18 July, 2011
Low Potassium & Abnormal EKG
Potassium is the most abundant cation, or positively charged ion, found inside human cells. Potassium is necessary for the proper functioning of skeletal muscles, kidneys and the heart. The effect of low blood potassium on the heart muscle can cause dysfunctional heart rhythm, which can manifest on the EKG. Certain diseases can result in increased loss of potassium from the body.
The electrocardiogram, or EKG, is a diagnostic tool used in interpreting electrical activity within the heart. Electrical activity in the heart depends on intact structures in the heart and proper amounts of electrolytes such as potassium and calcium. Before initiating diagnostic efforts, obtaining a baseline EKG of a patient prior to disease or heart-related complaint is extremely beneficial. However, reasonable interpretations of the EKG can be made by experienced physicians without a baseline EKG. The actual EKG procedure can be performed by trained technicians and nurses, as well as physicians.
Causes of Low Potassium
Hypokalemia, or low potassium, is defined as levels of potassium below 3.7 milliequivalents per liter, or mEq/L, of blood. Low blood potassium may result from the used dietary intake of potassium. Gastrointestinal losses, or loss of potassium from the digestive tract, is a common cause for low potassium; vomiting and diarrhea are gastrointestinal causes of low blood potassium. Hypokalemia may also result from increased urinary loss of potassium, such as from the use of diuretics, low blood magnesium and increase in pH, or reduced acidity, of blood.
Regulation of potassium is important in preventing adverse consequences associated with potassium imbalance. The kidneys are primarily involved with potassium excretion from the body. To adjust rates of potassium excretion, the kidneys must respond to hormonal influences in the body. Aldosterone -- a steroid hormone produced by the adrenal glands -- is the main hormones involved with potassium regulation; the release of aldosterone from the adrenal glands result in increased potassium excretion in the kidneys. The release of aldosterone is triggered by elevated levels of blood potassium, but release is inhibited when blood levels of potassium are low.
Treatment of Low Blood Potassium
The initial step in the treatment of low blood potassium is to identify and fix the cause; for example, if the cause of low blood potassium is due to prolonged vomiting, giving an antiemetic, or a drug that prevents vomiting, is the best initial step in the treatment of low blood potassium. Restoration of normal blood potassium levels can mostly be achieved with oral ingestion of potassium chloride, or KCl, tablets. According to "Davidson's Principles & Practice of Medicine," more severe cases of low blood potassium may be treated with intravenous, or IV, infusion of potassium into a vein. Restoration of normal potassium levels should correspond to positive changes in the EKG.
- Mayo Clinic: Low Potassium
- "Davidson's Principles & Practice of Medicine; Nicholas A. Boon; 2006
- "Harrison's Principles of Internal Medicine"; Dennis L. Kasper M.D., et al.; 2005
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