Your kidneys are in charge of regulating your potassium level. Potassium is a mineral that your body needs to function. It can be found in certain foods you eat, like bananas and potatoes. While a healthy level of potassium is essential for your body, too much potassium in the blood — a condition known as hyperkalemia — can be dangerous. Hyperkalemia can affect the heart, leading to heart rhythm abnormalities that require urgent medical care.

You can develop hyperkalemia if your kidneys aren’t able to filter out enough potassium from your blood, which can be true for some people with kidney disease. Chronic kidney disease is one of the risk factors for developing hyperkalemia, in addition to diabetes and heart failure.

Here, we explore how a high potassium level can impact the heart, including how it can cause serious complications.

How Is Potassium Related to the Heart?

Most potassium can be found inside the cells of the body, including heart cells. This is due to a natural process in which cells pump out three positively charged sodium ions (salt) and pull in two positively charged potassium ions. (Ions are atoms that have an electrical charge.) This exchange of sodium for potassium creates an electrical difference between the cell and what’s outside of it. During this energy-requiring process, the inside of the cell takes on a negative charge, which is especially important for the heart.

When potassium levels climb too high, the cells in the heart can send out electrical signals when they’re not supposed to. This can lead to an abnormal heart rhythm, called arrhythmia.

This give-and-take keeps cells negatively charged between heartbeats, which allows them to rest calmly. It’s important that heart cells are stable at rest, as this keeps them from sending out electrical signals at the wrong times. Having the right serum potassium level (potassium in the blood) allows the heart to beat in a regular rhythm.

How Does Hyperkalemia Affect the Heart?

A healthy potassium level helps to:

• Contract the heart muscle
• Control blood pressure
• Regulate the amount of fluid within cells

On the other hand, potassium levels that are too high or too low (called hypokalemia) can disturb the heart’s electrical balance. When potassium levels climb too high, the cells in the heart can send out electrical signals when they’re not supposed to. This can lead to cardiac arrhythmias (abnormal heart rhythms), which can be life-threatening and put you at risk for cardiac arrest.

How Does Hyperkalemia Affect People With Kidney Disease?

Hyperkalemia is estimated to affect only 2 percent to 3 percent of people in the U.S., but people with kidney disease are at a higher risk of developing it. Having chronic kidney disease (CKD) can triple your risk. In fact, more than half of those living with CKD who don’t require dialysis will develop hyperkalemia.

Other risk factors for hyperkalemia include:

• Acute kidney injury or other kidney issues
• Advanced age
• Alcohol use disorder
• Certain medications that can affect potassium levels, such as angiotensin-converting enzyme inhibitors (ACE inhibitors), angiotensin receptor blockers (ARBs), potassium-sparing diuretics, and renin-angiotensin-aldosterone system inhibitors
• Congestive heart failure and heart disease
• Diabetes
• Human immunodeficiency virus (HIV)
• Problems with the adrenal glands

More than half of those living with chronic kidney disease who don’t require dialysis will develop hyperkalemia.

If you have risk factors for hyperkalemia, your doctor may refer you to a nephrologist (a doctor who specializes in kidney conditions) who can monitor your potassium levels. Those with chronic kidney disease will likely already be monitored for hyperkalemia by their nephrologist, but you can always check in with your doctor to ask about your risk.

How Is Hyperkalemia Diagnosed?

Hyperkalemia doesn’t always cause symptoms, especially if it’s mild. Many people with hyperkalemia feel completely normal, while others may have general fatigue or gastrointestinal symptoms like diarrhea, nausea, vomiting, or abdominal pain. Since these symptoms have many possible causes and may come and go, the condition can be hard for doctors to diagnose.

In place of symptoms, a healthcare professional may use other information to diagnose you with hyperkalemia, including:

• Blood test results that show high serum potassium levels
• A history of kidney failure or problems with kidney function
• Electrocardiogram (ECG) results that show abnormal electrical activity
• Whether you’re taking any medications that can cause high potassium

Hyperkalemia is defined as a serum potassium level greater than 5.5 millimoles per liter. A healthy potassium level can fall anywhere between 3.5 and 5 millimoles per liter. It’s important to note that hyperkalemia doesn’t always show up on ECG results. Some people who have hyperkalemia may have normal, or only slightly abnormal, ECGs.

When To Seek Urgent Care

Hyperkalemia can turn severe quickly. Even mildly elevated potassium that’s not causing symptoms can worsen suddenly and lead to life-threatening complications. Severe hyperkalemia — potassium levels higher than 6.5 millimoles per liter — can cause cardiovascular problems.

Hyperkalemia can turn severe quickly. Even mildly elevated potassium that’s not causing symptoms can worsen suddenly and lead to life-threatening complications.

Seek emergency medical care if you develop symptoms of severe hyperkalemia, such as:

• Severe abdominal pain
• Chest pain
• Trouble breathing
• Heart palpitations
• A feeling that your heart is beating too fast, fluttering, or with an abnormal rhythm
• Severe muscle weakness or numbness in the arms or legs
• Weak pulse or other symptoms of a heart attack

How Is Hyperkalemia Treated?

Mild hyperkalemia often resolves with treatment and doesn’t cause any long-term complications. If your potassium level is only slightly elevated, your doctor may simply recommend changes to your diet or medications to bring it down. You may be asked to avoid or limit foods that are high in potassium, such as:

• Avocados
• Bananas
• Dried fruits
• Oranges and fresh orange juice
• Other fruits like kiwifruit, melons, nectarines, prunes, and raisins
• Pumpkin and winter squashes
• Tomatoes
• Vegetables like asparagus, potatoes, and cooked spinach

Very high levels of potassium or abnormal ECG results mean you need urgent medical care. The best treatment for you will depend on your potassium level, test results, and general health.

Treatment options for severe hyperkalemia may include:

• Dialysis — Helps the kidneys if they aren’t able to work well
• Diuretics (water pills) — Makes your body urinate more, which helps rid your body of extra potassium
• IV calcium — Protects your heart and other muscles
• IV glucose with insulin — Reduces the potassium level in your blood
• Medications — Prevent your body from absorbing potassium
• Potassium binders — Lower potassium levels by binding extra potassium to your stool
• Sodium bicarbonate — Helps regulate your body’s acidity level

According to the American Heart Association, people who have had heart failure and who have recurring episodes of hyperkalemia may need to take potassium binders regularly to help keep levels low.

Research has shown that hyperkalemia raises the risk of death from cardiac and other causes among people with cardiovascular disease. Regular monitoring for hyperkalemia paired with early treatment is essential for preventing serious complications.

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