Low Potassium (Hypokalemia) Overview
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Potassium is a mineral (electrolyte) in the body. Almost 98% of potassium is found inside the cells. Small changes in the level of potassium that is present outside the cells can have severe effects on the heart, nerves, and muscles.
Potassium is important to maintain several bodily functions:
- Muscles need potassium to contract.
- The heart muscle needs potassium to beat properly and regulate blood pressure.
The kidney is the main organ that controls the balance of potassium by removing excess potassium into the urine.
When potassium levels are low (hypokalemia), you can become weak as cellular processes are impaired.
- The normal potassium level is 3.5-5.0 mEq/L (mEq/L stand for milliequivalents per liter of blood and this is a unit measure used to evaluate the level). Low potassium is defined as a potassium level below 3.5 mEq/L.
- Almost one out of five people hospitalized in the United States has a low potassium level.
- People with eating disorders such as anorexia nervosa and bulimia, patients with AIDS, alcoholics, and those who have had bariatric surgery have a higher incidence of hypokalemia than others.
Low Potassium Causes
Low potassium can occur for many reasons. Use of water pills (diuretics), diarrhea, and chronic laxative abuse are the most common causes of low potassium levels.
Illness and other medications may also lower potassium levels. Woman and African-Americans are at higher risk of developing hypokalemia.
Other causes of hypokalemia include:
Loss of potassium through stomach and intestines
Effect of medicines
- Water pills (diuretics)
- Medicines used for asthma or emphysema (beta-adrenergic agonist drugs such as bronchodilators, steroids, or theophylline)
- Aminoglycosides (a type of antibiotic)
Shifting of potassium into and out of cells can lower the concentration of potassium measured in the blood.
- Use of insulin
- Certain metabolic states (such as alkalosis)
Decreased food intake or malnutrition
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Low Potassium Symptoms
Usually symptoms of low potassium are mild. At times the effects of low potassium can be vague. There may be more than one symptom involving the gastrointestinal (GI) tract, kidneys, muscles, heart, and nerves.
- Weakness, tiredness, or cramping in arm or leg muscles, sometimes severe enough to cause inability to move arms or legs due to weakness (much like a paralysis)
- Tingling or numbness
- Nausea or vomiting
- Abdominal cramping, bloating
- Palpitations (feeling your heart beat irregularly)
- Passing large amounts of urine or feeling thirsty most of the time
- Fainting due to low blood pressure
- Abnormal psychological behavior: depression, psychosis, delirium, confusion, or hallucinations.
When to Seek Medical Care for Low Potassium
If you are having symptoms of low potassium, call your doctor. If you have muscle cramps, weakness, palpitations, or feel faint and you are taking a diuretic (water pill), contact your healthcare professional or go to an urgent care facility or hospital emergency department immediately.
Without symptoms, you will not know you have low potassium levels until you have a routine blood test or an electrocardiogram (ECG, EKG).
Low Potassium Diagnosis
Sometimes the cause of low potassium is not clear. Your doctor may perform certain tests to rule out other conditions such as renal tubular acidosis, Cushing syndrome, and hypocalcemia.
- If an electrolyte imbalance is suspected, blood tests will be ordered check potassium levels, kidney function (BUN and creatinine), glucose, magnesium, calcium, and phosphorous if an electrolyte imbalance is suspected.
- Because low potassium is known to affect heart rhythms (arrhythmias), a doctor may order a digoxin (Lanoxin) level if the patient is taking a digitalis preparation.
- ECG or a heart tracing is done to detect electrical changes in the heart and certain types of irregular heart rhythms that may be caused by low potassium.
Low Potassium Self-Care at Home
If you are monitoring low potassium levels, avoid long, strenuous physical activities because loss of potassium occurs with sweating.
If dietary supplements, herbal supplements, diuretics (water pills), or laxatives are causing the low potassium symptoms, avoid taking these products and consult a doctor. Never stop taking a prescribed medication without first consulting your doctor.
Low Potassium Medical Treatment
Potassium replacement therapy will be directed by the type and severity of the patient's symptoms. Treatment begins after lab tests confirm the diagnosis.
People suspected of having severely low potassium need to be placed on a cardiac monitor and have an IV started.
Usually, those with mild or moderately low potassium levels (2.5-3.5 mEq/L), who have no symptoms, or who have only minor complaints only need to be treated with potassium given in pill or liquid form. This is preferred because it is easy to administer, safe, inexpensive, and readily absorbed from the gastrointestinal tract. Some preparations, or too high of a dose, may irritate the stomach and cause vomiting.
If cardiac arrhythmias or significant symptoms are present or if the potassium level is less than 2.5 mEq/L, IV potassium should be given. In this situation, admission or observation in the emergency department is indicated. Replacing potassium takes several hours as it must be administered very slowly intravenously to avoid serious heart problems and avoid irritating the blood vessel where the IV is placed.
For those with severely low potassium and symptoms, both IV potassium and oral medication are necessary.
- When potassium is used with medications such as ACE inhibitors, there is a risk of developing a high level of potassium.
- Potassium-sparing diuretics and potassium-containing salt substitutes can also result in high potassium levels.
Low Potassium Follow-up
Usually doctors recommend a certain dosage of potassium supplementation and arrange to have a repeat blood level taken 2-3 days later.
The doctor may consider switching to potassium-sparing diuretics (water pills) if the patient needs to continue taking diuretics for another condition.
Low Potassium Prevention
A change in diet may be recommended if the patient is likely to develop low potassium levels. Examples of foods high in potassium include:
Do not overuse diuretics (water pills), and never use someone else's medicines.
If the person is taking medication, ask the doctor how often electrolyte levels need to be checked.
Low Potassium Prognosis
The condition of low potassium is treatable. The reason for the low potassium must be sought out, or it will most likely reoccur. With the right therapy, there usually are no further problems.
A bagel 20 years ago was 3 inches in diameter and had 140 calories. How many calories do you think are in today's bagel?
Reviewed on 9/30/2019
Mount, David B. MD. "Clinical Manifestations and Treatment of Hypokalemia in Adults." UptoDate. Updated Jan 7, 2016.