Sweat Test

Cystic Fibrosis Sweat Test

Results

A sweat test measures the amount of salt chemicals (sodium and chloride) in sweat. Generally, chloride (sweat chloride) is measured.

Results are usually available in 1 or 2 days. Normal results vary from lab to lab.

Sweat chloride

Normal:	Less than 40 millimoles per litre (mmol/L)
Borderline:	40–60 mmol/L
Abnormal:	More than 60 mmol/L

Many conditions can change sodium and chloride levels. Your health professional will discuss any significant abnormal results with you in relation to your symptoms and medical history.

The test results do not indicate how severe the cystic fibrosis is. The test only shows if a person could have the disease.

Abnormal (high) values

High values:

• Usually mean a person has cystic fibrosis. Some people with cystic fibrosis have borderline or even normal sweat chloride levels.
• May be caused by other conditions. However, the sweat test is not used to diagnose these conditions, which include:
  • Adrenal gland problems, such as adrenal insufficiency or Addison's disease.
  • Hypothyroidism.
  • Kidney failure.

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Author:	Debby Golonka, MPH Ralph Poore	Last Updated: August 20, 2007
Medical Review:	Michael J. Sexton, MD - Pediatrics Susanna McColley, MD - Pediatric Pulmonology Andrew Swan, MD, CCFP, FCFP - Family Medicine
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