In 1980, a small group of infants were identified whose initial signs and symptoms included failure to thrive, lethargy, anorexia, and weakness. Initial electrolyte determinations indicated a severe metabolic alkalosis with hypochloremia and hypokalemia. In subsequent investigations by the Centers for Disease Control, a large number of infants with the same signs and symptoms and biochemical abnormalities were identified. All of these infants were found to be ingesting formulas markedly chloride deficient. In studies of this group of infants with dietary chloride deficiency, high levels of renin and aldosterone were found. The postulated mechanism for the underlying electrolyte abnormalities was the deficiency of chloride in the diet that caused extra-cellular volume contraction, stimulating the release of renin and aldosterone.