Are Your Potassium Levels Low? What to Know About Hypokalemia
Key takeaways:
Hypokalemia is the medical term for low potassium levels in the blood.
Common causes of hypokalemia are vomiting, diarrhea, certain medications, and conditions that affect the kidneys.
Hypokalemia is treated with oral or IV potassium supplementation. You may need magnesium supplementation to help correct your potassium levels, too.
Table of contents
Potassium is a critical electrolyte in your body. It provides electricity to your cells. It also helps maintain the acid-base balance in your body. This makes it necessary for many bodily functions, from contracting your muscles to helping your heart pump blood.
If your potassium levels get too low, problems can arise. In many cases, it doesn’t cause any symptoms. People usually find out they have hypokalemia after a routine blood test. In other cases, though, it can make people very sick and be life-threatening.
What is hypokalemia?
Hypokalemia means a low potassium level in the blood. Normal blood potassium levels are 3.5 mEq/L to 5 mEq/L. Hypokalemia is when the amount of potassium in the blood falls below 3.5 mEq/L. It can be categorized as:
Mild: 3 mEq/L to 3.5 mEq/L
Moderate: 2 mEq/L to 2.9 mEq/L
Severe: Less than 2 mEq/L
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Mild hypokalemia is quite common. It’s found in up to 14% of routine outpatient lab tests. This means a lot of people have mild hypokalemia without knowing it. More severe cases of hypokalemia tend to occur in someone who’s sick for other reasons.
Why is potassium important?
Potassium is one of the most important electrolytes in your body. All your cells need it to function properly. Potassium plays a critical role in muscle contraction, nerve conduction, and fluid balance. This means it’s important for regulating things like:
The heartbeat
Blood pressure
Muscle strength
Digestion
Kidney function
Blood sugar
What causes hypokalemia?
There are many causes of low potassium levels. And the problem isn’t usually from eating less foods with potassium. Most people in the U.S. get enough potassium from their diet. More often, the causes of hypokalemia are related to losses from the kidneys or gastrointestinal (GI) tract.
Kidney causes of hypokalemia
The potassium level in your body is mainly controlled by your kidneys. When potassium levels get too high, they pull the excess potassium from the blood into your urine so that you pee it out. When your potassium drops too low, the kidneys keep the potassium in the blood rather than putting any in the urine.
The following conditions can disrupt how your kidneys regulate potassium, leading to hypokalemia:
High blood sugar levels: When someone’s blood sugar level is high, the kidneys try to lower it by transferring the excess sugar into the urine. In order to do this, they also have to pull extra potassium into the urine.
Low magnesium levels: The kidneys regulate both potassium and magnesium levels in the blood. When someone has low magnesium, the kidneys work to preserve magnesium levels in the body. This can cause the kidneys to put more potassium into the urine than normal.
Chronic kidney disease: Most of the time, abnormal kidney function leads to high potassium levels. But sometimes dialysis treatment — which people need when their kidney function falls below a certain level — can remove too much potassium from the blood.
Endocrine disorders: Conditions like hyperaldosteronism or Cushing syndrome can affect the way kidneys handle potassium.
Genetic disorders: These are rare. But inherited conditions like Bartter syndrome, Gitelman syndrome, and Liddle syndrome can also increase the amount of potassium in the urine.
Explore supplements: Browse the types of supplements available to prevent and treat hypokalemia.
Pack your plate: Bananas aren’t the only good source of potassium. Learn more about 15 other potassium-rich foods.
Learn about the blood pressure connection: Getting more potassium could help lower your blood pressure.
Gastrointestinal causes of hypokalemia
The body can also lose potassium from the GI tract rather than from urine. This can happen to anyone with repeated vomiting or diarrhea. This is especially true for people who have:
Hyperemesis gravidarum (a severe form of morning sickness during pregnancy)
Eating disorders, especially bulimia nervosa
Cyclic vomiting (bouts of uncontrollable vomiting)
Intestinal conditions, like inflammatory bowel disease (IBS)
Laxative use
Medications that cause hypokalemia
There are several medications that can cause hypokalemia, for a variety of reasons. Common ones include:
Diuretics: These medications increase potassium loss by the way they increase urine production.
Antibiotics: Aminoglycoside antibiotics also increase the amount of potassium lost through the urine. And penicillin antibiotics can also cause hypokalemia.
Insulin: Insulin causes potassium to move from the blood to inside the cells. This means that the potassium blood level is lower, even if the potassium isn’t leaving the body.
Albuterol: Asthma inhalers like albuterol and other beta agonists have a similar effect as insulin. They cause potassium to shift from the blood to inside the cell.
Alcohol use disorder and hypokalemia
About half of people with chronic alcohol use will have hypokalemia. This happens for several different reasons. People with excessive alcohol consumption can develop hypokalemia from:
Poor diet: Heavy alcohol use is often linked with malnutrition and/or poor dietary intake, which can affect your potassium levels.
Magnesium deficiency: This is also caused by poor dietary intake. And, as explained above, low magnesium levels can cause the kidneys to pull out more potassium into the urine than normal.
Poor intestinal absorption, or diarrhea: Heavy alcohol use can prevent your gut from absorbing nutrients from food. Diarrhea from alcohol use can deplete these nutrients, too.
Nausea and vomiting: If someone’s alcohol use leads to vomiting, it will lower their potassium levels.
Hormone levels: Changes in hormone levels that happen with alcohol use can increase how much potassium is lost through the urine.
Alcohol withdrawal: Hormonal changes often occur when someone is in active alcohol withdrawal. This can cause more potassium to be passed through the urine.
What are the symptoms of hypokalemia?
Hypokalemia often doesn’t cause any symptoms until levels fall below 3 mEq/L. But the presence or severity of symptoms depends on more than just the actual number of the blood test. It also depends on how quickly someone’s level drops, as well as the underlying cause.
Symptoms of hypokalemia may include:
Muscle cramps
Constipation
Weakness
Fatigue
Dizziness, lightheadedness, or headaches
Shortness of breath
Feeling abnormal heartbeats or palpitations
What are the dangers of severe hypokalemia?
Although rare, severe cases of hypokalemia can be life-threatening. This is mainly because of the way it affects the heartbeat. Severe hypokalemia can lead to a number of abnormal heart rhythms, such as:
A slow heart rate (bradycardia)
Ventricular tachycardia, a very dangerous rhythm that leads to a rapid heart rate
Ventricular fibrillation, a rhythm that can lead to full cardiac arrest (although this is very rare)
Severe hypokalemia can also affect someone’s ability to breathe.This is because the impact on muscular contraction and nerve conduction affects someone’s ability to take a full breath.
How is hypokalemia diagnosed?
Hypokalemia is diagnosed with a blood test. The test measures several different electrolytes in your blood, along with your kidney function.
Many cases of milk hypokalemia are diagnosed when someone is getting blood tests for routine screening, or some other reason. But people who have known hypokalemia — or are at risk for hypokalemia — may get screening blood tests to monitor their potassium level.
How do you treat hypokalemia?
The treatment for hypokalemia usually requires supplements to get your levels back to normal. This can be done in a couple of different ways:
For mild to moderate hypokalemia, most people are prescribed oral potassium supplements.
Severe cases, especially when the heartbeat is affected, require urgent treatment in the hospital with IV (intravenous) potassium.
An important part of hypokalemia treatment is addressing the underlying cause. This means treatment may also include:
Magnesium supplements, if your magnesium level is low
Blood sugar management
Medications to help with vomiting or diarrhea
Lower doses of, or stopping, any medications that are causing hypokalemia
If you know you are prone to low potassium levels, a healthcare professional may advise you to increase your intake of potassium-containing foods. According to the World Health Organization, our daily intake of potassium should be at least 3,510 mg (you get about 10% of this in one banana).
How long does it take to recover from low potassium?
The amount of time it takes to normalize your potassium level depends on how low your potassium is, and what’s causing it.
If you’re taking oral supplements for hypokalemia, it may take several days to weeks to get your potassium level back up. In certain situations, you may need to stay on oral potassium pills long term to counterbalance your body’s loss of potassium.
When someone has a severe case of hypokalemia, IV treatment will increase their levels faster than pills. It usually takes only 1 to 2 days.
Frequently asked questions
Although it’s very rare, severe cases of hypokalemia can be fatal. This is because potassium helps regulate the heartbeat. So when the potassium level is critically low, the heart cannot beat normally. It can lead to dangerous heart rhythms like ventricular tachycardia or ventricular fibrillation, which can lead to cardiac arrest.
Most of the time, low potassium isn’t a sign of cancer. Low potassium is a common condition, and there are other much more likely causes than cancer. But people who are living with cancer may also have low potassium if the cancer (or cancer treatment) is causing things like:
Poor appetite and malnutrition
Vomiting or diarrhea
Abnormal kidney function
Low potassium doesn’t cause seizures.
The bottom line
Hypokalemia means your potassium level is low. This can affect important body functions like your muscles and heart. Mild hypokalemia is relatively common, and most of the time this doesn’t cause any symptoms. It can easily be treated with increased potassium intake through food or supplements. More severe hypokalemia may require a hospital stay for treatment with IV potassium. This is to avoid any serious heart complications. Fortunately, though, these cases are more rare.
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References
Baj, J., et al. (2020). Magnesium, calcium, potassium, sodium, phosphorus, selenium, zinc, and chromium levels in alcohol use disorder: A review. Journal of Clinical Medicine.
Kardalas, E., et al. (2018). Hypokalemia: A clinical update. Endocrine Connections.
National Kidney Foundation. (2023). Potassium.
Office of Dietary Supplements. (2022). Potassium: Fact sheet for health professionals. National Institutes of Health.
Rehan, H. S., et al. (2019). Antimicrobial agents-induced hypokalemia: A possible causality association. Indian Journal of Critical Care Medicine.
World Health Organization. (2013). WHO issues new guidance on dietary salt and potassium.
