Figure 3.

The urine chloride concentration can be used to distinguish between a chloride responsive and resistant metabolic alkalosis. In a normal gap metabolic acidosis due to diarrhea, a high urine chloride is the result of increased excretion of NH₄Cl. Urine chloride is high in kidney tubular acidosis due to acidosis-induced decreased reabsorption of NaCl in the proximal tubule. In the indicated causes of anion gap metabolic acidosis, a high urine chloride is the result of increased excretion of NH₄Cl. In these settings, the urine sodium is typically higher than the chloride due to the excretion of sodium and potassium acid salts.