Common Causes of Hyperkalemia

Hyperkalemia can happen for several reasons. For some people, the main issue is reduced kidney function. For others, the cause may be related to medications, supplements, diabetes, hormone changes, injury, or a combination of factors.

This FKP Kidney Health article explains the common causes of hyperkalemia, why kidney function matters, how medications can affect potassium balance, and when high potassium may require urgent medical attention.

What Is Hyperkalemia?

Hyperkalemia means the potassium level measured in serum or plasma on a blood test is higher than expected. Potassium is an electrolyte that helps support electrical signaling in the body. Your nerves, muscles, and heart all depend on potassium to work properly.

Most potassium is inside the body’s cells. Only a small amount is normally found in the bloodstream. Because the blood potassium level must stay within a safe range, even a modest increase can matter, especially if potassium rises quickly.

Many laboratories consider a typical blood potassium range to be about 3.5 to 5.0 mEq/L, but the exact reference range can vary by lab. For potassium, mEq/L and mmol/L are numerically equivalent. Your healthcare provider will interpret your result based on your kidney function, medications, symptoms, EKG findings when needed, and overall health.

The potassium number matters, but the speed of the increase, the patient’s kidney function, symptoms, and heart rhythm findings can be just as important as the number itself.

An article published by National Library of Medicine notes that “massive blood transfusions can significantly elevate serum potassium levels.”

Many patients have more than one contributing factor. For example, a person with CKD who takes an ACE inhibitor and uses a potassium-based salt substitute may have a higher risk than someone with only one of those factors.

Why the Kidneys Matter in Potassium Balance

The kidneys help control potassium by filtering blood and removing extra potassium through the urine. When the kidneys are working well, they help balance potassium intake with potassium removal.

When kidney function is reduced, the kidneys may not remove potassium efficiently. This can allow potassium to build up in the bloodstream.

This is why hyperkalemia is more common in people with:

• Chronic kidney disease (CKD)
• Acute kidney injury (AKI)
• Advanced kidney disease
• Diabetes-related kidney disease
• Heart failure or conditions that affect blood flow to the kidneys
• Reduced urine output
• Certain medication combinations

Importantly, high potassium does not usually mean that potassium itself caused kidney disease. More often, it means the kidneys, hormones, medications, or other body systems are not keeping potassium in balance.

Kidney Dysfunction as a Cause of Hyperkalemia

Chronic Kidney Disease (CKD)

In CKD, kidney function declines over time. In earlier stages, the kidneys may still compensate and keep potassium in a safe range. As CKD becomes more advanced, the risk of hyperkalemia increases because the kidneys may not be able to remove enough potassium.

Patients with CKD may need periodic blood testing to monitor potassium, kidney function, acid-base balance, and other electrolytes.

Acute Kidney Injury (AKI)

AKI is a sudden decline in kidney function. It may occur during severe illness, dehydration, infection, medication-related kidney stress, low blood pressure, or other medical events.

Because AKI can reduce the kidneys’ ability to remove potassium, potassium may rise quickly. This is one reason doctors often monitor potassium closely in hospitalized or medically fragile patients.

Medications That Can Raise Potassium

Some medications can increase potassium by reducing how much potassium the kidneys remove, changing hormone signals, or affecting kidney blood flow. These medications may still be necessary and beneficial, so patients should not stop them on their own.

Common medication-related contributors include:

• Angiotensin-Converting Enzyme (ACE) Inhibitors and Angiotensin Receptor Blockers (ARBs): These foundational medications may protect the heart and slow CKD progression in selected patients. However, by reducing activity in the renin-angiotensin-aldosterone system (RAAS), they can lower aldosterone signaling. Aldosterone helps tell the kidneys to remove potassium, so reduced aldosterone activity may lead to potassium retention in the blood.
• Mineralocorticoid Receptor Antagonists (MRAs): These medications block aldosterone’s effect. Spironolactone and eplerenone are steroidal MRAs often used for heart failure, resistant hypertension, or hyperaldosteronism, but they can raise potassium, especially when kidney function is low. Finerenone is a nonsteroidal MRA used in selected patients with CKD associated with type 2 diabetes and in some adults with heart failure with left ventricular ejection fraction of 40% or higher. Like other MRAs, finerenone can raise potassium and requires potassium and kidney function monitoring.
• Potassium-Sparing Diuretics: These medications help the body remove sodium and water while retaining potassium. This can be helpful in some conditions but may raise potassium too much in higher-risk patients.
• Non-Steroidal Anti-Inflammatory Drugs (NSAIDs): NSAIDs, such as ibuprofen or naproxen, can reduce kidney blood flow and affect prostaglandin activity. This may reduce renin and aldosterone signaling, impair kidney potassium excretion, and increase hyperkalemia risk, especially in people with CKD, dehydration, heart failure, or RAAS-blocking medications.
• Beta Blockers: These medications can contribute to higher potassium in some patients by reducing potassium movement into cells and affecting kidney-related hormone signaling. The risk is usually greater when other risk factors are present.
• Heparin: Heparin can reduce aldosterone production in some patients, which may impair potassium excretion.
• Tacrolimus and Cyclosporine: These immunosuppressive medications can affect kidney potassium handling and may raise potassium in susceptible patients.
• Trimethoprim-Sulfamethoxazole: This antibiotic combination can reduce potassium excretion in a way that may resemble potassium-sparing diuretic effects, especially in people with CKD or those taking RAAS-blocking medications.

The risk is higher when multiple potassium-raising factors are present, such as CKD, diabetes, heart failure, dehydration, potassium supplements, advanced age, or combined medication effects.

A Safety Note About ACE Inhibitors, ARBs, and Kidney Protection

ACE inhibitors and ARBs can raise potassium in some patients, but they can also be important for protecting the heart and kidneys. If potassium rises while you are taking one of these medications, your healthcare provider may review your diet, supplements, over-the-counter medications, kidney function, and other prescriptions.

In many patients, clinicians first look for ways to manage potassium safely while preserving kidney- or heart-protective therapy when appropriate. This may involve closer monitoring, changing a dose, treating contributing factors, using a potassium-lowering treatment, or considering other options.

Do not stop ACE inhibitors, ARBs, MRAs, or other prescribed medications unless your healthcare provider tells you to.

Potassium Supplements, Salt Substitutes, and Diet

Potassium in food is not automatically harmful. Many potassium-rich foods, including fruits, vegetables, beans, and other plant-based foods, can be part of a heart-healthy diet.

However, people with CKD or other risk factors may not be able to remove extra potassium well. Hyperkalemia risk can increase with:

• Potassium supplements
• Potassium-containing salt substitutes
• High-potassium electrolyte drinks
• Potassium additives in processed foods
• Large amounts of high-potassium foods in a short period
• Combining high potassium intake with reduced kidney function or potassium-raising medications

A key safety point is that a normal diet is not the same as taking potassium in concentrated forms. Potassium supplements, electrolyte drinks, and potassium chloride salt substitutes can add a large potassium load quickly.

Patients can also check ingredient labels for the word “potassium”, including ingredients such as potassium chloride, potassium phosphate, potassium citrate, or other potassium-based additives.

Modern kidney nutrition is individualized. A strict low-potassium diet is not appropriate for everyone, and unnecessary avoidance of fruits and vegetables may reduce the benefits of a healthy eating pattern. For many patients, the first step is not to fear all plant foods, but to identify the most relevant potassium sources, avoid potassium-based salt substitutes unless approved, limit highly processed foods with potassium additives, and work with a renal dietitian when needed.

Patients with kidney disease should ask their healthcare provider or renal dietitian before using salt substitutes, potassium supplements, electrolyte drinks, or major diet changes.

Diabetes, DKA, and Hyperkalemia

Diabetes can raise hyperkalemia risk in more than one way.

First, diabetes can damage the kidneys over time, making it harder for the kidneys to remove potassium. Second, insulin helps move potassium from the bloodstream into the body’s cells. When insulin is very low or blood sugar is severely uncontrolled, potassium can shift out of cells and accumulate in the bloodstream.

This can occur in serious conditions such as diabetic ketoacidosis (DKA). In DKA, the blood potassium level may be high even when the body’s total potassium stores are low. Treatment with insulin and fluids can shift potassium back into cells, so potassium must be monitored closely in medical care.

This is one reason DKA should never be self-managed at home.

Other Medical Causes of Hyperkalemia

Hyperkalemia can also happen when potassium moves from inside cells into the bloodstream or when hormone signals that help remove potassium are disrupted.

Possible causes include:

• Metabolic acidosis: Acid-base changes can shift potassium out of cells and may worsen hyperkalemia.
• Adrenal gland disorders: Low aldosterone activity can reduce potassium excretion by the kidneys.
• Severe injury, burns, crush injuries, or major surgery: Damaged cells can release potassium into the bloodstream.
• Rhabdomyolysis: Severe muscle breakdown can release potassium and other cell contents into the blood.
• Tumor lysis syndrome: Rapid breakdown of cancer cells can release potassium and other electrolytes into the bloodstream.
• Massive or rapid blood transfusion: This can add potassium load and is usually managed in closely monitored hospital settings.

These causes are not always present alone. Hyperkalemia often results from more than one factor at the same time.

Could a High Potassium Result Be Incorrect?

Pseudohyperkalemia is an artificial elevation of serum potassium that occurs during or after the blood draw, rather than from a true increase in potassium inside the body.

Possible reasons include:

• Red blood cells breaking during or after the blood draw
• Blood sample handling issues
• Repeated fist clenching during the blood draw
• Very high platelet or white blood cell counts in certain blood disorders
• Delays or mechanical stress during sample processing

A repeat test may be needed, but a high potassium result should never be dismissed without medical review. If the result does not fit your symptoms, kidney function, or medical history, your healthcare provider may repeat the blood test or order additional testing.

Patients should not ignore a high potassium result, but they also should not panic or self-treat without medical guidance.

When High Potassium Is an Emergency

High potassium may require urgent treatment if it is severe, rising quickly, associated with kidney failure, accompanied by EKG changes, or causing symptoms.

Seek urgent medical care if you have been told your potassium is high and you develop:

• Chest pain
• Shortness of breath
• Fainting
• Severe weakness
• Paralysis
• A fast, pounding, slow, or irregular heartbeat
• Confusion or feeling suddenly very unwell

Sudden or severe hyperkalemia can affect the heart’s electrical rhythm and may be life-threatening.

Symptoms of Hyperkalemia

Many people with mild or moderate hyperkalemia have few or no symptoms. However, the absence of symptoms does not mean high potassium is safe. In some cases, the first serious sign may be a dangerous heart rhythm problem.

Possible symptoms include:

• Muscle weakness
• Numbness or tingling
• Nausea
• Fatigue
• Palpitations or an irregular heartbeat
• Shortness of breath
• Chest discomfort
• Severe weakness or paralysis

Because symptoms can be absent or nonspecific, blood testing is especially important for people at higher risk.

How Doctors Evaluate the Cause of Hyperkalemia

To understand why potassium is high, your healthcare provider may review:

• Your potassium level and whether it is rising or stable
• Whether the result should be repeated
• Kidney function tests, including creatinine and eGFR
• Your medication list, including over-the-counter drugs
• Supplements, salt substitutes, electrolyte drinks, and nutrition products
• Diabetes control
• Urine output
• Recent illness, dehydration, surgery, injury, or hospitalization
• Whether an EKG is needed to evaluate heart rhythm
• Whether acidosis or hormone-related causes may be contributing

The goal is not only to lower potassium, but also to understand why it increased.

Prevention and Management

Preventing hyperkalemia depends on your individual risk factors. Common strategies may include:

• Regular blood testing if you have CKD, diabetes, heart failure, or medication-related risk
• Monitoring potassium after starting or changing certain medications
• Reviewing prescription medications, over-the-counter medications, and supplements
• Avoiding potassium supplements unless prescribed
• Asking before using potassium-based salt substitutes
• Limiting highly processed foods that contain potassium additives when recommended
• Following an individualized kidney-friendly diet when needed
• Managing diabetes, blood pressure, and kidney disease
• Reporting new symptoms promptly

Treatment depends on how high the potassium is, how quickly it rose, whether symptoms or EKG changes are present, and what caused it. Treatment may involve medication changes, potassium binders, diuretics when appropriate, dietary adjustments, or urgent hospital treatment in severe cases. In advanced kidney failure, dialysis may be needed in certain situations.

Working With Your Care Team

Hyperkalemia is often manageable when it is recognized and monitored appropriately. If you have kidney disease or are taking medications that can affect potassium, regular monitoring helps your care team detect changes early.

At Florida Kidney Physicians, we encourage patients to ask questions about their lab results, medication list, diet, and kidney health plan. Understanding the cause of high potassium can help you and your healthcare team choose the safest next steps.

FAQs

What are the most common causes of hyperkalemia?

The most common causes of hyperkalemia include reduced kidney potassium removal from chronic kidney disease or acute kidney injury, medications that affect aldosterone or kidney blood flow, potassium supplements or salt substitutes, uncontrolled diabetes or DKA, acidosis, and potassium release from damaged cells.

What potassium level is considered dangerous?

Potassium levels around 6.0 mEq/L or higher are usually more concerning, and levels around 6.5 mEq/L or higher are often treated as a severe range in many clinical frameworks. Any potassium level may be urgent if it rises quickly, causes symptoms, occurs with AKI, or is associated with EKG changes.

Can ibuprofen or naproxen raise potassium?

Yes. NSAIDs such as ibuprofen or naproxen can contribute to high potassium in some patients, especially people with CKD, dehydration, heart failure, or RAAS-blocking medications. Ask your healthcare provider before using NSAIDs regularly.

Are salt substitutes safe if I have kidney disease?

Some salt substitutes contain potassium chloride and may raise potassium. People with CKD, reduced kidney function, or a history of potassium problems should ask their healthcare provider before using salt substitutes.

Can blood pressure medications cause high potassium?

Yes. ACE inhibitors, ARBs, MRAs, and related medications can raise potassium in some patients by reducing aldosterone signaling or blocking aldosterone’s effect. However, these medications may also protect the heart and kidneys, so they should not be stopped unless a healthcare provider recommends it.

Why would my doctor repeat a potassium test?

A repeat test may help confirm whether potassium is truly high or whether the result may have been affected by the blood draw or sample handling. A high potassium result should still be reviewed by a healthcare provider.

Can diabetes cause hyperkalemia?

Yes. Diabetes can contribute to hyperkalemia by damaging the kidneys over time and, in severe uncontrolled cases such as DKA, by causing potassium to shift from inside cells into the bloodstream. In DKA, blood potassium may be high even when total body potassium is low.

Should everyone with CKD avoid high-potassium fruits and vegetables?

No. Diet should be individualized. Many plant-based foods can be part of a healthy kidney and heart-protective eating pattern. Patients with persistent or severe hyperkalemia may need potassium moderation, but unnecessary avoidance of fruits and vegetables can make the diet less healthy and harder to follow.

When should high potassium be treated as an emergency?

High potassium may be an emergency if it is severe, rising quickly, associated with AKI or kidney failure, accompanied by EKG changes, or causing symptoms such as chest pain, fainting, shortness of breath, severe weakness, paralysis, or an irregular heartbeat.