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Hypokalemia is a condition in which the body fails to retain sufficient potassium to maintain health. The condition is also known as potassium deficiency. The prefix hypo- means low (contrast with hyper-, meaning high). The middle kal refers to kalium, which is Latin for potassium. The end portion of the word, -emia, means 'in the blood' (note, however, that hypokalemia is usually indicative of a systemic potassium deficit).
Causes Hypokalemia can result from a variety of medical conditions. Perhaps most obviously, insufficient consumption of potassium (that is, a low-potassium diet) can result in the condition. More commonly, however, hypokalemia occurs due to excessive loss of potassium, often associated with excess water loss, which 'flushes' potassium out of the body. Typically, this is a consequence of vomiting and diarrhea. Certain medications can also accelerate the removal of potassium from the body, including loop diuretics, such as furosemide or bumetanide, as well as various laxatives. Often doctors and pharmacists will suggest changes in their patients' diets to compensate for the effects of medication - for instance, recommending that a patient eat a (potassium-rich) banana daily; sometimes, doctors will co-prescribe a potassium supplement with a potassium-depleting drug.
Effects Potassium is essential for many body functions, including muscle and nerve activity. Potassium is the principal intracellular cation, with a concentration of about 145 mEq/L, as compared with a normal value of about 4 mEq/L in extracellular fluid, including blood. More than 98% of the body's potassium is intracellular; measuring it from a blood sample is relatively insensitive, with small fluctuations in the blood corresponding to very large changes in the total bodily reservoir of potassium.
The osmotic gradient of potassium between intracellular and extracellular space is essential for nerve function; in particular, potassium is needed to repolarize the cell membrane to a resting state after an action potential has passed.
Potassium is also essential to the normal muscular function, in both voluntary muscle (e.g. the arms and hands) and involuntary muscle (e.g. the heart and intestines). Severe abnormalities in potassium levels can seriously disrupt cardiac function, even to the point of causing cardiac arrest and death.
Potassium in the diet It is usually easy to obtain adequate potassium in a normal balanced diet. Potassium is found in many foods, including oranges and bananas (high quantities), potatoes, avocadoes, spinach, lima beans, tomato and vegetable juices, dried fruits, including raisins, meats, milk, cooked dried beans, mushrooms, and peanut butter.
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