Potassium is a mineral. In the human body, it exists as an electrolyte, which is a charged mineral. It is ingested in the diet and largely regulated by the kidneys. It plays a key role in the electrical energy of cells. Many conditions can cause excessive or depleted potassium levels, which can disrupt cellular function, particularly in the nervous and muscular tissues. Dietary choices and the diagnosis and treatment of disease should be undertaken with the consultation of a health-care professional.
Sources
Many fruits, vegetables and low fat dairy products are good sources of potassium. Some specific foods include bananas, grapefruit, cantaloupe, oranges, honeydew melons, tomato or prune juice, prunes, potatoes and molasses. Meats, poultry and fish are also high in potassium.
Range and Regulation
The normal range of potassium in the blood as reported by most labs is 3.5 mEq/L to 5.0 mEq/L. These values are determined by surveying thousands of people, finding the average potassium level among them, and how far the levels tend to deviate in healthy people. The level of potassium in the blood is largely regulated by the kidneys, which can conserve potassium or release it into the urine.
Functions
The concentration of potassium inside of cells is much higher than outside of cells, while the opposite is true of sodium. These electrically and magnetically charged minerals help to maintain an electrical charge in the cells. The insides of cells are normally negatively charged relative to the outside. Special protein channels can open, allowing sodium in the cell, and making the cell positive. This is called depolarization. The cell becomes negative again when other protein channels open and let potassium flow out of the cell. The process of depolarization can signal the cell to perform certain functions, such as telling a muscle cell to contract.
Diseases
Low or high potassium can cause problems with the electrical functioning of the nerves and muscles, including the heart muscle, which in the worst case can stop the heart from beating effectively. Low potassium, or hypokalemia, is usually caused by diarrhea, vomiting, potassium loss in the urine, or an excessive shift of potassium into cells. High potassium, or hyperkalemia is usually caused by ineffective elimination from the kidneys, high ingestion or injection or release from the cells.
References
- American Heart Association: Potassium
- "Nutrition Concepts and Controversies"; Frances Sizer, Ellie Whitney; 11th Ed 2007
- "Physiology"; Linda S.Costanzo; 4th Ed 2008
- "Lehninger Principles of Biochemistry"; David L. Nelson and Michael M. Cox; 4th Ed 2004
- "Robbins and Cotran Pathologic Basis of Disease"; Vinay Kumar et al.; 8th Ed 2009
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