Potassium is a mineral that is essential to life. In the body, it exists mostly as an electrolyte, which is an electrically charged mineral. All cells of the body have an electrical charge and potassium helps to maintain this charge. When potassium gets out of its normal range, the electrical charge in cells is disrupted, causing problems with cells, especially the nerves, heart and muscles.
Potassium
Potassium levels are higher inside of cells than outside, in contrast to sodium, which is higher outside of cells. This separation of electrolytes helps to maintain the electrical charge in cells. The charge is used for energy transfer and signaling, such as signaling muscles to contract, the heart to beat or insulin to be released from the pancreas. Potassium levels shift in and out of the cell to change the charge transiently, then return to baseline levels.
Range
Potassium levels in blood are measured as part of a blood test called a metabolic panel that measures this electrolyte, along with a number of others. The normal range of potassium was determined by measuring potassium from many healthy people and determining what the average potassium level is in those people, and how much it deviates from the average value. So, there is not one number that represents normal potassium. A given person may have a lower or higher potassium compared to another person. However, the farther the potassium level is from the average, the more likely it is abnormal.
Measurement
The normal, or average, range for potassium is considered by most labs to be 3.5 to 5.0 mEq/L. The measurement can become erroneous for several reasons. For example, if the sample is drawn too rapidly, or a person is clenching and relaxing their fists too much, the red blood cells can break open, releasing potassium and making the reading falsely high. Hyperventilation, as from anxiety, can lower the potassium level.
Conditions
There are many conditions and drugs that can decrease or elevate the potassium. Both can be dangerous. Decreased potassium is called hypokalemia and is caused generally by loss from the urinary tract, GI tract, skin, inadequate intake and the shifting of potassium from blood into cells. Excessive potassium is called hyperkalemia. It is broadly caused by kidney problems affecting elimination, excessive intake and release from cells.
References
- "Lehninger Principles of Biochemistry"; David L. Nelson and Michael M. Cox; 4th Ed 2004
- "Harrison's Principles of Internal Medicine"; Anthony S Fauci et al; 17th Ed 2008
- "Henry's Clinical Diagnosis and Management by Laboratory Methods"; Richard A. McPherson and Matthew R. Pincus; 21st Ed 2006
Member Comments