Potassium is an essential dietary mineral and electrolyte. As a mineral, potassium is required for proper metabolism of carbohydrates. As an electrolyte, or ion, potassium is able to conduct electricity, maintaining a current across the membrane of your cells. Potassium is the major positively-charged ion inside your cells, where concentrations are 30 times what they are in the extracellular fluid. The maintenance of potassium balance is essential for the normal function of many tissues, and excessive potassium levels, known as hyperkalemia, pose significant health risks.
High Potassium Causes
Hormones, drugs and various pathologic states alter the distribution of potassium across cell membranes and, as a consequence, can cause the extracellular concentration to go up. It is the potassium levels outside of cells that are measured by blood tests. The normal range for blood potassium is 3.5 to 5.1 mEq/L. Excessive dietary intake of potassium generally does not cause hyperkalemia, except in person taking medications that cause the body to retain potassium. These include certain types of blood pressure medications.
Other Causes
Hyperkalemia is most often seen in persons who suffer kidney disease. The kidneys play a central role in potassium homeostasis and in individuals with compromised renal function, the kidneys are unable to excrete potassium and blood levels rise. Additionally, conditions that lead to the release of stored potassium into the blood can cause levels to rise. These include vigorous exercise, infection and severe burns.
Common Symptoms
An elevated potassium concentration in the blood interferes with normal muscle function to produce muscle weakness and tingling of the hands and feet. In extreme cases, a type of paralysis known as flaccid paralysis can occur. This type of paralysis is characterized by muscles that are soft and limp, as opposed to spastic paralysis, in which they are stiff. Distension of your stomach as well as diarrhea may also occur.
Serious Effects
High blood potassium levels also affect the heart and if levels exceed 6.5 mEq/L, the consequences can be serious if not fatal. Initial changes are seen on electrocardiography and manifest as characteristic wave patterns. Peaked T waves and widening of QRS complexes may be seen. These ECG changes may not be accompanied by symptoms. In cases of severe hyperkalemia, an abnormal heart rhythm may develop. This condition, known as cardiac arrhythmia, can result in cardiac arrest.
References
- "Current Medical Diagnosis and Treatment"; Stephen J. McPhee; 2011
- "Physiology"; Linda S. Costanzo; 2009
- Linus Pauling Institute: Micronutrient Information Center: Potassium
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