Potassium is a charged mineral called an electrolyte. It is an important chemical in the body because it helps all cells to function appropriately. It helps to maintain the normal electrical balance between the inside and outside of cells, allowing them to do work. If the balance is incorrect, such as by having low potassium in the body, more electrically active cells, such as the nerves and the heart, will be most affected.
Causes of Low Potassium
According to "Harrison's Principles of Internal Medicine" by Dr. Anthony Fauci, low potassium loss in the blood is typically from loss from the gastrointestinal tract, loss from the urinary tract, or a shift of the potassium from the blood to the inside of cells. Gastrointestinal losses can be from vomiting or diarrhea. Urinary losses are from the use of diuretics, or "water pills" that increase the amount of urine formed by the kidneys. High levels of aldosterone, the hormone made by the adrenal glands above the kidneys, also signal the kidneys to dispose of potassium. Certain conditions, such as the blood losing acid, by hyperventilation for example, can shift the potassium inside cells. It is also possible, but rare, to have low potassium from an inadequate diet.
Mechanism
According to "Hurst's The Heart" by Dr. Valentin Fulster, low potassium causes heart palpitations by disrupting normal electrical activity in the heart. The heart uses an electrical current to signal the heart muscle to contract in a coordinated manner. The electrical current is generated, maintained and spreads through the heart by the flow of charged minerals called electrolytes, including potassium, which has a positive charge in the body. Potassium helps the cell return to its normal electrical state after it has been electrically stimulated. Low potassium in the blood causes the heart cells to be electrically unstable. This leads to abnormal heart rhythms and uncoordinated contractions felt as heart palpitations.
Symptoms and Signs
Heart palpitations from low potassium may be without symptoms. They may also cause any one or more of the following symptoms: dizziness, lightheadedness, chest pain, fatigue and fluttering sensations in the chest. Low potassium may not be noticed. Symptoms may include fatigue, muscle weakness, muscle cramps and constipation.
Diagnosis
Diagnosis starts with a history -- which may include the patient's symptoms of low potassium and feeling heart palpitations, and the presence of risk factors such as diuretic use. Physical exam may reveal muscle weakness, changes to reflexes and hearing an abnormal heart rhythm. Laboratory investigation will include blood and possibly urine tests to measure the potassium and other chemicals. An electrocardiogram or ECG, or EKG, measures the electrical activity of the heart and may also be performed.
Treatment
The treatment of heart palpitations from low potassium involves raising the potassium and addressing the underlying causes. Potassium levels can be raised by taking oral or intravenous potassium supplements, requiring the prescription of a licensed health care professional. The cause will need to be determined and treated, such as diarrhea, vomiting or a problem with kidney function.
References
- "Harrison's Principles of Internal Medicine"; Anthony S. Fauci, et al; 2008
- "Hurst's the Heart"; Valentin Fuster, et al; 2007
