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Krebs von den Lungen-6 (KL-6)

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

KL-6 is a mucin-like glycoprotein that serves as a marker for the activity and severity of various lung diseases, particularly interstitial lung diseases.

Quick summary

KL-6 is a glycoprotein biomarker used to assess lung disease activity and severity.

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

Key facts at a glance

Units
U/mL
Clinical utility
diagnostic
Result kind
quantitative
FDA-cleared
Roche KL-6, Fujirebio KL-6, Seikagaku KL-6
interpretation: {"text":"KL-6 levels below 500 U/mL are considered within the normal range.","label":"Normal"}; {"text":"KL-6 levels above 500 U/mL may indicate active lung disease or lung damage.","label":"Elevated"}

KL-6 is a mucin-like glycoprotein that is primarily expressed on the surface of alveolar type II cells and bronchiolar epithelial cells in the lungs. Elevated levels of KL-6 in the blood are indicative of damage to these cells, which can occur in various lung diseases such as interstitial pneumonia, sarcoidosis, and pulmonary fibrosis.

The measurement of KL-6 is useful in diagnosing and monitoring the progression of interstitial lung diseases. It can also help in evaluating the effectiveness of treatment and predicting prognosis. Elevated KL-6 levels are associated with increased disease activity and poorer outcomes.

Normal KL-6 levels are typically below 500 U/mL. Levels above this threshold may suggest the presence of active lung disease. However, it is important to interpret KL-6 levels in conjunction with other clinical findings and diagnostic tests for a comprehensive evaluation.

Frequently asked questions

What does a high KL-6 level mean?
A high KL-6 level may indicate the presence of active lung disease, such as interstitial pneumonia or pulmonary fibrosis, and suggests the need for further evaluation.
Can KL-6 levels be used to monitor treatment effectiveness?
Yes, KL-6 levels can be monitored over time to assess the effectiveness of treatment and disease progression.
  1. 1
    KL-6 as a biomarker for interstitial lung diseasesSource
  2. 2
    Role of KL-6 in diagnosing and monitoring interstitial lung diseasesSource

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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

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Medically reviewed by WellAlly Editorial Team Last reviewed August 25, 2026. · Read our editorial policy