In evaluating hyperkalemia, a low urine chloride most strongly suggests potassium loss due to what cause?

In evaluating hyperkalemia, a low urine chloride most strongly suggests potassium loss due to what cause?

• A. Adrenal insufficiency
• B. Kidney failure
• C. Diuretic use
• D. Diarrhea

Answer: (D)

A low urine chloride points to potassium loss outside the kidneys. When potassium is lost through the GI tract, as with diarrhea, the body is volume-depleted and the kidney conserves chloride and potassium to maintain electroneutrality, so urinary chloride falls. This extrarenal potassium loss pattern is what a low urine chloride most strongly signals. In contrast, potassium loss originating in the kidney (as with kidney failure or diuretic use) tends to be associated with higher urinary chloride due to renal excretion or diuretic-driven chloride loss, and adrenal insufficiency causes hyperkalemia through reduced aldosterone without the same GI-loss–driven chloride conservation signal. Therefore diarrhea best fits the finding of a low urine chloride in hyperkalemia.

A low urine chloride points to potassium loss outside the kidneys. When potassium is lost through the GI tract, as with diarrhea, the body is volume-depleted and the kidney conserves chloride and potassium to maintain electroneutrality, so urinary chloride falls. This extrarenal potassium loss pattern is what a low urine chloride most strongly signals.

In contrast, potassium loss originating in the kidney (as with kidney failure or diuretic use) tends to be associated with higher urinary chloride due to renal excretion or diuretic-driven chloride loss, and adrenal insufficiency causes hyperkalemia through reduced aldosterone without the same GI-loss–driven chloride conservation signal. Therefore diarrhea best fits the finding of a low urine chloride in hyperkalemia.