Última actualización:
February 02, 2008
Años publicados: 1990, 2003
Hypokalemia is a metabolic imbalance characterized by extremely low potassium levels in the blood. It is a symptom of another disease or condition, or a side effect of diuretic drugs. The body needs potassium for the contraction of muscles (including the heart), and for the functioning of many complicated proteins (enzymes). Potassium is found primarily in the skeletal muscle and bone, and participates with sodium to contribute to the normal flow of body fluids between the cells in the body. The normal concentration of potassium in the body is regulated by the kidneys through the excretion of urine. When the kidneys are functioning normally, the amount of potassium in the diet is sufficient for use by the body and the excess is usually excreted through urine and sweat. Body chemicals and hormones such as aldosterone also regulate potassium balance. Secretion of the hormone insulin, which is normally stimulated by food, prevents a temporary diet-induced Hypokalemia by increasing cell absorption of potassium. When Hypokalemia occurs, there is an imbalance resulting from a dysfunction in this normal process, or the rapid loss of urine or sweat without replacement of sufficient potassium.
Most often, hypokalemia is asymptomatic, with no obvious signs of the disorder. However, symptoms of hypokalemia may include attacks of severe muscle weakness, eventually leading to paralysis and possibly respiratory failure.
Muscular malfunction may result in paralysis of the bowel, low blood pressure, muscle twitches and mineral deficiencies (tetany). Severe hypokalemia may also lead to disruption of skeletal muscle cells, particularly during exercise. The normal physical response to exercise requires the local release of potassium from muscle. In potassium depleted muscle, the lack of potassium prevents adequate widening of blood vessels, resulting in decreased muscle blood flow, cramps and the destruction of skeletal muscle.
Hypokalemia may also impair the ability of the kidneys to concentrate urine, resulting in excessive urination (polyuria) and excessive thirst (polydipsia). Other symptoms may include loss of appetite, nausea and vomiting. There may also be heart irregularities seen in electrocardiograph changes, confusion, distention of the abdomen, a decrease in mental activity.
Hypokalemia always occurs as a result of excessive loss of potassium through the urine, sweat or stool. It is always a symptom of another disorder, rather than a disease that occurs by itself.
The excessive excretion of potassium in the urine (kaliuresis) may result from the use of diuretic drugs (which increases urination), a deficiency of magnesium in the blood, excessive mineralocorticoids such as aldosterone in the blood which affect the electrolyte and fluid balance in the body (usually caused by endocrine diseases), kidney disorders, or from the use of high doses of penicillin. Gastrointestinal losses of potassium usually are due to prolonged diarrhea or vomiting, chronic laxative abuse, inadequate dietary intake of potassium, intestinal obstruction or infections such as fistulas in the intestines which continually drain intestinal fluids. Additionally, excessive perspiration due to hot weather or exercise can cause hypokalemia.
Hypokalemia may affect both males and females. However, it occurs more commonly in females.
The underlying cause of Hypokalemia must first be treated. When the hypokalemia is severe, potassium chloride may be administered orally or intravenously. Treatment must be carefully monitored by a physician. Any associated acid-base disorders or hormonal disturbances must be evaluated before treatment is planned. The administration of potassium and potassium- sparing diuretics is usually discouraged in patients with kidney disease, diabetes mellitus, or dysfunctions of the autonomic nervous system. The imbalance of external and internal potassium levels in these individuals may predispose them to life-threatening degrees of Hyperkalemia (too much potassium). Hypokalemia in individuals with high blood pressure taking diuretics may be improved by replacing lost potassium in the diet through certain fruits or potassium drugs. Hypokalemia may also be minimized by dietary restriction of salt since high rates of sodium excretion promote urinary potassium losses. People who participate in vigorous sports or exercise in warm weather should be sure to replace potassium that is lost through excessive sweating. This can be accomplished through dietary planning.
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TEXTBOOKS
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REVIEW ARTICLES
Fervenza FC, Rabkin R. The role of growth factors and ammonia in the genesis of hypokalemic nephropathy. J Ren Nutr. 2002;12:151-59.
Gennari FJ. Disorders of potassium homeostasis. Hypokalemia and hyperkalemia. Crit Care Clin. 2002;18:273-88,vi.
Riggs JE. Neurologic manifestations of electrolyte disturbances. Neurol Clin. 2002;20:227-39, vii.
Shaer AJ. Inherited primary renal tubular hypokalemic alkalosis: a review of Gitelman and Barterr syndromes. Am J Med Sci. 2001;322:316-32.
Rastegar A, Soleimani M, Rastergar A. Hypokaelemia and hyperkaelemia. Postgrad Med J. 2001;77:759-64.
Schepkens H, Lameire N. Gitelman’s syndrome: an overlooked cause of chronic hypokalemia and hypoimagnesemia in adults. Acta Clin Belg. 2001;56:248-54.
Kapoor M, Chan GZ. Fluid and electrolyte abnormalities. Crit Care Clin. 2001;17:503-29.
FROM THE INTERNET
Salem MM, Batlle DC. Hyperkalemia and hypokalemia. Best Practice of Medicine. Last modified: April 2, 2001:18pp.
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