[Metabolic alkalosis and secondary hyperaldosteronism in cystic fibrosis (author's transl)].

The prolonged use of a salt restricted infant formula (1.9 mEq Na/kg/day and 1,4 mEq C1/kg/day) in a child with undiagnosed cystic fibrosis led to a life threatening metabolic disturbance. The main features were hypochloraemic alkalosis due to massive loss of electrolytes in the sweat. Urinary electrolyte excretion, however, had been lowered to a minimum due to aldosteron induced reabsorption. Plasma aldosterone levels were initially high, but returned to normal after addition of salt to the feeds. Prior to admission a sweat test had been negative. The patient clearly demonstrates the unique metabolic feature of cystic fibrosis of the ability to retain electrolytes in the tubulus and at the same time the inability of the sweat glands to reabsorb sodium and chloride. Contrary to present experience severe prolonged salt restriction is believed to be able to diminish sweat electrolytes to subpathological values.