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Test Code SWET-CL Sweat Chloride

Important Note

For internal ordering only. Not available to outreach clients.

Useful For

Analysis of sweat for chloride is a reliable test to aid in the diagnosis of Cystic Fibrosis in conjunction with the presence of chronic obstructive respiratory disease and/or intestinal malabsorption.  This test generally becomes positive in affected infants between 3-5 weeks of age.   Test is not recommended on infants less than 48 hours old.

Synonyms/Keywords

Iontophoresis, CF Sweat Test

Specimen Requirements

Fasting Required Specimen Type Preferred Container/Tube Acceptable Container/Tube Specimen Volume Specimen Minimum Volume
(allows for 1 repeat)		 Pediatric Minimum Volume
(no repeat)
No Sweat See Special Chemistry   Minimum acceptable sweat volume is 30 mg each arm Minimum acceptable sweat volume is 30 mg each arm Minimum acceptable sweat volume is 15 mg each arm

Collection/Processing Instructions

Call Genetics (ext. 17400) to schedule the test.  Special Chemistry personnel will collect the sweat specimen. 

Specimen Stability Information

Specimen Type Temperature Time
Sweat Refrigerated Up to 72 Hours

Rejection Criteria

If less than 15 mg sweat is obtained, the ordering physician will be notified for rescheduling of the test.

Reference Range Information

Performing Location Reference Range
Marshfield

For individuals of all ages:

 

29 mmol/L:  CF unlikely

 

30-59 mmol/L:  intermediate

 

60 mmol/L:  indicative of CF

 

Note: Sweat chloride values less than 30 mmol/L have been documented in genetically proven CF patients. Clinical correlation is necessary.

Marshfield Labs Performing Department

Marshfield Labs Special Chemistry

Performing Information

Performing Location Day(s) Test Performed Analytical Time Methodology/Instrumentation
Marshfield Monday through Friday, started before 1400 hours 1-2 hours Iontophoresis stimulation, Chloride titration with ChloroCheck Chloridometer

CPT Codes

CPT Modifier
(if needed)		 Quantity Description Comments
82438       Chloride, other source
89230       Collection

Outreach CPT Codes

CPT Modifier
(if needed)		 Quantity Description Comments
82438       Chloride, other source
89230       Collection

Ordering Applications

Ordering Application Description
COM Sweat Chloride
Cerner Sweat Chloride (MFLD ONLY)