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Histidine/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 to help evaluate histidine excretion.

Quick summary

["This test measures how much histidine is being lost in urine compared with creatinine."]

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

Key facts at a glance

LOINC
25927-5
Short code
Histidine/Creat 24h Ur-sRto
Synonyms
Histidine/Creat 24h 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 test measures histidine, an essential amino acid, relative to creatinine in a 24-hour urine collection. The ratio helps account for differences in urine concentration and body size when interpreting histidine excretion.

Why might I need this test?

A clinician may order this test to evaluate amino acid excretion, particularly when nutrition, metabolic symptoms, or a suspected inherited amino acid disorder is being assessed. It is usually interpreted with other laboratory and clinical findings.

How is the test performed?

You collect all urine for exactly 24 hours using the container provided by the laboratory. The laboratory measures histidine and creatinine in the collection and calculates their ratio.

How do I prepare for the test?

Follow the laboratory's collection instructions, including discarding the urine collected before the designated start time. Maintain your usual diet and fluid intake unless your clinician gives different instructions, and tell the laboratory about medicines or supplements you take.

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 measure for urine excretion. Comparing histidine with creatinine helps reduce the effect of urine concentration and differences in body size.
What happens if the 24-hour urine collection is incomplete?
An incomplete collection can make the results unreliable. Contact the laboratory or clinician if you miss a large portion of the collection or are unsure how to collect it correctly.
Does an abnormal result diagnose a metabolic disorder?
No. This result alone does not diagnose a disorder. Your clinician may need to repeat the test and consider blood amino acid testing, genetic testing, nutrition assessment, and other findings.
  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