Chloride, Sweat

General

Synonym/Acronym:
Sweat test, pilocarpine iontophoresis sweat test, sweat chloride.

Rationale
To assist in diagnosing cystic fibrosis (CF).

Patient Preparation
There are no food, fluid, activity, or medication restrictions unless by medical direction.

Normal Findings
Method: Ion-specific electrode or titration.

Conventional and SI UnitsInterpretation
Birth–6 mo
0–29 mEq/L or mmol/LNormal
30–59 mEq/L or mmol/LBorderline
Greater than 60 mEq/L or mmol/LConsistent with the diagnosis of CF
6 mo–adult
0–39 mEq/L or mmol/LNormal
40–59 mEq/L or mmol/LBorderline
Greater than 60 mEq/L or mmol/LConsistent with the diagnosis of CF

Critical Findings and Potential Interventions
Greater than 60 mEq/L or mmol/L (SI greater than 60 mEq/L) is considered diagnostic of CF.

Timely notification to the requesting health-care provider (HCP) of any critical findings and related symptoms is a role expectation of the professional nurse. A listing of these findings varies among facilities.

Consideration may be given to verification of critical findings before action is taken. Policies vary among facilities and may include requesting recollection and retesting by the laboratory.

The validity of the test result is affected tremendously by proper specimen collection and handling. Before proceeding with appropriate patient education and counseling, it is important to perform duplicate testing on patients whose results are in the diagnostic or intermediate ranges. A negative test should be repeated if test results do not support the clinical picture.

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