I. “Pseudo” hyperkalemia

1. Cellular efflux: thrombocytosis, erythrocytosis, leukocytosis, in vitro hemolysis
2. Hereditary defects in red cell membrane transport

II. Intra- to extracellular shift

1. Acidosis
2. Hyperosmolality; radiocontrast, hypertonic dextrose, mannitol
3. β-Adrenergic antagonists (noncardioselective agents)
4. Digoxin and related glycosides (yellow oleander, foxglove, bufadienolide)
5. Hyperkalemic periodic paralysis
6. Lysine, arginine, and -aminocaproic acid (structurally similar, positively charged)
7. Succinylcholine; thermal trauma, neuromuscular injury, disuse atrophy, mucositis, or prolonged immobilization
8. Rapid tumor lysis

III. Inadequate excretion

1. Inhibition of the renin-angiotensin-aldosterone axis; ↑ risk of hyperkalemia when used in combination or at higher than recommended dosages
   1. ACE inhibitors
   2. Renin inhibitors: aliskiren (in combination with ACE inhibitors or ARBs)
   3. ARBs
   4. Blockade of the mineralocorticoid receptor: spironolactone, eplerenone, drospirenone
   5. Blockade of ENaC: amiloride, triamterene, trimethoprim, pentamidine, nafamostat
2. Decreased distal delivery
   1. Congestive heart failure
   2. Volume depletion
3. Hyporeninemic hypoaldosteronism
   1. Tubulointerstitial diseases: SLE, sickle cell anemia, obstructive uropathy
   2. Diabetes, diabetic nephropathy
   3. Drugs: nonsteroidal anti-inflammatory drugs, COX-2 inhibitors, β blockers, cyclosporine, tacrolimus
   4. Chronic kidney disease, advanced age
   5. Pseudohypoaldosteronism type II: defects in WNK1 or WNK4 kinases, Kelch-like 3 (KLHL3), or Cullin 3 (CUL3)
4. Renal resistance to mineralocorticoid
   1. Tubulointerstitial diseases: SLE, amyloidosis, sickle cell anemia, obstructive uropathy, post-acute tubular necrosis
   2. Hereditary: pseudohypoaldosteronism type I: defects in the mineralocorticoid receptor or ENaC
5. Advanced renal insufficiency with low GFR
   1. Chronic kidney disease
   2. End-stage renal disease
   3. Acute oliguric kidney injury
6. Primary adrenal insufficiency
   1. Autoimmune: Addison's disease, polyglandular endocrinopathy
   2. Infectious: HIV, cytomegalovirus, tuberculosis, disseminated fungal infection
   3. Infiltrative: amyloidosis, malignancy, metastatic cancer
   4. Drug-associated: heparin, low-molecular-weight heparin
   5. Hereditary: adrenal hypoplasia congenita, congenital lipoid adrenal hyperplasia, aldosterone synthase deficiency
   6. Adrenal hemorrhage or infarction, including in antiphospholipid syndrome