The potassium ion is needed for the transmission of electricity across cell membranes. Potassium is also needed for adequate functioning of the heart, muscles and neurons. The kidneys routinely excrete potassium; kidney failure slows the rate of potassium excretion, which leads to potassium accumulation in the body. Dialysis removes excess potassium and wastes from the body.
Sources of Potassium
Potassium is mostly absorbed from foods. Bananas are the most recognized source of potassium, but other sources include meats, fish, vegetables, legumes and fruits.
Excess Potassium
Hyperkalemia, or excess potassium, is recognized as a blood potassium concentration greater than 5 milliequivalents per liter, or mEq/L. There is a constant efflux, or outflow, of potassium from the cell to the interstitial space and into the bloodstream. Potassium is then excreted by the kidneys at a rate dependent on age, underlying diseases and other factors. Older people filter blood more slowly than younger people and are more susceptible to hyperkalemia. Excess intake of potassium can lead to hyperkalemia. Excess destruction of cells by trauma, inflammation, infection or chemical action can also cause hyperkalemia.
Complications
The most worrisome complication of hyperkalemia is one that involves the heart. Heart function is strongly dependent on potassium concentration and is most likely to be affected in hyperkalemia. Hyperkalemia interferes with heart rhythm regulation, making it difficult to pump blood adequately. Hyperkalemia may also cause muscle weakness.
Dialysis and Other Treatments
Acute ingestion of high amounts of potassium can be managed by administrating sodium polystyrene sulfonate, a molecule that traps potassium and prevents its absorption in the gut. Severe potassium elevation is managed by dialysis, which removes potassium and wastes from the blood. Dialysis also treats volume overload, or excess fluid, and the altered mental status that may be seen in renal failure.
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