Potassium is an electrolyte, or a mineral in the body that has an electric charge. When the potassium in the bloodstream reaches the kidneys, they reabsorb most of this mineral, trying to keep as much as possible in the bloodstream, available for use. The kidneys will try to excrete some potassium, however, if the level gets too high, which helps protect against some of the effects of high potassium on heart rate.
The potassium levels in the bloodstream should normally range from 3.5 mEq/L to 5.0 mEq/L. The medical term for an abnormally low level of potassium, or a level less than 3.5 mEq/L, is hypokalemia. People can develop a potassium deficiency as a result of several conditions, as explained in “Current Medical Diagnosis & Treatment” by Dr. Kerry Cho, assistant clinical professor of medicine at the University of California. It can be the result of long-term laxative abuse, due to diuretics, diarrhea, vomiting, dehydration, an adrenal gland disorder, certain tumors or a kidney disorder.
Symptoms of a Potassium Deficiency
The symptoms depend upon how much of a deficiency it is. People usually do not have any symptoms at all unless their potassium level is less than 3.0 mEq/L, Dr. Gary Singer, assistant professor of clinical medicine at the Washington University School of Medicine, explains in “Harrison’s Principles of Internal Medicine.” At that level a person can have weak muscles and muscle aches, and may also feel tired. If the potassium level falls even lower, the respiratory muscles can be affected and become weak, which can result in paralysis. The patient may also have problems with her heart.
The Heart and a Potassium Deficiency
People who have a low level of potassium will have an EKG, or an electrocardiogram, writes Dr. James Lewis III in “The Merck Manual for Healthcare Professionals.” An EKG will show the rhythm of the heart, the heart rate and any abnormality in its electrical activity. Hypokalemia usually does not have much of an effect on the heart unless the potassium level is below 3.0 mEq/L. Then the heart may contract too soon, there may be a problem sending signals within the heart, and the heart may beat too fast.
Tachycardia and a Potassium Deficiency
The heart normally beats 60 to 100 times every minute. Bradycardia describes a heart rate that is slower than 60 times a minute, while tachycardia is the medical term for a heart rate that beats faster than 100 times every minute. As explained in “The Merck Manual for Healthcare Professionals,” if the potassium deficiency is less than 3.0 mEq/L, people can develop tachycardia. Sometimes, the heart may not just beat fast, but develop a fast, irregular rhythm that will only get worse as the potassium levels decrease. If this continues, the affected person can develop a fast heart rate and fatal rhythm.
- Current Medical Diagnosis & Treatment 2011; Stephen McPhee, M.D., and Maxine Papadakis, M.D.
- Harrison’s Principles of Internal Medicine; Anthony Fauci, M.D., et al.
- The Merck Manual for Healthcare Professionals: Disorders of Potassium Concentrationrel="nofollow"
- stethoscope image by JASON WINTER from Fotolia.com
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