Potassium is an electrolyte substance that is necessary for survival. It facilitates various cellular functions and is especially important for nerves, muscles, and the heart's electrical system. In order to maintain these functions, the body regulates the amount of potassium in the body. Even so, consequences may ensue when there is too much or too little potassium.
Regulation of Potassium
Potassium is obtained from one's diet in foods such as various fruits and meats. It is entirely absorbed into the bloodstream from the digestive system and predominantly stays within the body's cells. Normally, the human body maintains a serum potassium level between 3.5 and 5.3 milliequivalents per liter (mEq/L).
Most excess potassium is eliminated from the body through the kidneys. When blood passes through these organs, fluid and small substances, including potassium, are filtered into the tubules of the kidneys. Most of this filtrate is reabsorbed back into the blood. If potassium needs to be excreted, the kidneys can secrete it into their own collecting ducts, mediated by a hormone called aldosterone. Meanwhile; a small amount of potassium is excreted from the body by secretion into the colon of the gastrointestinal tract.
Hyperkalemia
Hyperkalemia is defined as a serum potassium level greater than 5.3 mEq/L. This often occurs with kidney failure, particularly when the patient increases his or her intake of potassium. In addition, hyperkalemia can result from drugs that inhibit potassium excretion (e.g., potassium-sparing diuretics) and conditions that shift potassium out of cells, such as destruction of skeletal muscle (rhabdomyolysis) and destruction of tumor cells following chemotherapy (tumor lysis).
Symptoms of hyperkalemia stem from effects on skeletal muscles and the heart, including fatigue, weakness, and palpitations. Treatment of hyperkalemia first requires restriction of potassium intake. From there, methods to lower serum potassium include glucose and insulin to stimulate cellular uptake of potassium, saline and diuretics to increase urine production and renal potassium excretion, Kayexalate to increase gastrointestinal secretion of potassium, and, as a last resort, emergency dialysis.
Hypokalemia
Hypokalemia is when the serum potassium level is less than 3.5 mEq/L. Many causes of hypokalemia are the reverse of those of hyperkalemia. For example, patients with hypokalemia may have inadequate intake of potassium coupled with use of diuretic drugs or excessive aldosterone (hyperaldosteronism). A common cause of hypokalemia is diarrhea because of potassium loss via the gastrointestinal tract.
The symptoms of hypokalemia are similar to those of hyperkalemia: fatigue, weakness, and palpitations. Treatment involves stopping any medications that contribute to hypokalemia and providing potassium supplementation orally or through an intravenous line.
References
 |
