Sweat Chloride

Test Code

SWCLT

Alias/See Also

Cystic Fibrosis testing

Minimum Volume

15 ul sweat

Methodology
Chloridometer

Setup Schedule

M-F 8 am-6 pm

Reference Range

SWCLC: Sweat Collection Site: (Right arm, left arm, right leg, left leg)
SWCLV: Sweat Volume: Minimum of 15 ul for valid testing
SWCL: Sweat Chloride result: 0-30 mmol/L

AGE

NORMAL RANGE

(CF unlikely)

INTERMEDIATE RANGE

(possible CF, additional testing recommended)

Abnormal*

Infants to Adults

CL < 29 mmol/L

Cl 30-59 mmol/L

Cl > 60 mmol/L

Clinical Significance

The quantitative measurement of the chloride in sweat (commonly called the "Sweat test") is an important part of the diagnostic algorithm for cystic fibrosis. With an approximate incidence of 1:3200 in Western Europe and the USA, CF is the most common life-threatening genetic disease within the Caucasian population.

It is an autosomal recessive disorder characterized by viscous secretions that affect the exocrine glands, primarily in the lungs and pancreas. Patients with CF have an increased concentration of sodium, chloride, and potassium in their sweat.

The criteria for the diagnosis of CF include the presence of one or more characteristic phenotypic features;

a history of CF in a sibling,
or a positive newborn screening result;
an increased sweat chloride concentration by pilocarpine inotophoresis on two or more occasions,
or identification of two CF-causing mutations or demonstration of abnormal nasal ion transport.

Positive and intermediate range of results are typically followed by DNA testing. Repeat Sweat Chloride may be indicated in confirmed CF patients who do not follow the expected clinical course.

Performing Laboratory
CRMC Laboratory

Additional Information
Collection SOP
OP Scheduled Test Requisition

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.