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Hypokalemia (Low Potassium)

BAMI.us
On this page: Causes | Symptoms | Treatment | Foods High in Potassium
Potassium is an electrolyte...  

Microscope and Test TubeElectrolytes are minerals in your blood and other body fluids and can be measured by a blood test. Potassium is an electrolyte that is critical to the function of nerve and muscles cells, including those in your heart. The level of potassium in the blood must be maintained within a narrow range. When potassium levels are too high or too low, it can increase the risk of an abnormal heartbeat and have serious consequences, such as a life-threatening rhythm disturbance or even cardiac arrest.

Our body naturally maintains it's own potassium balance within the normal range. 98% of the body's potassium is located inside the cells. Only 2% is located in the blood, outside the cells, which is the part that we measure by a blood test. The potassium stored within the cells can be used by the body to help maintain a constant level of potassium in the blood.

Potassium balance is achieved by matching the amount of potassium taken in with the amount lost. Potassium is taken in through food and electrolyte-containing drinks and lost primarily in urine, although some potassium is also lost through the digestive tract and in sweat. Healthy kidneys are able to adjust the excretion of potassium to match changes in dietary intake. Some drugs and certain conditions affect the movement of potassium into and out of cells, which greatly influences the potassium level in the blood.

Potassium levels, along with other electrolyte levels, are often part of routine blood work, but may be ordered at regular intervals to monitor therapy with certain drugs and in patients with certain chronic diseases. Normal potassium values may vary from lab to lab. In general normal values fall within the following ranges:

Normal Potassium Lab Values
Adults: 3.5–5.0 milliequivalents per liter (mEq/L); Children: 3.4–4.7 mEq/L (Infants and newborns have different normal ranges)
Note: Lab errors can occur with potassium levels--if the result is unexpectedly high, the doctor might repeat the blood test to confirm accuracy.
Dietary Requirements of Potassium from the Food and Nutrition Board 2004(2)

A balanced diet generally contains enough potassium to keep the blood levels within a normal range. Blood potassium abnormalities usually arise due to a disease or medication.

Nonetheless, studies have shown that for optimal health, adults should consume at least 4.7 grams of potassium per day. This amount has been shown to help lower blood pressure, blunt the effects of salt, and reduce the risk of kidney stones and bone loss. However, most American women 31 to 50 years old consume no more than half of the recommended amount of potassium, and men's intake is only moderately higher.(2)

Causes of Hypokalemia (Low Potassium)

Hypokalemia may result from many different conditions. The most common cause is excessive potassium loss in the urine or from the gastrointestinal tract, such as due to:

  • Use of diuretics
  • Dehydration
  • Severe vomiting or diarrhea
  • Excessive use of laxatives
  • Excessive sweating
  • Impaired kidney function
  • Excessive production of the hormone aldosterone (hyperaldosteronism) by the adrenal gland
  • Rarely, hypokalemia can be due to inadequate potassium in the diet.
Symptoms of Hypokalemia (Low Potassium)

A mild decrease in the potassium level in the blood usually causes no symptoms. A more severe decrease can cause muscle weakness, twitches, and even paralysis. Abnormal heart rhythms may develop, especially in people with heart disease. Even mild hypokalemia is dangerous in people taking the heart drug digoxin (Lanoxin)(3)

Treatment of Hypokalemia

Treatment varies depending on the underlying cause of the low potassium. Treatment may be directed at eliminating the cause of the low potassium, or may include eating foods high in potassium or require taking potassium supplements by mouth.

Potassium supplements can irritate the digestive tract and large doses should be divided into smaller doses, and given with food, several times a day rather than in a single daily dose. Special types of potassium supplements, such as wax-impregnated or microencapsulated potassium chloride, are much less likely to irritate the digestive tract.

Follow-up potassium levels will be ordered by your physician to monitor treatment.
Foods high in potassium Note: Some foods high in potassium are also high in calories.
Milk
All milk, skim, whole, buttermilk, yogurt (1 cup)*
Chocolate milk, low fat 1 cup 425 mg
Vegetables
Artichokes (1 whole)*
Asparagus (1 cup)*
Beans, dried (1/3 cup)*
Beet greens (1 cup)*
Bamboo shoots (1/2 cup)*
Broccoli (2 stalks)*
Brussel sprouts (1/2 cup)*
Celery (1 cup)*
Chard (1/2 cup)*
Chinese cabbage (2 cups)*
Lettuce (2 cups)*
Mushrooms (1 cup)*
Parsnips (1/2 cup)*
Pinto beans 1 cup 583 mg
Potato, baked 1 medium 610 mg
Pumpkin (1/2 cup)*
Spinach 1 cup, cooked 574 mg
Squash (Acorn) 1 cup, cubed 896 mg
Squash (summer) (1 cup)*
Squash (winter) (3/4 cup)*
Sweet Potato (1 cup) baked 950 milligrams (mg)
Tomato (1 medium)*
Tomato juice 8 ounces (oz.) 556 mg
Fruits
Apricots, dried 1/3 cup 734 mg
Avocado (1/3 whole)*
Banana 1 medium 422 mg
Cantaloupe 1 cup, balls 473 mg
Dates (5 medium)*
Figs, dried (3 medium)*
Grapefruit juice (1 cup)*
Honeydew melon (2" wide slice of 6" diameter melon)*
Orange (1 medium or 3/4 cup sections)*
Orange juice, fresh squeezed 8 oz. 496 mg
Papaya 1 medium 781 mg
Peaches, dried (1/2 cup)*
Prune juice (1/2 cup)*
Prunes (5 large)*
Raisins (1/3 cup)*
Other--these foods and food additives are generally high in potassium
  • Salt substitutes (listed as KCl on labels)
  • Lite salts,
  • Coffee,
  • Sport drinks,
  • Iced tea sold in cans
  • Granola bars,
  • Ovaltine,
  • Chocolate and
  • Fig cookies
  • Molasses (Blackstrap) 1 tablespoon 498 mg
*The following foods, in listed portion sizes, have greater than 275 mg (7mEq) potassium per serving.
References
1) Potassium from the American Heart Association
2) Dietary Reference Intakes from the Institute of Medicine
3) Potassium from MerckSource.com
--Written by N Thompson, ARNP and reviewed by Michael Thompson, MD, Internal Medicine, Updated February 2009

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