A 64-year-old woman has metabolic alkalosis and the bicarbonate level is 34 mEq/L. Which of the following is the most likely cause?

Diuretics are a common cause for metabolic alkalosis since many patients take these medications for hypertension or CHF. Diarrhea causes a non-anion gap metabolic acidosis, and mineralocorticoid excess leads to metabolic alkalosis, primarily because of renal bicarbonate generation. Other major mechanisms for metabolic alkalosis include extracellular fluid (ECF) volume contraction, potassium depletion, and increased distal salt delivery. Less common causes are Liddle syndrome, bicarbonate loading (post hypercapnic alkalosis), and delayed conversion of administered organic acids.