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Histidine-to-Creatinine Ratio, 24-Hour Urine

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

Measures the amount of histidine relative to creatinine in urine collected over 24 hours. This ratio can help evaluate how much histidine the body is excreting.

Quick summary

["This 24-hour urine test measures histidine excretion relative to creatinine to help evaluate amino acid metabolism."]

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

Key facts at a glance

LOINC
44372-1
Short code
Histidine/Creat 24h Ur
Synonyms
Histidine/Creat 24h Ur
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 test measures histidine, an amino acid, in all urine collected over a 24-hour period. The result is compared with the urine creatinine level, which helps account for differences in urine concentration and provides a ratio of histidine to creatinine.

Why might I need this test?

The test may be used to evaluate suspected disorders of amino acid metabolism, especially when there is concern about increased urinary histidine loss. It may also be used to monitor treatment or dietary management ordered by a specialist.

How is the test performed?

You collect all urine for exactly 24 hours, usually starting after emptying your bladder and ending with the final collection at the same time the following day. The laboratory measures histidine and creatinine and calculates their ratio.

How do I prepare for the test?

Follow any instructions provided by your clinician, including whether to maintain your usual diet or avoid certain protein foods. Keep the container refrigerated if directed, record each collection, and bring the full 24-hour sample to the laboratory promptly.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

24-hour urine histidine/creatinine ratio

Frequently asked questions

Why is creatinine included in this test?
Creatinine is used as a reference marker for urine concentration. Comparing histidine with creatinine helps reduce the effect of variations in how concentrated or dilute a 24-hour urine sample may be.
How is a 24-hour urine collection completed?
Collect every urine sample during the full 24-hour period without missing a collection. The first morning collection may be discarded, while the final collection is included, according to the specific instructions provided by the laboratory or clinician.
Can diet or medication affect the result?
Dietary protein and medications may influence amino acid excretion. Tell your clinician about major dietary changes, supplements, and medicines, and do not stop prescribed treatment unless instructed to do so.
  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