Hyperkalaemia

Hyperkalaemia occurs when potassium levels in your blood rise too high, which can be life-threatening. While mild cases may not show symptoms, severe hyperkalaemia can cause dangerous heart problems that require urgent medical attention.

Table of contents

• What is hyperkalaemia?
• What causes hyperkalaemia?
• Signs and symptoms
• How is hyperkalaemia diagnosed?
• Treatment approaches
• Prevention and long-term management

What is hyperkalaemia?

Hyperkalaemia is a medical condition where the level of potassium in your blood becomes higher than normal. Potassium is a mineral that your body needs to work properly. It helps your heart beat regularly, your muscles move, and your nerves send signals throughout your body.^[2][3]

In healthy adults, normal potassium levels range from about 3.5 to 5.0 millimoles per liter (mmol/L) of blood. Hyperkalaemia is usually defined as a blood potassium level above 5.0 to 5.5 mmol/L. The condition can be classified as mild (5.5-6.0 mmol/L), moderate (6.1-7.0 mmol/L), or severe (above 7.0 mmol/L).^[3][4]

Your body normally gets potassium from the foods you eat. Your kidneys control how much potassium stays in your blood by removing extra amounts through your urine. When your kidneys work properly, they filter out surplus potassium fairly quickly. However, if your kidneys are damaged or not working well, potassium can build up in your blood to dangerous levels.^[11][16]

Hyperkalaemia is relatively rare in the general population, affecting about 2% to 3% of people. However, it is much more common in people with certain health conditions. Among those who are in hospital, between 1% and 2.5% have high potassium levels. People with chronic kidney disease (long-term kidney damage) are particularly at risk, with about 18% developing hyperkalaemia at some point.^[6][11]

What causes hyperkalaemia?

The most common cause of a high potassium reading is actually not true hyperkalaemia at all. This false reading, called pseudohyperkalaemia, happens when blood cells break apart during or after the blood sample is taken, releasing potassium into the sample. This can occur if the blood draw is done incorrectly, such as using a tourniquet too tightly or when the sample sits too long before being tested.^[2][6]

True hyperkalaemia most commonly develops because of kidney problems. Kidney disease is the leading cause because damaged kidneys cannot remove extra potassium from your blood as they should. Your kidneys need a hormone called aldosterone to know when to remove potassium. Diseases that reduce production of this hormone, such as Addison’s disease, can also lead to high potassium levels.^[5][11]

Many medications can cause or contribute to hyperkalaemia, especially in people who already have kidney problems. These include blood pressure medicines such as angiotensin-converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), and certain types of diuretics called potassium-sparing diuretics. Other medications that can raise potassium include some pain relievers (NSAIDs), blood thinners like heparin, and potassium supplements.^[5][9]

Eating too much potassium can contribute to hyperkalaemia, though this alone rarely causes problems in people with healthy kidneys. Foods high in potassium include dried fruits, seaweed, nuts, bananas, leafy greens, beans, potatoes, tomatoes, and certain fruit juices. Salt substitutes are also very high in potassium and should be avoided by people at risk.^[2][5]

Other health conditions can cause potassium to shift out of your cells and into your blood. These include uncontrolled diabetes, severe tissue damage from burns or injuries, breakdown of muscle tissue (called rhabdomyolysis), and breakdown of red blood cells. Very rarely, genetic disorders can cause high potassium levels, including conditions with complex names like pseudohypoaldosteronism.^[5][6][11]

Signs and symptoms

One of the dangers of hyperkalaemia is that mild cases often have no symptoms at all, or symptoms that are easy to overlook. You may not realize anything is wrong, which is why people often discover they have high potassium only through routine blood tests.^[2][3]

When mild symptoms do occur, they may include stomach pain, nausea, vomiting, or diarrhea. These symptoms can develop gradually over weeks or months, or they may come and go. Because these symptoms are common to many conditions, they do not necessarily point to hyperkalaemia.^[11][16]

Higher potassium levels can cause more serious symptoms. These include muscle pain, muscle weakness, numbness in your arms or legs, and feelings of tingling. At very high levels, potassium can cause paralysis or severe muscle weakness.^[2][6]

The most dangerous symptoms affect your heart. High potassium can cause your heart to beat irregularly, a condition called an arrhythmia. You may feel your heart racing, skipping beats, or fluttering (palpitations). You might also experience chest pain or shortness of breath. In the most severe cases, hyperkalaemia can cause your heart to stop beating altogether, leading to cardiac arrest and death.^[2][6][11]

The speed at which potassium levels rise is often more important than the actual number. Someone whose potassium has risen suddenly may have severe symptoms at lower levels than someone whose potassium has been gradually increasing over time. Symptoms typically appear when levels reach 6.5 to 7.0 mmol/L, but this can vary from person to person.^[2][10]

How is hyperkalaemia diagnosed?

Hyperkalaemia is diagnosed through a blood test that measures the amount of potassium in your blood. Because false high readings are common, any elevated result should be repeated to confirm true hyperkalaemia, especially if you do not have risk factors or symptoms.^[2][6]

If hyperkalaemia is confirmed, your doctor will likely order an electrocardiogram (ECG or EKG), which is a test that records the electrical activity of your heart. High potassium can cause specific changes in the heart’s electrical patterns that show up on the ECG. These changes can include peaked T waves, widened QRS complexes, and loss of P waves. However, a normal ECG does not rule out hyperkalaemia, and ECG changes do not always match the potassium level.^[3][7]

Your doctor will also test your kidney function to see how well your kidneys are working. This usually involves measuring levels of creatinine and other substances in your blood. Additional tests may include checking your urine for potassium levels and examining other blood values to understand what is causing the high potassium.^[2][8]

Treatment approaches

How aggressively hyperkalaemia is treated depends on how high your potassium level is, how quickly it has risen, whether you have symptoms, and what your ECG shows. All treatment aims to protect your heart, move potassium back into your cells, and remove excess potassium from your body.^[8][18]

Emergency treatment

If you have severe hyperkalaemia with dangerous ECG changes or symptoms, you need immediate treatment. The first step is to give calcium through a vein (intravenously). Calcium does not lower potassium levels, but it protects your heart muscle and reverses dangerous heart rhythm problems within minutes. Calcium gluconate or calcium chloride may be used.^[8][13]

Next, medications are given to quickly move potassium from your blood into your cells. These include insulin given with glucose (sugar) to prevent low blood sugar, inhaled medicines called beta-2 agonists such as salbutamol, or sodium bicarbonate in people who also have acidosis (too much acid in the blood). These treatments can lower potassium levels by about 0.5 to 1.0 mmol/L within 15 to 60 minutes.^[8][13][14]

Removing potassium from the body

While the above treatments provide short-term relief, they do not remove potassium from your body. To actually lower total body potassium, additional treatments are needed. These may include diuretics (water pills) such as furosemide, which help your kidneys remove more potassium through urine.^[8][14]

Potassium binders are medications that work by attaching to potassium in your digestive system, preventing your body from absorbing it. Newer agents called patiromer and sodium zirconium cyclosilicate are now preferred because they work well and have fewer serious side effects. An older medication called sodium polystyrene sulfonate (Kayexalate) is sometimes used but has been associated with serious intestinal problems.^[7][13]

For people with severe kidney disease or when other treatments do not work well enough, dialysis (also called hemodialysis) may be needed. Dialysis is a procedure that uses a machine to filter your blood and remove excess potassium. It is the most effective way to lower potassium levels and can remove large amounts quickly.^[8][13]

Prevention and long-term management

If you have had hyperkalaemia or are at risk for it, long-term management focuses on preventing future episodes. The first step is identifying and addressing the underlying cause. This might mean treating kidney disease, adjusting hormone levels, or managing diabetes better.^[8][17]

Your doctor will review all your medications and may need to stop or adjust those that raise potassium levels. However, do not stop taking any prescribed medication without talking to your doctor first, as some medicines that affect potassium are important for treating heart disease and other conditions.^[8][19]

Diet plays an important role in managing potassium levels. You may need to limit high-potassium foods such as bananas, oranges, tomatoes, potatoes, dried fruits, nuts, leafy greens, and beans. Lower-potassium alternatives include blueberries, raspberries, cucumbers, white or brown rice, pasta, and noodles. A dietitian can help you plan meals that keep your potassium intake in a safe range while still providing good nutrition.^[9][17]

Avoid salt substitutes, as most are very high in potassium. Also be aware that some herbal remedies and over-the-counter supplements can affect potassium levels. Always tell your doctor about any supplements or non-prescription products you are taking.^[9][19]

Regular blood tests are important to monitor your potassium levels, especially if you have kidney disease, heart disease, or take medications that affect potassium. People with cardiovascular disease or chronic kidney disease should have their potassium checked routinely, particularly if levels have been abnormal in the past.^[7][12]

If you exercise regularly, talk to your doctor about safe activity levels. Exercise causes muscles to release potassium temporarily, which is normally not a problem but could be risky if you have hyperkalaemia. Most people with well-controlled potassium can exercise safely with proper monitoring.^[14][21]

Stay well-hydrated unless your doctor has told you to limit fluids. Good hydration helps your kidneys work better at removing extra potassium. However, people with kidney, heart, or liver disease may need to limit fluid intake, so always follow your doctor’s specific recommendations.^[9][19]