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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 amount of N-acetyl-beta-D-glucosaminidase, an enzyme found in certain cells of the liver, kidneys, and bile ducts. It helps assess potential damage to these organs.

Quick summary

["NAG can indicate liver or bile duct issues; higher levels may signal inflammation or injury."]

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

Key facts at a glance

LOINC
23929-3
Short code
ENA RNP IgG Ser Ql
Synonyms
ENA RNP IgG Ser Ql
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
CPT
82784
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

What Is N-acetyl-beta-D-glucosaminidase (NAG) Used For?

NAG is primarily used to evaluate liver function, particularly in diagnosing conditions like hepatitis, biliary obstruction, or cirrhosis. It may also help monitor progression or response to treatment in these cases. However, it’s not as commonly used as other liver tests like ALT or bilirubin.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate serum or plasma, where the enzyme levels are measured using a specialized lab technique.

When Might You Need This Test?

Your doctor may order an NAG test if you have symptoms like jaundice (yellowing of skin/eyes), abdominal pain, fatigue, or if you have known liver disease. It’s sometimes included in broader liver function panels.

What Are Common Causes of Abnormal Results?

Elevated NAG levels can occur due to liver inflammation (hepatitis), bile duct blockage (cholestasis), or certain medications. Lower levels may indicate normal function or, rarely, certain genetic conditions.

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

Why might my doctor check my NAG level?
Your doctor may check NAG levels to investigate unexplained liver concerns, monitor chronic liver diseases, or assess complications like bile duct stones or severe infections.
Can NAG levels alone diagnose liver disease?
No, NAG is one of many tests used together with clinical findings, imaging, and other lab results. It’s most helpful when combined with other markers like ALT, bilirubin, or ultrasound.
What do my NAG results mean if they’re high?
High NAG levels suggest possible liver or bile duct damage, but they don’t always indicate a specific cause. Your doctor will review your symptoms, medical history, and other tests to determine next steps.
  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