Potassium is a mineral that works as an electrolyte and is involved in both electrical and cellular functions in the body. Potassium is the main positively charged ion within cells and is essential for the transmission of nerve impulses to muscles and organs, such as the heart. A potassium deficiency, also called hypokalemia, disrupts heart rhythm and rate and can become a serious medical condition.
Normal Potassium Levels
Normal potassium levels within the blood vary from 3.5 mEq/L to 5 mEq/L, according to "Human Biochemistry and Disease." Levels below 3.5 mEq/L are considered abnormal and termed hypokalemia. Americans rarely become potassium deficient by lack of it in their diet; rather, it is often the result of losing too much potassium in the urine or intestines from kidney disorders, diabetes, excessive vomiting or chronic diarrhea. Bulimia, laxative abuse, diuretics, prolonged use of medications and microbial infections can all lead to extended bouts of vomiting and diarrhea. Hypokalemia can be life-threatening and should always be treated by a doctor.
Symptoms of Hypokalemia
The symptoms of hypokalemia are dependent on the degree of the deficiency. According to "Professional Guide to Diseases," people do not usually experience symptoms until their blood potassium levels drop below 3 mEq/L. Initial symptoms include weak and achy muscles, fatigue, dry skin, hypertension and a slightly increased heart rate. As potassium levels continue to drop, cardiac arrhythmias develop, which are irregular heart beats and rhythms of the heart. Arrhythmias can be confirmed by electrocardiogram, or EKG, which document heart rate, rhythm and electrical activity. Cardiac arrhythmias can cause nausea, vomiting and excessive sweating. As hypokalemia progresses to critical levels and the nerve impulses are severely disrupted, heart rate becomes slower and erratic. Extreme muscle weakness or paralysis occurs, followed by congestive heart failure and death.
Slow Heart Rate
The heart normally beats between 60 and 100 times per minute, depending on physical exertion and time of day. A resting heart rate below 60 beats per minute is called bradycardia, while a resting heart rate above 100 beats per minute is termed tachycardia. Mild-to-moderate potassium deficiency often causes tachycardia because the nerve impulses to the heart are erratic and the body over-compensates due to the initial electrolyte imbalance. However, as the deficiency progresses, there is not enough potassium to initiate and sustain electrical nerve pulses, despite the body's safety mechanisms, and the heart rate slows down, weakens and eventually stops.
Reversing Potassium Deficiency
Although potassium deficiency is not usually caused by dietary factors, people in Third World countries or severely disadvantaged Americans might not get enough potassium in their diets. Good sources of potassium include fresh meats and fish, citrus fruits, bananas, potatoes with skin, spinach, broccoli and legumes. If underlying conditions are causing hypokalemia, such as diabetes or kidney disease, then they must first be treated. According to a 1992 Dutch study published in "Ugeskrit Laeger," serious potassium deficiency cannot be treated without correction of concomitant magnesium deficiency, which often co-exists with hypkalemia.
References
- "Human Biochemistry and Disease"; Gerald Litwack; 2008
- "Professional Guide to Diseases: Ninth Edition"; Springhouse Publishing; 2009
- University of Maryland Medical Center: Potassium Deficiency
- "American Dietetic Association Complete Food and Nutrition Guide"; American Dietetic Association; 2006
- "Ugeskrit Laeger"; Heart Rate Disorders in Potassium and Magnesium Deficiency; C. Tveskov et al; September 1992
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