Hyperkalemia: What Is High Potassium?

by Dr. Valerie Tan

Potassium is an essential mineral for the body and a type of electrolyte needed for its vital functions.

It is naturally present in many foods and is also available as a dietary supplement. It is present in all body tissues and is required for normal cell function because of its role in maintaining the proper fluid status inside the cells and for maintaining electrochemical gradients of the cells.

Most potassium is intracellular (inside the cells), amounting to approximately 30 times the extracellular (outside the cells) amount.

About 90% of ingested potassium is absorbed by the intestines, but it is primarily excreted in the urine. Some is excreted in the stool, and a very small amount is lost in sweat.

The kidneys control potassium excretion in response to changes in dietary intake, with potassium excretion increasing rapidly in healthy people after potassium consumption.

Healthy kidneys can adapt to variable potassium intake and will decrease excretion if there is a depletion of total body potassium.

There is a small amount of obligatory potassium loss regardless of body stores, and thus it is important to have an adequate potassium intake.

Hyperkalemia (high potassium level) is defined as a serum potassium level above the upper limits of normal, usually greater than 5.0 mEq/L to 5.5 mEq/L, with normal levels being 3.5-5.0 mEq/L.

While mild hyperkalemia is usually asymptomatic, high potassium levels may cause life-threatening cardiac arrhythmias (irregular heart rhythm), muscle weakness, or even paralysis.

Common Causes Of Hyperkalemia

High dietary intake – Potassium is primarily obtained through the diet. Common potassium-rich foods include meats, beans, tomatoes, potatoes, and fruits such as bananas, mangoes, papayas, and avocados. Increased dietary potassium intake is a very uncommon cause of hyperkalemia in people with normal kidney function, but it can be an important cause in those with kidney disease.

Use of potassium supplements, either as multivitamins or dietary salt substitutes such as those found in “low salt” or “no salt seasonings”, herbal supplements like noni, can produce hyperkalemia in a patient with impaired kidney function, especially if the eGFR falls to <30ml/min.

Medications that decrease potassium excretion – Certain medications can interfere with potassium excretion, especially in those with kidney disease, and lead to hyperkalemia.

Examples of these are angiotensin-converting enzyme (ACE) inhibitors such as lisinopril or benazepril; angiotensin receptor blockers (ARB) like losartan, olmesartan, and valsartan; mineralocorticoid receptor antagonists like finerenone; aldosterone antagonists like spironolactone; and nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen, naproxen, diclofenac, and celecoxib.

Medical conditions that decrease potassium excretion – Medical conditions such as diabetes, acute or chronic kidney disease, and genetic conditions that cause low levels or decreased response to the hormone aldosterone can cause hyperkalemia, especially when combined with high dietary intake and intake of certain medications such as those mentioned above.

Diabetics are at high risk for developing hyperkalemia due to a variety of factors. Insulin deficiency (as seen in Type 1 diabetes) or insulin resistance (as seen in Type 2 diabetes) causes decreased intracellular shift of potassium.

A healthy diabetic diet typically involves eating foods that are low in salt but are naturally high in potassium.

Medication regimens for diabetics typically involve the use of ACE inhibitors or ARBs to manage hypertension and decrease the risk and/or slow down kidney disease progression. For those who already have kidney disease, this can lead to further impaired potassium excretion.

Shifting of potassium from cells – Since potassium is primarily stored inside the cells, the majority of which are in the muscles, significant muscle injury, such as crush injury from accidents, medication side effects, or even excessive exercise, can cause the intracellular potassium to shift outside the cell, causing hyperkalemia.

Although mild hyperkalemia can be asymptomatic, severe hyperkalemia or a sudden, acute increase in potassium level can cause weakness, paralysis, and abnormal heart rhythms, leading to cardiac arrest.

Hyperkalemia is typically diagnosed on routine laboratory testing, and if it is only mild to moderate, it may be treated by medications that bind potassium so it can be excreted through the stool, making medication adjustments and limiting or completely avoiding high potassium foods. Severe and symptomatic hyperkalemia, even if mild to moderate, requires treatment in the emergency room.

Potassium is a vital mineral in the body, and it needs to be kept in a narrow normal range for the body to perform vital functions.

Abnormal levels, especially high levels or sudden increases, can have detrimental health effects, so discuss with your provider if you are concerned about your risk for hyperkalemia.

DR. VALERIA TAN is a board-certified Nephrologist and works at Hawaii Nephrologists, LLC.