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SWEAT CHLORIDE

Mnemonic

SWEAT CL

Synonym

Quantitative Sweat Chloride for Cystic Fibrosis (CF) - Gibson and Cooke Pilocarpine Iontophoresis (GC QPIT) - QPIT

Guidelines

Requires scheduled collection between 8:00-11:00 am, Monday-Friday. Call the Diagnostic Center at (503) 413-4618 or the Emanuel Chemistry Laboratory at (503) 413-4083 to schedule inpatient and outpatient tests. 

Allow up to 90 minutes for application and removal of Macroduct collection coils.

Specimen Collection Requirements

Patient Preparation

Asymptomatic patients with a positive newborn screen must be at least 2 weeks of age and weigh greater than 2 kg before testing can be performed. Symptomatic patients must be at least 48 hours old. There is no weight requirement for symptomatic patients.

Collect

Sweat, Macroduct collection coils are provided by the laboratory.

Preferred Volume

60.0 µL

Minimum Volume

15.0 µL

Rejection Criteria

Less than 15.0 µL of sweat collected in Macroduct coils

Stability

Chloride in sweat should be measured immediately after collection.

Testing Information

Performed

Mon - Fri

Reported

24 hours

Method

Iontophoresis/Coulometry

Reference Values

Reference Values

Sweat chloride reference ranges are age specific. The result must be interpreted with regard to the patient's age and clinical presentation.

For children less than or equal to 6 months old:

 REFERENCE RANGE INTERPRETATION 
 0-29 mmol/L  CF unlikely (Negative)
 30-59 mmol/L  Intermediate
 ≥60 mmol/L  Indicative of CF (Positive)
The test becomes positive between 3-5 weeks of age in most affected infants.

For patients greater than or equal to 7 months old:

 REFERENCE RANGE INTERPRETATION 
 0-39 mmol/L  CF unlikely (Negative)
 40-59 mmol/L  Intermediate
 ≥60 mmol/L  Indicative of CF (Positive)

The Clinical and Laboratory Standards Institute (CLSI) Sweat Testing guidelines recommends repeating all positive and borderline tests at a different time.

CPT Codes

89230 (X2) and 82438 (X2)

Last Updated: Thursday, January 5, 2017 03:41:39 AM


Client Services: 503-413-1234