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Hypokalemia

Definition

Hypokalemia is a lower-than-normal amount of potassium in the blood.

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Alternative Names

Potassium - low; Low blood potassium

Causes, incidence, and risk factors

Potassium is needed for cells, especially nerve and muscle cells, to function properly. You get potassium through food. The kidneys remove excess potassium in the urine to keep a proper balance of the mineral in the body.

Hypokalemia is a metabolic disorder that occurs when the level of potassium in the blood drops too low.

Possible causes of hypokalemia include:

Antibiotics (penicillin, nafcillin, carbenicillin, gentamicin, amphotericin B, foscarnet)
Diarrhea (including the use of too many laxatives, which can cause diarrhea)
Diseases that affect the kidneys' ability to retain potassium (Liddle syndrome, Cushing syndrome, hyperaldosteronism, Bartter syndrome, Fanconi syndrome)
Diuretic medications, which can cause excess urination
Eating disorders (such as bulimia)
Eating large amounts of licorice or using products such as herbal teas and chewing tobaccos that contain licorice made with glycyrrhetinic acid (this substance is no longer used in licorice made in the United States)
Magnesium deficiency
Sweating
Vomiting

Symptoms

A small drop in potassium usually doesn't cause symptoms. However, a big drop in the level can be life threatening.

Symptoms of hypokalemia include:

Abnormal heart rhythms (dysrhythmias), especially in people with heart disease
Constipation
Fatigue
Muscle damage (rhabdomyolysis)
Muscle weakness or spasms
Paralysis (which can include the lungs)

Signs and tests

Your health care provider will take a sample of your blood to check potassium levels.

Other tests might include:

Arterial blood gas
Basic or comprehensive metabolic panel
Electrocardiogram (ECG)
Blood tests to check glucose, magnesium, calcium, sodium, phosphorous, thyroxine, and aldosterone levels

Treatment

Mild hypokalemia can be treated by taking potassium supplements by mouth. Persons with more severe cases may need to get potassium through a vein (intravenously).

If you need to use diuretics, your doctor may switch you to a form that keeps potassium in the body (such as triamterene, amiloride, or spironolactone).

One type of hypokalemia that causes paralysis occurs when there is too much thyroid hormone in the blood (thyrotoxic periodic paralysis). Treatment lowers the thyroid hormone level, and raises the potassium level in the blood.

Expectations (prognosis)

Taking potassium supplements can usually correct the problem. In severe cases, without proper treatment a severe drop in potassium levels can lead to serious heart rhythm problems that can be fatal.

Complications

In severe cases, patients can develop paralysis that can be life threatening. Hypokalemia also can lead to dangerous irregular heartbeat. Over time, lack of potassium can lead to kidney damage (hypokalemic nephropathy).

Calling your health care provider

Call your health care provider if you have been vomiting or have had excessive diarrhea, or if you are taking diuretics and have symptoms of hypokalemia.

Prevention

Eating a diet rich in potassium can help prevent hypokalemia. Foods high in potassium include:

Avocados
Bananas
Bran
Carrots
Dried figs
Kiwi
Lima beans
Milk
Molasses
Oranges
Peanut butter
Peas and beans
Seaweed
Spinach
Tomatoes
Wheat germ

References

Mount DB, Zandi-Nejad K. Disorders of potassium balance. In: Brenner BM, ed. Brenner and Rector's The Kidney. 8th ed. Philadelphia, Pa: Saunders Elsevier; 2008:chap 15.

Seifter JL. Potassium disorders. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 118.

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