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Homogentisic Acid/Creatinine Ratio, Urine

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

A urine test that measures homogentisic acid relative to creatinine, helping evaluate and monitor conditions that cause increased homogentisic acid in the urine.

Quick summary

["This test measures urinary homogentisic acid adjusted for urine concentration and is commonly used to evaluate alkaptonuria."]

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

Key facts at a glance

LOINC
47650-7
Short code
Homogentisate/Creat Ur-sRto
Synonyms
Homogentisate/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 test measures homogentisic acid in urine relative to the amount of creatinine in the same sample. Creatinine is used as a reference to account for differences in urine concentration.

Why might I need this test?

It may be used to help diagnose alkaptonuria, an inherited condition in which the body does not fully break down homogentisic acid. It can also be used to monitor treatment or disease progression.

How is the test performed?

A urine sample is collected and analyzed in the laboratory. The laboratory measures homogentisic acid and creatinine and calculates their ratio.

How do I prepare for the test?

No special preparation is usually required unless your clinician requests a timed collection. Follow the laboratory's instructions and tell the care team about any medicines or supplements you are taking.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

An elevated homogentisic acid-to-creatinine ratio may indicate increased urinary excretion of homogentisic acid, as can occur with alkaptonuria. The result may also be influenced by kidney function, urine concentration, diet, and certain medicines, so it should be interpreted alongside the other laboratory findings.

Short name

Urine homogentisic acid ratio

Frequently asked questions

What is homogentisic acid?
Homogentisic acid is a substance produced during the breakdown of aromatic amino acids. In alkaptonuria, it accumulates in the body and is released in urine.
Why is creatinine included in the result?
Creatinine helps account for how concentrated or dilute the urine sample is. This makes the homogentisic acid measurement more useful for comparison between samples.
Does an elevated result confirm alkaptonuria?
An elevated result can support suspicion for alkaptonuria but may not confirm it by itself. Your clinician will consider symptoms, other tests, and sometimes genetic testing.
  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