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Histidine/Creatinine Ratio, Urine

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

A urine test that compares histidine with creatinine, helping evaluate elevated histidine levels and possible histidinemia.

Quick summary

["This test helps determine whether unusually high urinary histidine may indicate histidinemia."]

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

Key facts at a glance

LOINC
30047-5
Short code
Histidine/Creat Ur-Rto
Synonyms
Histidine/Creat Ur-Rto
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?

The urine histidine/creatinine ratio measures the amount of histidine relative to creatinine in a urine sample. Creatinine is used to help account for how concentrated the urine is.

Why might I need this test?

This test is often used to evaluate elevated histidine found during newborn screening or to investigate a family history of histidinemia. It may also be used to monitor treatment or dietary changes.

How is the test performed?

A urine sample is collected and analyzed in a laboratory to determine the histidine and creatinine amounts. The laboratory then calculates their ratio.

How do I prepare for the test?

Follow the collection instructions provided by your healthcare professional. The sample may need to be collected as a first-morning urine or over a specified period, and the amount of protein and histidine in the diet may need to be considered.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

An elevated ratio may indicate that the body is not breaking down histidine normally, which can occur with histidinemia, an inherited disorder of histidine metabolism. Interpretation depends on the person's age, symptoms, diet, urine collection method, and other laboratory findings, so an abnormal result should be confirmed by a healthcare professional.

Short name

Urine Histidine/Creatinine Ratio

Frequently asked questions

What is histidinemia?
Histidinemia is an inherited condition in which the enzyme needed to metabolize histidine does not work normally. It can cause elevated histidine in the blood and urine and may lead to eye, skin, or developmental problems if untreated.
Why is creatinine included in the result?
Urine can range from very dilute to highly concentrated. Comparing histidine with creatinine helps reduce the effect of urine concentration when interpreting the result.
Does an elevated result confirm histidinemia?
No. An elevated urine histidine/creatinine ratio suggests possible abnormal histidine metabolism but does not establish a diagnosis by itself. Genetic testing and other blood and urine tests may be needed.
  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