What are the causes of hyperkalemia?

Causes of Hyperkalemia

Hyperkalemia develops through three primary mechanisms: increased potassium intake, reduced potassium excretion (most common), and transcellular shift of potassium from intracellular to extracellular space. 1

Primary Pathophysiologic Mechanisms

The fundamental causes of hyperkalemia can be systematically categorized:

1. Decreased Potassium Excretion (Most Common)

Impaired renal potassium excretion is the predominant cause of sustained hyperkalemia, occurring when glomerular filtration rate decreases, tubular flow is reduced, distal sodium delivery is impaired, or aldosterone-sensitive ion transporters in the distal nephron are suppressed. 2, 3

Medications That Decrease Excretion:

• RAAS inhibitors (ACE inhibitors, ARBs, mineralocorticoid receptor antagonists, direct renin inhibitors like aliskiren) 1
• Potassium-sparing diuretics (spironolactone, triamterene, amiloride) 1
• NSAIDs 1
• Sacubitril/valsartan 1
• Beta-blockers 1
• Calcineurin inhibitors (cyclosporine, tacrolimus) 1
• Trimethoprim-sulfamethoxazole 1
• Heparin 1
• Pentamidine 1
• Digitalis 1
• Penicillin G 1
• Mannitol 1

Disease States Causing Decreased Excretion:

• Chronic kidney disease (hyperkalemia occurs in up to 73% of patients with advanced CKD) 1
• Acute kidney injury 4
• Diabetes mellitus (associated with hypoaldosteronism) 1, 5
• Adrenal disease/hypoaldosteronism 5, 2
• Heart failure (hyperkalemia occurs in up to 40% of patients with chronic HF) 1

2. Increased Potassium Intake/Administration

Excessive potassium intake typically causes hyperkalemia only when combined with impaired renal function, as normal kidneys can excrete large potassium loads. 3

Dietary and Supplemental Sources:

• Potassium supplements 1
• Salt substitutes (DASH diet products) 1
• High-potassium foods (bananas, melons, orange juice, potatoes, tomato products, legumes, yogurt, chocolate) 1
• Herbal supplements (alfalfa, dandelion, hawthorne berry, horsetail, lily of the valley, milkweed, nettle, noni juice, Siberian ginseng, dried toad skin) 1
• Amino acids (aminocaproic acid, arginine, lysine) 1
• Stored blood products 1

3. Transcellular Potassium Shift

Potassium shift from intracellular to extracellular space causes transient hyperkalemia, particularly when combined with reduced renal excretion. 2, 3

Causes of Transcellular Shift:

• Metabolic acidosis 1
• Tissue destruction (catabolism, infection, surgery, chemotherapy, tumor lysis syndrome) 1
• Hemolysis (in vivo, not in vitro) 1
• Insulin deficiency 2
• Hyperglycemia 2
• Beta-blocker therapy (impairs cellular uptake) 1

4. Pseudo-hyperkalemia

Pseudo-hyperkalemia refers to falsely elevated potassium levels in the test tube without true hyperkalemia in the body, caused by potassium release from blood cells during or after sampling. 1, 5

Causes of Pseudo-hyperkalemia:

• Hemolysis during blood draw (repeated fist clenching, poor phlebotomy technique) 1
• Prolonged tourniquet time 1
• Thrombocytosis or leukocytosis (platelet or white blood cell release during clotting) 1

When pseudo-hyperkalemia is suspected, repeat measurement with properly obtained blood sample or arterial sample. Plasma potassium concentrations are typically 0.1-0.4 mEq/L lower than serum levels due to platelet potassium release during coagulation. 1

High-Risk Clinical Scenarios

The risk of hyperkalemia increases substantially when multiple risk factors coexist, particularly in patients with cardiovascular disease combined with renal impairment, diabetes, and advanced age. 1

Specific High-Risk Populations:

• Patients on RAAS inhibitors with CKD (incidence increases from <2% with monotherapy to 5-10% with dual RAAS inhibition in CKD/HF patients) 1
• Heart failure patients with comorbid renal insufficiency and/or diabetes 6
• Advanced CKD patients (prevalence 2-4% in general population vs. 10-55% in hospitalized patients) 1
• Patients on multiple potassium-retaining medications 1, 7

Non-Renal Causes Requiring Investigation

When hyperkalemia persists despite dietary potassium restriction, investigate non-dietary causes systematically: 1

• Spurious laboratory values (pseudo-hyperkalemia) 1
• Hemolysis (in vivo vs. in vitro) 1
• Metabolic acidosis 1
• Exogenous potassium sources (medications, supplements, salt substitutes) 1
• Constipation (reduced gastrointestinal potassium elimination) 1
• Inadequate dialysis (in dialysis-dependent patients) 1
• Medication review (ACE inhibitors, ARBs, NSAIDs, potassium-sparing diuretics) 1

Critical Clinical Pitfall

The most important clinical pitfall is discontinuing life-saving RAAS inhibitor therapy due to hyperkalemia. Hyperkalemia leads to frequent hospitalizations and increased mortality, especially when stringent monitoring is not performed, but discontinuation of RAAS inhibitors in patients with heart failure or CKD is associated with higher risk of mortality and major adverse cardiovascular events than continuation with appropriate hyperkalemia management. 1