Sweat Test

Cystic Fibrosis Sweat Test, Iontophoresis Test (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 in people age 6 months and older

Normal:	Less than 40 millimoles per liter (mmol/L)
Borderline:	40–59 mmol/L
Abnormal:	60 mmol/L or more

Sweat chloride in babies younger than 6 months

Normal:	Less than 30 mmol/L
Borderline:	30-59 mmol/L
Abnormal:	60 mmol/L or more

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. But 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	Last Updated: June 23, 2009
Medical Review:	Michael J. Sexton, MD - Pediatrics Susanna McColley, MD - Pediatric Pulmonology
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