What are the causes of hyperkalemia?

Hyperkalemia Causes

Hyperkalemia results from three fundamental mechanisms: decreased renal potassium excretion (the dominant cause in clinical practice), transcellular shift of potassium out of cells, or excessive potassium intake—with impaired renal excretion being the most important mechanism in sustained hyperkalemia. 1, 2

Decreased Renal Potassium Excretion

This is the primary mechanism underlying most cases of clinically significant hyperkalemia.

• Chronic kidney disease is the most common cause, with hyperkalemia incidence increasing dramatically as eGFR declines—occurring in up to 73% of patients with advanced CKD (stage 4-5). 1, 3
• Hyperkalemia risk becomes substantial once eGFR falls below 60 mL/min/1.73 m² in patients on RAAS inhibitors, and is generally increased when eGFR is less than 15 mL/min/1.73 m². 1
• Acute kidney injury is frequently accompanied by acute pancreatitis or hepatic failure, and was present in all cases of hyperkalemia-induced cardiac arrest in one retrospective analysis. 1
• The kidneys are the primary regulators of potassium homeostasis; impaired renal excretion leads to sustained hyperkalemia, whereas cell shift causes only transient elevations. 2, 4

Mechanisms of Impaired Renal Excretion

• Reduced sodium delivery to the distal nephron limits potassium secretion. 2
• Decreased mineralocorticoid (aldosterone) level or activity impairs distal tubular potassium excretion. 2
• Abnormalities in the cortical collecting duct directly impair potassium secretion. 2
• In many cases, all three of these perturbations are present simultaneously. 2

Drug-Induced Hyperkalemia

Medications represent the most important iatrogenic cause of hyperkalemia in everyday clinical practice, particularly RAAS inhibitors.

RAAS Inhibitors

• ACE inhibitors, ARBs, and mineralocorticoid receptor antagonists cause hyperkalemia by lowering aldosterone activity and reducing renal potassium excretion. 1
• In hypertensive patients without risk factors, the incidence of hyperkalemia with RAAS inhibitor monotherapy is <2%, increases to 5% with dual RAAS inhibition, and reaches 5-10% when dual therapy is administered in patients with heart failure or CKD. 5
• Up to 40% of heart failure patients and 5-10% of those on combination RAAS therapy develop hyperkalemia. 1
• Up to one-third of NYHA Class II-IV heart failure patients starting an MRA develop hyperkalemia (>5.0 mEq/L) over 2 years. 5
• In the real-world setting, the incidence of hyperkalemia can be as high as 50% in unselected populations receiving RAAS inhibitors. 5

Other Medications

• Potassium-sparing diuretics (spironolactone, triamterene, amiloride) directly reduce renal potassium excretion. 1
• NSAIDs impair renal potassium excretion by reducing prostaglandin synthesis and attenuating diuretic effects. 1
• Trimethoprim and pentamidine block epithelial sodium channels in the collecting duct, leading to hyperkalemia. 1
• Heparin and derivatives suppress aldosterone synthesis, contributing to hyperkalemia. 1
• Beta-blockers impair cellular potassium uptake and can increase hyperkalemia risk even in patients with normal kidney function. 1
• Calcineurin inhibitors (cyclosporine, tacrolimus) impair renal potassium excretion. 1

Transcellular Potassium Shift

Potassium shifts from the intracellular to extracellular space cause transient hyperkalemia.

• Metabolic acidosis causes potassium to shift out of cells in exchange for hydrogen ions. 1
• Insulin deficiency impairs Na⁺/K⁺-ATPase-mediated cellular potassium uptake, causing extracellular potassium to rise. 1
• Massive tissue breakdown—including rhabdomyolysis, tumor lysis syndrome, and severe burns—releases large amounts of intracellular potassium into the bloodstream. 1
• Hemolysis can occur in the body (true hyperkalemia) or in the test tube (pseudohyperkalemia). 1

Excessive Potassium Intake

Excessive intake alone rarely causes hyperkalemia unless renal function is impaired.

• Potassium supplements are a direct exogenous source. 1
• Salt substitutes often contain potassium chloride (commonly used in DASH diet products). 1
• High-potassium foods—bananas, melons, orange juice, potatoes, tomatoes—can contribute to hyperkalemia, particularly in patients with impaired renal excretion. 1
• Excessive intake can cause hyperkalemia but usually only in the setting of impaired renal function. 2

High-Risk Comorbidities

Certain patient populations have dramatically elevated risk of developing hyperkalemia.

• Advanced CKD is strongly associated with hyperkalemia, with risk increasing proportionally as eGFR declines. 1
• Heart failure patients have markedly increased likelihood of hyperkalemia. 1
• Diabetes mellitus confers heightened risk through hyporeninemic hypoaldosteronism and insulin deficiency, even when renal function is relatively preserved. 1
• Resistant hypertension is linked to greater incidence of hyperkalemia. 1
• Recent myocardial infarction is a recognized risk factor. 1
• Advanced age raises hyperkalemia susceptibility due to age-related alterations in potassium homeostasis. 1
• Men have slightly higher risk than women after RAAS inhibitor initiation. 1

Pseudohyperkalemia

Pseudohyperkalemia represents falsely elevated potassium in the test tube without true elevation in the body.

• Caused by hemolysis during blood draw, prolonged tourniquet application, fist clenching during phlebotomy, or thrombocytosis/leukocytosis. 1
• Plasma potassium concentrations are usually 0.1-0.4 mEq/L lower than serum levels due to platelet potassium release during coagulation. 1
• If suspected, repeat measurement with proper blood sampling technique or obtain an arterial sample for confirmation. 1

Clinical Context and Prevalence

• The prevalence of hyperkalemia varies dramatically by setting: 2-4% in the general population, 10-55% in hospitalized patients, and up to 73% in advanced CKD. 1
• Both the absolute potassium level and the rate of rise determine clinical significance—rapid increases are more likely to cause cardiac abnormalities than gradual elevations over months. 1
• Multiple mechanisms often coexist (e.g., CKD + RAAS inhibitor + NSAID), amplifying hyperkalemia risk. 1
• Patients with cardiovascular disease and CKD are at risk of hyperkalemia, and 50% of these patients have two or more recurrences within 1 year. 5

References: 5 European Heart Journal 2018 - Expert consensus on hyperkalaemia management 1 Praxis Medical Insights 2026 - Hyperkalemia Causes and Risk Factors 3 Nephrology, Dialysis, Transplantation 2019 - Hyperkalemia pathophysiology 2 Cleveland Clinic Journal of Medicine 2017 - Diagnosis and treatment 4 Journal of Pediatric Pharmacology and Therapeutics 2026 - Concomitant drug-induced hyperkalemia