Urinary chloride excretion distinguishes between renal and extrarenal metabolic alkalosis

The aetiology of normotensive hypokalaemic metabolic alkalosis is sometimes not obtainable from the history. Observations in adults indicate that the urinary chloride excretion is low in metabolic alkalosis of extrarenal origin. The chloride/creatinine ratio in random urines was therefore compared in 283 healthy children and in eight paediatric patients with metabolic alkalosis. The urinary chloride/creatinine ratio was reduced in four patients with metabolic alkalosis of extrarenal origin and within reference values or above in four patients with metabolic alkalosis of renal origin.

The study confirms that urinary chloride/creatinine ratio discriminates between extrarenal and renal forms of metabolic alkalosis.