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Protocol - Sweat Chloride Test

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Description:

Quantitative pilocarpine iontophoresis is the procedure also known as the sweat chloride test. It involves stimulation of sweat, collection of sweat onto gauze or filter paper, measurement of the weight or volume of sweat collected, and analyses to determine the sweat chloride concentration.

Protocol:

The following description is a summary. See Clinical and Laboratory Standards Institute (CLSI) document C34-A2 for the full protocol. The test should be performed at a CFF accredited laboratory. In addition, the CFF has also provided testing guidelines (LeGrys et al., 2007) that should be followed.

  • Pilocarpine is applied to gauze or filter paper.
  • Electrodes are attached to the gauze or filter paper.
  • The electrodes are attached to the newborn’s lower arm or upper leg for about 5 minutes. Sweat collection should not occur longer than 30 minutes.
  • Collect a minimum of 75 mg of sweat.
  • Quantitatively analyze the sweat for chloride concentration by coulometric titration using a chloridometer, or using the Schales and Schales mercuric nitrate procedure or an automated analyzer that has been validated against the other methods.
  • It is recommended but not required that the test be repeated on the newborn.

Reference values

Sweat chloride concentrations < 40 mmol/L are negative; 40 to 60 mmol/L are borderline/intermediate; > 60 mmol/L are positive.

Protocol Name from Source:

This section will be completed when reviewed by an Expert Review Panel.

Availability:

Publicly available

Personnel and Training Required

Trained laboratory staff at a Cystic Fibrosis Foundation-accredited laboratory.

Equipment Needs

Iontophoresis equipment (battery powered)

Requirements
Requirement CategoryRequired
Major equipment Yes
Specialized training Yes
Specialized requirements for biospecimen collection No
Average time of greater than 15 minutes in an unaffected individual No
Mode of Administration

Bioassay

Life Stage:

Infant, Toddler, Child, Adolescent, Adult, Senior, Pregnancy

Participants:

Infants 48 hours old to adults

Specific Instructions:

The Cystic Fibrosis Foundation (CFF) accredits cystic fibrosis centers to perform sweat testing. The CFF strongly recommends that any laboratory that performs sweat testing be accredited by their organization.

The Rare Genetic Conditions Working Group indicates that normally this test is performed on infants and young children and may be less accurate when performed on adults. Also the Working Group acknowledges, sweat testing is exclusively performed in relation to cystic fibrosis.

Selection Rationale

The sweat chloride test is considered the gold standard for the diagnosis of cystic fibrosis.

Language

English

Standards
StandardNameIDSource
Common Data Elements (CDE) Sweat Chloride Test Concentration 4798295 CDE Browser
Process and Review

This section will be completed when reviewed by an Expert Review Panel.

Source

CLSI. Sweat Testing: Sample Collection and Quantitative Chloride Analysis; Approved Guideline-Third Edition. CLSI document C34-A3. Wayne, PA: Clinical and Laboratory Standards Institute; 2009.

LeGrys, V. A., Yankaskas, J. R., Quittell, L. M., Marshall, B. C., & Mogayzel, P. J., Jr. (2007). Diagnostic sweat testing: The Cystic Fibrosis Foundation guidelines. Journal of Pediatrics, 151(1), 85-89.

General References

Farrell, P. M., Rosenstein, B. J., White, T. B., Accurso, F. J., Castellani, C., Cutting, G. R., Durie, P. R., Legrys, V. A., Massie, J., Parad, R. B., Rock, M. J., & Campbell, P. W.; Cystic Fibrosis Foundation. (2008). Guidelines for diagnosis of cystic fibrosis in newborns through older adults: Cystic Fibrosis Foundation consensus report. Journal of Pediatrics, 153(2), S4-S14.

Mishra, A., Greaves, R., & Massie, J. (2005). The relevance of sweat testing for the diagnosis of cystic fibrosis in the genomic era. Clinical Biochemist Reviews, 26, 135-53.

Protocol ID:

221701

Variables:
Export Variables
Variable NameVariable IDVariable DescriptionVersiondbGaP Mapping
PX221701_SweatTest_Borderlien PX221701010000 Negative Sweat test - Cystic Fibrosis 4 N/A
PX221701_SweatTest_Negative PX221701020000 Borderline Sweat test - Cystic Fibrosis 4 N/A
PX221701_SweatTest_Positive PX221701030000 Positive Sweat test - Cystic Fibrosis 4 N/A
Research Domain Information
Measure Name:

Sweat Chloride Test

Release Date:

April 30, 2015

Definition

An assay to determine if a person has cystic fibrosis.

Purpose

The sweat chloride test is the gold standard test used to diagnose cystic fibrosis. It is recommended after a newborn screens positive for cystic fibrosis or when a patient of any age is suspected of having cystic fibrosis.

Keywords

Cystic fibrosis, sweat chloride, sweat test, Cystic Fibrosis Foundation, CFF, quantitative pilocarpine iontophoresis, newborn screening