Urinary loss
Certain medications can cause excess potassium loss in the urine. Blood pressure medications such as loop diuretics (e.g. furosemide) and thiazide diuretics (e.g. hydrochlorothiazide) commonly cause hypokalemia. Other medications such as the antifungal amphotericin B or the cancer drug cisplatin can also cause long-term hypokalemia. Diuretic abuse among athletes and people with eating disorders may present with hypokalemia due to urinary potassium loss. A special case of potassium loss occurs with diabetic ketoacidosis. Hypokalemia is observed with low total body potassium and a low intracellular concentration of potassium. In addition to urinary losses from polyuria and volume contraction, also an obligate loss of potassium from kidney tubules occurs as a cationic partner to the negatively charged ketone, β-hydroxybutyrate. A low level of magnesium in the blood can also cause hypokalemia. Magnesium is required for adequate processing of potassium. This may become evident when hypokalemia persists despite potassium supplementation. Other electrolyte abnormalities may also be present. An increase in the pH of the blood (alkalosis) can cause temporary hypokalemia by causing a shift of potassium out of the plasma and interstitial fluids into the urine via a number of interrelated mechanisms.1) Type B intercalated cells in the collecting duct reabsorb H+ and secrete HCO3, while in type A intercalated cells protons are secreted via both H+-K+ATPases and H+ ATP-ases on the apical/luminal surface of the cell. By definition, the H+-K+ATPase reabsorbs one potassium ion into the cell for every proton it secretes into the lumen of the collecting duct of a nephron.
See also
Bartter syndrome
Gitelman syndrome
Hypokalemic acidosis
Potassium deficiency (plant disorder)
Superior mesenteric artery syndrome

References
Further reading
Firth, J (2010). "Disorders of potassium homeostasis". In David A. Warrell; Timothy M. Cox; John D. Firth; Graham S. Ogg (eds.). Oxford Textbook of Medicine. Vol. 1 (5th ed.). Oxford: Oxford University Press. pp. 3831–3845. doi:10.1093/med/9780199204854.003.210202_update_001. ISBN 978-0199204854. Greenlee, M; Wingo, CS; McDonough, AA; Youn, JH; Kone, BC (May 5, 2009). "Narrative review: evolving concepts in potassium homeostasis and hypokalemia" (PDF). Annals of Internal Medicine. 150 (9): 619–25. doi:10.7326/0003-4819-150-9-200905050-00008. PMC 4944758. PMID 19414841. NIHMSID: NIHMS800438. External links
Content of Selected Foods per Common Measure, sorted by nutrient content (Potassium)
List of foods rich in potassium (U. Mass. Med.) National Organization for Rare Disorders: Hypokalemia