Hypokalemia Health Article

Symptoms

Mild hypokalemia usually results in no symptoms, while moderate hypokalemia results in confusion, disorientation, weakness, and discomfort of muscles. On occasion, moderate hypokalemia causes cramps during exercise. Another symptom of moderate hypokalemia is a discomfort in the legs that is experienced while sitting still. The patient may experience an annoying feeling that can be relieved by shifting the positions of the legs or by stomping the feet on the floor. Severe hypokalemia results in extreme weakness of the body and, on occasion, in paralysis. The paralysis that occurs is "flaccid paralysis," or limpness. Paralysis of the muscles of the lungs results in death. Another dangerous result of severe hypokalemia is abnormal heart beat (arrhythmia) that can lead to death from cardiac arrest (cessation of heart beat). Moderate hypokalemia may be defined as serum potassium between 2.5 and 3.0 mM, while severe hypokalemia is defined as serum potassium under 2.5 mM.

Diagnosis

Hypokalemia can be measured by acquiring a sample of blood, preparing blood serum, and using a potassium sensitive electrode for measuring the concentration of potassium ions. Atomic absorption spectroscopy can also be used to measure the potassium ions. Since hypokalemia results in abnormalities in heart behavior, the electrocardiogram is usually used in the diagnosis of hypokalemia. The diagnosis of the cause of hypokalemia can be helped by measuring the potassium content of the urine. Where urinary potassium is under 25 mmoles per day, it means that the patient has experienced excessive losses of potassium due to diarrhea. The urinary potassium test is useful in cases where the patient is denying the practice of laxative or enema abuse. In contrast, where hypokalemia is due to the use of diuretic drugs, the content of potassium in the urine will be high—over 40 mmoles per day.

Treatment

In emergency situations, when severe hypokalemia is suspected, the patient should be put on a cardiac monitor, and respiratory status should be assessed. If laboratory test results show potassium levels below 2.5 mM, intravenous potassium should be given. In less urgent cases, potassium can be given orally in the pill form. Potassium supplements take the form of pills containing potassium chloride (KCl), potassium bicarbonate (KHCO₃), and potassium acetate. Oral potassium chloride is the safest and most effective treatment for hypokalemia. Generally, the consumption of 40–80 mmoles of KCl per day is sufficient to correct the hypokalemia that results from diuretic therapy. For many people taking diuretics, potassium supplements are not necessary as long as they eat a balanced diet containing foods rich in potassium.

Prognosis

The prognosis for correcting hypokalemia is excellent. However, in emergency situations, where potassium is administered intravenously, the physician must be careful not to give too much potassium. The administration of potassium at high levels, or at a high rate, can lead to abnormally high levels of serum potassium.

Prevention

Hypokalemia is not a concern for healthy persons, since potassium is present in a great variety of foods. For patients taking diuretics, however, the American Dietetic Association recommends use of a high potassium diet. The American Dietetic Association states that if hypokalemia has already occurred, use of the high potassium diet alone may not reverse hypokalemia. Useful components of a high potassium diet include bananas, tomatoes, cantaloupes, figs, raisins, kidney beans, potatoes, and milk.

BOOKS

American Dietetic Association. Handbook of Clinical Dietetics. New Haven, CT: Yale University Press, 1992.

Brody, Tom. Nutritional Biochemistry. San Diego: Academic Press, 1998.

Harrison's Principles of Internal Medicine. Ed. Anthony S. Fauci, et al. New York: McGraw-Hill, 1997.

Singer, Gary G., and Barry M. Brenner. "Fluid and Electrolyte Disturbances." In Harrison's Principles of Internal Medicine, ed. Anthony S. Fauci, et al. New York: McGraw-Hill, 1997.

Zeman, F., and D. M. Dey. Applications in Medical Nutrition Therapy. 2nd ed. Engelwood Cliffs, NJ: Prentice-Hall, 1995.

PERIODICALS

Wingo, I. D., and C. S. Wingo. "Hypokalemia—Consequences, Causes, and Correction." Journal of the American Society of Nephrology 8 (1997): 1179-1188.

Tom Brody, PhD

KEY TERMS

Diuretics—A class of drugs that cause the kidneys to excrete excess sodium, water, and potassium.

pH—The unit of acid content is pH. The blood plasma normally has a pH of 7.35–7.45. Acidic blood has a pH value slightly less than pH 7.35. Alkaline blood has a pH value slightly greater than pH 7.45.

Potassium—An electrolyte necessary to proper functioning of the body.