrated specimen.

Short name

Cystinuria profile

Frequently asked questions

What is cystinuria?
Cystinuria is an inherited disorder that causes the kidneys to release extra cystine into the urine. High cystine concentrations can lead to cystine kidney stones.
Why is urine creatinine included?
Creatinine is commonly used to show how concentrated a urine specimen is. This helps the laboratory interpret the cystine result, especially when urine volume or hydration varies.
Does an abnormal result confirm cystinuria?
An abnormal result can support cystinuria but may require repeat testing and clinical or genetic evaluation. Kidney stone analysis and family history may also be used to confirm the diagnosis.
  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