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Serum or plasma concentration of **N-acetyl-beta-D-glucosaminidase (NAG)

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

This test measures the activity of an enzyme called N-acetyl-beta-D-glucosaminidase, which helps assess liver and biliary tract function by detecting elevated levels in certain conditions.

Quick summary

["Elevated NAG may signal liver or bile duct issues; normal results suggest healthy function in these areas."]

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

Key facts at a glance

LOINC
6506-0
Short code
N men sg W135 Ag CSF Ql IF
Synonyms
N men sg W135 Ag CSF Ql IF
Category
chemistry
Sample
csf
Container
Sterile tube
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
if
Specimen volume
1-2 mL
Stability
Immediate analysis required, Refrigerated: 1h
Hemolysis max
200
TAT
4–24 hours
Order
routine

Why Is This Test Done?

Your healthcare provider may order an N-acetyl-beta-D-glucosaminidase (NAG) test to investigate symptoms like jaundice (yellowing of skin/eyes), abdominal pain, unexplained fatigue, or liver-related concerns. It can also help monitor liver disease progression or response to treatment.

What to Expect Before the Test

No special preparation is needed. You may have a blood draw, where a small needle is used to collect serum or plasma. If you’re taking medications, let your provider know—some may affect results.

What the Results Mean

Results are typically reported as enzyme activity levels (units per liter or milliliters). Higher-than-normal levels may indicate liver inflammation, bile duct blockage, or other conditions affecting these organs.

Common Conditions Linked to NAG Levels

Elevated NAG is often seen in conditions like hepatitis, biliary tract obstructions, or certain metabolic disorders. However, it’s not always definitive—other tests may be needed for diagnosis.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

Clinical Significance: NAG in Diagnosis and Monitoring

Short name

NAG Level

Frequently asked questions

What causes elevated NAG levels?
Elevated NAG can result from liver diseases (e.g., hepatitis), bile duct issues (e.g., gallstones blocking flow), or certain medications. It may also appear in rare genetic disorders affecting enzyme production.
How often should I get this test?
Your provider will determine frequency based on your symptoms, medical history, or treatment plan. Regular monitoring may be needed if you have chronic liver conditions or take medications that affect liver function.
Can diet or lifestyle affect NAG results?
Dietary changes alone won’t alter NAG levels, but certain foods (e.g., fatty foods) or medications may influence liver function indirectly. Always follow your provider’s guidance for test timing.
  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