Potassium is an important nutrient and electrolyte — it helps muscles work, including those involved in breathing and keeping your heart beating.
But too much potassium in your system, known as hyperkalemia, can cause serious health problems. And people with kidney disease are more prone to developing hyperkalemia.
If you have kidney disease, here are five things you need to know about hyperkalemia in honor of National Kidney Month this March.
Potassium is naturally found in a wide variety of foods, including bananas, oranges, spinach, sweet potatoes, and avocados.
Normally, the body uses the potassium it needs and processes any excess potassium as waste. People with normal kidney function can typically eat a high potassium diet without issue.
If you have kidney disease, however, your kidneys may not remove any excess potassium from your body, resulting in hyperkalemia. Even a diet containing an average amount of potassium can cause hyperkalemia among people with kidney disease.
“The kidneys play a crucial role in maintaining a normal potassium balance by adjusting the amount of potassium excreted in the urine according to changes in potassium intake,” said Csaba P. Kovesdy, MD, a nephrologist and professor of medicine-nephrology at the University of Tennessee Health Science Center in Memphis, and member of the National Kidney Foundation.
“An increase in dietary potassium intake can only be compensated partially and temporarily by moving potassium into the cells,” added Kovesdy, “leaving the kidneys with the task of excreting the excess potassium and maintaining a normal potassium balance.”
“It is therefore not surprising that hyperkalemia is especially common in individuals with diminished kidney function,” explained Kovesdy, “especially if the kidney function deteriorates acutely (such as in acute kidney injury), or if the need to enhance potassium excretion arises rapidly (such as after a sudden increase in potassium intake).”
Up to half of those in predialysis stages of CKD may develop hyperkalemia. People with CKD who also have diabetes or cardiovascular disease are at especially high risk, as are those with advanced CKD, kidney transplant recipients, and those taking renin-angiotensin-aldosterone system (RAAS) inhibitors.
Kidney disease isn’t the only cause of hyperkalemia. High potassium can result from ingesting too much of the nutrient via food or supplements.
Other diseases, like diabetes, also may increase the risk of hyperkalemia.
Medications that cause the body to retain potassium, increase potassium supply, or contain potassium themselves, also can cause hyperkalemia.
For example, ACE inhibitors, used to treat high blood pressure and heart failure, block potassium excretion and increase the risk of hyperkalemia in people who take these drugs to treat these conditions.
If you have kidney disease, it’s entirely possible to also have hyperkalemia and not know it. Most people with high potassium have few or no symptoms.
Even when symptoms do arise — muscle weakness, numbness, tingling, nausea — they tend to be mild and hard to attribute to high potassium. These symptoms can develop slowly over time, and come and go.
If you experience heart palpitations, shortness of breath, chest pain, nausea, or vomiting, it could be a sign of a spike in potassium levels. Any sudden onset of hyperkalemia can be life threatening, so seek immediate medical care if you experience these symptoms.
Severe hyperkalemia can lead to symptoms like muscle weakness, paralysis, heart palpitations, and a burning or prickling sensation in the extremities.
The most serious symptom of hyperkalemia is cardiac arrhythmia, or an irregular heartbeat.
High potassium levels can interfere with the electrical signals involved in the function of the thick middle muscle layer of the heart, called the myocardium.
The resulting arrhythmias can lead to a heart attack — sometimes without warning, and sometimes fatal.
While hyperkalemia may be largely a hidden problem, it’s easy to diagnose.
A simple blood test can detect high levels of potassium in the blood. In fact, many people learn that they have hyperkalemia from the results of routine blood work or a basic metabolic panel that’s’ done for other health reasons.
Normal blood potassium levels range from around 3.6 to 5.0 millimoles/liter (mmol/L). If your blood potassium level is above this range, you may have hyperkalemia. Levels over 6.0 mmol/L are considered severe.
If you’re looking at your blood test results, blood potassium levels may be listed as “potassium,” “serum potassium,” or “K.”
“Potassium measurement is part of most routine laboratory tests that are typically performed in patients with kidney disease,” said Kovesdy. “More frequent testing is typically done in patients who have advanced stages of kidney disease, precisely because of the higher likelihood of the development of various metabolic abnormalities, of which hyperkalemia is one.”
If severe hyperkalemia is found, your doctor may also order an electrocardiogram (ECG) to assess the impact on your heart, and determine if emergency treatment is required.
The obvious way to treat hyperkalemia is to reduce the amount of potassium in your system.
The first step is to switch to a low potassium diet. Since individual potassium needs vary (you will still need to consume some), your healthcare provider or dietitian can help design an eating plan that’s right for your overall health and nutritional needs.
“The main problem with dietary restriction is not the difficulty of maintaining it,” said Kovesdy. “High potassium diets are cardioprotective, and restricting potassium intake represents a therapeutic compromise by asking patients to consume a less healthy diet to prevent the development of hyperkalemia.”
Hyperkalemia can also be treated with medical interventions.
Diuretics, or “water pills,” can be used to help flush excess potassium out of the body. Potassium binders, taken orally or rectally, may also be used to bind to potassium in the bowels, which helps remove excess potassium during the body’s natural process of digestion.
People with certain health conditions, including kidney disease, are at an increased risk of developing hyperkalemia. There’s a simple blood test that can help diagnose high potassium even if you’re not experiencing symptoms.
If you are diagnosed with hyperkalemia, it can be treated with dietary modifications and medical interventions. Taking steps to control high potassium can help reduce the risk of related medical emergencies.