Low Potassium (Hypokalemia)
Benjamin Wedro, MD, FACEP, FAAEM
Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.
Melissa Conrad Stöppler, MD
Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.
What is potassium?
Potassium is one of the primary electrolytes (crucial chemicals for cell function), and is concentrated within the cells of the body. Only 2% of the body's total potassium is available in the serum or blood stream. Small changes in the serum levels of potassium can affect body function. One of the more important functions of potassium is to maintain the electrical activity of the cells in the body. Cells with high electrical activity (for example, nerves and muscles, including the heart) are particularly affected when potassium levels fall.
Normal serum potassium levels range from 3.5 to 5.0 mEq/liter in the blood. Normal daily intake of potassium is 70-100 mEq (270 to 390 mg/dl), and requires the kidneys to remove that same amount each day. If more is removed, the body's total potassium store will be decreased, and the result is hypokalemia (hypo=low + kal=potassium +emia= in the blood) occurs.
Potassium enters the body through dietary intake. Examples of potassium rich foods include:
- Fresh fruits: bananas, cantaloupe, oranges, strawberries, kiwi, avocados, apricots
- Fresh vegetables: greens, mushrooms, peas, beets, tomatoes
- Meats: beef, fish, turkey,
- Juices: Orange, prune, apricot, grapefruit
What are the causes of low potassium (hypokalemia)?
Hypokalemia is not commonly caused by poor dietary intake.
The most common reason that potassium levels fall is due to the loss from the gastrointestinal (GI) tract and the kidney.
Potassium loss from the GI tract may be caused by:
- Ileostomy: In some patients who have had bowel surgery and have an ileostomy, the stool output can contain significant amounts of potassium.
- Villous adenoma (a type of colon polyp that can cause the colon to leak potassium)
- Laxative use
Causes of potassium loss from the kidney:
- Diuretic medications (water pills) like hydrochlorothiazide (HCTZ) or furosemide (Lasix)
- Elevated corticosteroid levels, either from medication like prednisone or from an illness like Cushing's Syndrome
- Elevated levels of aldosterone, a hormone that can increase with renal artery stenosis or adrenal tumors
- Renal tubular acidosis
- Low body magnesium levels
Low potassium levels may result from side effects of some medications:
- Aminoglycosides like gentamicin (Garamycin) or tobramycin (Nebcin)
- Amphotericin B
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