Sweat Testing Quality Assurance

Physicians should be aware of the clinical spectrum of CF and appropriately order a sweat test on patients suspected 

To monitor the accuracy and precision of the analytical process, two levels of controls should be performed every day when patient samples are analyzed. One control should reflect the concentration of sweat chloride concentration in a non-CF patient and the other control should reflect the concentration of sweat chloride found in a CF patient. The controls should be performed in parallel with patient samples and the results should fall within a predetermined range before patient results can be reported. Both short- and long-term quality control should be monitored. 

An important part of a quality assurance plan includes the external validation of sweat analysis accuracy through participation in proficiency testing. The CAP offers a proficiency testing program consisting of six specimens per year. Participants receive feedback concerning their performance on these specimens relative to others in their peer group. 

The results of the sweat test must be interpreted in light of the patient s clinical presentation by a physician knowledgeable about CF. There are several conditions other than CF that are associated with elevations in sweat electrolytes (Box 27-1). These conditions usually are distinguishable from CF based on the patient s clinical presentation. 

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