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N-Acetyl-Beta-D-Glucosaminidase (NAG)

Published: July 27, 2026Updated: August 25, 2026

NAG is an enzyme found in proximal renal tubular cells, and its levels in urine indicate kidney injury or dysfunction.

Quick summary

NAG is a urinary biomarker used to diagnose kidney damage.

Medically reviewed by WellAlly Editorial TeamLast reviewed August 25, 2026Editorial policy

Key facts at a glance

Units
U/L
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche NAG, BioAssay NAG
interpretation: {"text":"0–11.5 U/L: No significant kidney damage detected.","label":"Normal"}; {"text":">11.5 U/L: Potential kidney injury or dysfunction, requiring further investigation.","label":"Elevated"}

N-Acetyl-Beta-D-Glucosaminidase (NAG) is a lysosomal enzyme found in high concentrations in the proximal tubular cells of the kidneys. Its presence in urine serves as a sensitive marker for kidney injury.

Elevated levels of NAG in urine can indicate acute kidney injury, chronic kidney disease, or other renal pathologies. It is particularly useful for detecting early-stage kidney damage.

The reference range for urinary NAG is typically between 0–11.5 U/L. Levels above this range may necessitate further diagnostic evaluation and monitoring.

Frequently asked questions

What causes elevated NAG levels?
Elevated NAG levels can be caused by acute kidney injury, chronic kidney disease, exposure to nephrotoxic substances, or other renal pathologies.
How is the NAG test performed?
The NAG test involves collecting a urine sample, which is then analyzed for NAG enzyme activity using standardized laboratory techniques.
  1. 1
    N-Acetyl-β-D-glucosaminidase (NAG) as a Biomarker of Acute Kidney InjurySource
  2. 2
    Urinary Biomarkers for Kidney DiseaseSource

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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 25, 2026. · Read our editorial policy