sweat test, a method for evaluating sodium and chloride excretion from the sweat glands, often the first test performed in the diagnosis of cystic fibrosis. The sweat glands are stimulated with a drug such as pilocarpine, and the perspiration produced is analyzed. The eccrine glands of patients with cystic fibrosis produce sodium and chloride concentrations that are three to six times normal. Chloride levels above 60 mEq/L and sodium levels above 90 mEq/L are considered diagnostic for the disease. The test is very reliable, and although it may be useful at any age, it is usually performed on infants from 2 weeks to 1 year of age. See also cystic fibrosis.
