Chloride is the most abundant ion outside of cells. It is important for maintaining osmotic pressure, nerve cell function, and fluid balance. The urine chloride test is used primarily in cases of suspected metabolic alkalosis. Under normal circumstances, sodium and urine are excreted into the urine at a steady, equal rate. Plasma levels of chloride tend to mirror those of sodium (i.e., as sodium levels increase in plasma, chloride levels increase). Nevertheless, urine chloride levels can be used to investigate certain diseases and disorders, though urine chloride levels are rarely measured alone. Most often, they are measured in conjunction with urine pH, sodium, and potassium levels. A urine chloride test may also be ordered along with other labs needed to diagnose metabolic alkalosis and other acid-base disturbances, such as arterial blood gases. Acetazolamide, corticosteroids, NSAIDs, and diuretics can interfere with the test.
Normal Ranges for Urine Chloride:
40-224 mmol/24 hours