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Serum Galactose Concentration (24-Hour Urine Collection)

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

This test measures how much galactose appears in your urine over 24 hours. It helps check for galactosemia, a rare genetic disorder that affects how your body processes galactose, a sugar found in milk and dairy products.

Quick summary

["This test helps diagnose galactosemia by detecting abnormal galactose levels in urine."]

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

Key facts at a glance

LOINC
93853-0
Short code
GALNS Ur-cCnc
Synonyms
GALNS Ur-cCnc
Category
chemistry
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

Why This Test Is Done

Your doctor may order this test if you have symptoms like vomiting, diarrhea, or poor weight gain in infants, or if you have a family history of galactosemia. It’s also used in newborn screening programs to catch the condition early.

What to Expect Before the Test

You’ll need to collect all urine for 24 hours, starting after midnight on one day and ending after midnight the next. Store the urine in a cool place and bring the entire sample to the lab. Avoid drinking extra fluids if instructed.

What to Expect During the Test

No special preparation is needed beyond the urine collection. The lab will analyze the sample to measure galactose levels.

What the Results Mean

High levels of galactose in urine suggest galactosemia. Low or normal levels may mean the disorder isn’t present, but further testing may still be needed.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Galactosemia is a metabolic disorder where the body can’t break down galactose properly. If untreated, it can cause liver damage, intellectual disabilities, or other serious health issues. Early diagnosis through urine testing allows for timely dietary changes (avoiding dairy) and medical management to prevent complications.

Short name

Galactose Urine Test

Frequently asked questions

What causes abnormal galactose levels in urine?
Abnormal levels are most commonly linked to galactosemia, a genetic disorder. Rarely, other metabolic or kidney conditions may cause temporary spikes, but this test is primarily for diagnosing galactosemia.
How is galactosemia treated?
Treatment involves avoiding galactose (found in dairy products) and sometimes medications to help metabolize it. Early diagnosis is key to preventing long-term health problems.
Can this test be done on blood instead of urine?
No, this test specifically measures galactose in urine over 24 hours. Blood tests can check for related enzymes, but not galactose excretion.
  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