Potassium is critical to the function of organs such as the heart as well as the nerves and muscles. It is a nutrient that is found in many foods. In the body, it is an electrolyte that has the ability to conduct electricity. For potassium to help the body work efficiently, it needs to be present at certain levels. When too much or too little potassium is present in the serum--a component of blood--mild to severe symptoms can occur.
Functions
Potassium is an important part of cell membrane potential. Membrane potential is a condition where the level of potassium in the cell is greater than the level outside the cell in the serum. Coordinated changes in membrane potential--movement of potassium into or out the cell--produce electricity for activities like muscle contraction. Heart function, nerve impulse transmission and muscle contraction require strict control of membrane potential in order to occur properly. Therefore, potassium is crucial to body processes such as digestion and the rate at which the heart beats. Certain enzymes such as pyruvate kinase, an enzyme involved in carbohydrate metabolism, need potassium in order to work.
Deficiency
When a person's serum potassium level is abnormally low, a condition called hypokalemia, certain symptoms occur. Persons who have this condition may experience muscle weakness, muscle aches, cramps, abdominal pain, constipation or a life-threatening condition called ventricular arrhythmia. In ventricular arrhythmia, the heart beats abnormally. It actually quivers and is unable to pump blood efficiently.
Excess
Hyperkalemia refers to abnormally high levels of potassium in the serum. The Linus Pauling Institute explains that the most significant effect of this imbalance is seen in the heart. Hyperkalemia can cause abnormal heart rhythms which could make the heart stop beating, a condition also referred to as cardiac arrest.
Causes
Hypokalemia can be caused by inadequate intake of dietary potassium. However, this is a rare occurrence. A common cause of this disorder is loss of potassium through the gastrointestinal tract via vomiting and diarrhea. Certain medications and kidney disease stimulate loss of potassium through the urine and can cause hypokalemia. Some diseases, such as a genetic disease called Bartter syndrome, can also result in hypokalemia.
Causes of hyperkalemia include excessive intake of potassium in the diet or potassium supplements. It can also occur when the kidneys are not able to excrete potassium as usual due to kidney disease or intake of certain drugs or because of low levels of a hormone called aldosterone that stimulates the kidneys to excrete potassium and more sodium. Potassium-sparing diuretics may cause hyperkalemia. They are drugs that facilitate water removal from the body but conserve potassium.
Expert Insight
The Linus Pauling Institute recommends increasing daily intake of potassium to at least 4.7 g. This can be done by increasing dietary consumption of potassium-rich foods. Fruits and vegetables are the richest sources of potassium. The American Heart Association explains that bananas, grapefruit, oranges, prunes, tomatoes and molasses are foods that are high in potassium. Certain individuals may be required to consume less potassium due to medical conditions. Therefore, it is best to consult a physician before embarking on any diet changes.
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