If you are a fairly healthy individual, you probably go about your daily activities without having to pay much attention to your muscle or nerve function. Yet the delicate process through which your muscles and nerves work requires specific levels of substances called electrolytes. Potassium is one of those key substances. Its levels usually rise above normal because of simultaneous problems, including excessive intake; kidney problems and certain drugs.
In an adult, blood potassium levels normally range from 3.5 to 5 milli-equivalents per liter, or mEq/L. Thus, hyperkalemia, the medical term for high blood potassium, refers to levels above 5.5 mEq/L. However, Florida-based physician and professor of Nephrology Richard Preston notes that cardiac and neuromuscular signs and symptoms usually manifest when your levels exceed 6.5 mEq/L. At that point, hyperkalemia becomes a medical emergency.
True Potassium Elevation
Normally, when your potassium intake increases, your kidneys try to get rid of the excess in order to maintain healthy ranges. When this does not happen and blood potassium remains high as a result of true excess body potassium, it's usually because of defective potassium excretion, says Preston. Your body may not be able to excrete excess potassium as a result of kidney disease, aldosterone deficiency or unresponsiveness to aldosterone signals. Aldosterone is the main hormone that regulates salt, water and electrolyte balance in the body.
Potassium test values can be falsely elevated. Physicians refer to this phenomenon as "pseudohyperkalemia." Possible causes include lab error, repeated fist clenching during the blood drawing process, and a viral infection called mononucleosis. According to Preston, excessive numbers of platelets or white blood cells in your blood can also lead to high potassium values. More rarely, high values may result from a hereditary condition known as "familial pseudohyperkalemia," which causes potassium to leak out of red blood cells.
Although, for practical purposes, a potassium test checks potassium levels in your blood, most of your body's potassium reserves are actually inside your cells. Thus, blood potassium can rise as a result of cells releasing large amounts of potassium, says Preston. Physicians name this phenomenon "redistribution hyperkalemia." Possible causes include: hydrogen ion imbalances; a class of drugs called beta adrenergic blocking agents; massive overdose with the drug digitalis; insulin deficiency; severe burns and severe infections.
A number of drugs can cause or aggravate hyperkalemia, notes physician Maxine Papadakis. They do so, either by inhibiting potassium excretion, adding potassium to your body, promoting potassium shifts, or by interfering with aldosterone function. A few examples among many include the class of pain killers known as nonsteroidal anti-inflammatory drugs, heparin, ACE inhibitors and some diuretics.
Symptoms & Treatment
A small elevation in blood potassium does not usually produce symptoms, says the Merck Manual. However, moderate and severe hyperkalemia can cause palpitations, lethargy, muscle weakness, paralysis, a slow heart rate, confusion and even respiratory failure. According to First Consult, the emergency treatment of severe hyperkalemia initially involves in-hospital injections of calcium gluconate followed by infusions of insulin and glucose. For mild cases, taking less potassium and avoiding any drug that prevents your body from excreting potassium is usually sufficient.
- "Quick Answers to Medical Diagnosis and Therapy;" Maxine A. Papadakis, M.D. et al.; 2010
- "First Consult: Hyperkalemia"; Martin; Ankush Gulati, M.D. et al.
- Merck Manual of Medical Information: Potassium
- "Acid-Base, Fluids and Electrolytes"; Richard A. Preston, M.D.; 2002