SALT EXCRETION IN SWEAT IN CYSTIC FIBROSIS.

Abstract

To the Editor: —Since the discovery of abnormally high levels of sodium and chloride in sweat in children with cystic fibrosis of the pancreas ( CFP) by di Sant'Agnese et al in 1953, the sweat test has proved to be a valuable help in pediatrics. The finding of a high salt excretion by eccrine sweat glands in a child with steatorrhea associated with pulmonary disease makes the diagnosis of CFP certain. Most investigators give the upper normal limit of sodium at 70-80 mEq/liter and that of chloride at 50-60 mEq/liter. In CFP very high sodium values up to 120 mEq/liter and more are encountered, and chloride levels may be even higher. Salt loss by sweating is also important in adrenal cortical hypofunction (Addison's disease), but, in general, sodium and chloride concentrations are not as high as in CFP. On the other hand, pituitary hypofunction is not followed by abnormal salt excretion