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Chloride, Sweat

Sweat Chloride (Gibson Cooke)

Test Codes

EPIC: LAB5852

Department

Special Chemistry

Instructions

• Outpatient: Sweat Chloride testing must be scheduled through the Beaumont Appointment Center at 800-328-8542.
• Inpatient: Sweat Chloride testing must be ordered in EPIC. The Special Testing Laboratory must be notified at 248-551-8044 when the test has been ordered.
• The patient must be adequately hydrated for proper sweat collection.
• Sweat should not be collected from patients in oxygen tents or on infants less than 48 hours old.
  

Specimen Collection Criteria

Collect: Sweat specimen using the MacroDuct advanced method. (Minimum: 15µL or 0.015 g)

Rejection Criteria

Sweat specimen volume less than 15µL or weighing less than 0.015 g.

Specimens not collected and processed as indicated.

In-Lab Processing

Analyze specimen immediately.

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 4 hours
Refrigerated (2-8°C or 36-46°F): 72 hours
Frozen (-20°C/-4°F or below): Unacceptable

Specimen Storage in Department Prior to Disposal:

Specimens are discarded once analysis is complete.

Laboratory

Royal Oak Special Chemistry Laboratory

Performed

Wednesday.
Results available within one business day.

Reference Range

Interpretation	Result (mmol/L)	Comment
Normal	<30	CF unlikely.
Intermediate	30-59	Intermediate range – need further study to establish or rule out a CF diagnosis.
Possible CF	≥60	Indicative of CF for individuals presenting with a positive newborn screen, clinical features consistent with CF, or a positive family history.

Test Methodology

Coulometric Titration.

Interpretation

Sweat chloride values greater than 59 mmol/L are consistent with cystic fibrosis in an individual with clinical symptoms of the disease. Elevated values in an adult may not indicate the presence of cystic fibrosis but may reflect carrier status for a CF gene. Test results may be normal in CF individuals with salt depletion. Sweat chloride results may be increased in several other conditions with symptoms distinct from cystic fibrosis, including untreated adrenal insufficiency, familial hypoparathyroidism, nephrogenic diabetes insipidus, hypothyroidism, alcoholic pancreatitis, and some cases of renal disease.

Clinical Utility

This test aids in the diagnosis of cystic fibrosis.

CPT Codes

89230
LOINC: 2077-6

Contacts

Last Updated

4/14/2023