Hyperkalemia
A) Transcellular shift:

Insulin deficiency

Hyperosmolality (eg, hyperglycemia, mannitol)

Nonselective beta-blockers

Digitalis

Metabolic acidosis

Depolarizing muscle relaxant (succinylcholine)

Familial periodic paralysis

Tumor lysis syndrome

B) Cellular disruption with release of potassium:

Crush injuries

Reperfusion of ischemic limbs

Massive blood transfusion

Lysed erythrocyte in large hematomas

Rhabdomyolysis

C) Decreased renal K+ excretion: Renal failure

D) Drugs: ACE inhibitors, angiotensin receptor blockers, NSAIDs, potassium sparing diuretics (spironolactone), cyclosporine

E) Spurious:

Thrombocytosis (> 1,000,000/mm3)

Lekocytosis (> 50,000/mm3)

Hemolysis

Hypokalemia

Acute alkalosis

Administration of glucose and insulin

Catecholamines

Increased gastrointestinal loss

Diarrhea, vomiting, high NG output

Mucus secreting colon tumors (eg, villous adenoma)

Excessive renal loss

Metabolic alkalosis

Magnesium deficiency

Hyperaldosteronism
Hypercalcemia
Mnemonic VITAMIN TRAPS:

Vitamin A and D intoxication

Immobilization

Thyrotoxicosis

Addison's disease/acidosis

Milk-alkali syndrome (from calcium antacids)

Inflammatory disorders

Neoplastic disease:

Multiple myleoma, lymphoma, metastatic breast cancer (associated with bone destruction)

Squamous cell carcinoma of the head and neck, esophagus, lung, kidney, and GI tract cancer (tumors that elaborate humoral factors causing ↑ Ca++)

Thiazides and other drugs (eg, lithium)

Rhabdomyolysis

AIDS

Paget's disease/ Parenteral nutrition/ Parathyroid disease (hyperparathyroidism)

Sarcoidosis

Hypocalcemia

Hypoparathyroidism

Acute pancreatitis

Massive soft tissue infection such as necrotizing fasciitis

Pancreatic/small bowel fistula

Vitamin D deficiency

Renal failure

Severe magnesium deficiency

Crush injuries

Massive blood transfusion

Hypermagnesemia

Acute/chronic renal failure

Magnesium-containing antacids

Severe burns

Crush injuries

Rhabdomyolysis

Severe metabolic acidosis

Hypomagnesemia

Intestinal malabsorption

Excessive GI loss (severe diarrhea, vomiting, enteric fistula, use of purgatives, NG suction)

Chronic use of loop diuretics

Drugs: cyclosporine, aminoglycosides, cisplatin, insulin

Alcohol abuse

Hyperaldosteronism

Hypercalcemia

Severe burns

Acute pancreatitis

Diabetic ketoacidosis

Hypernatremia

Hypervolemic hypernatremia: hypertonic Na load, Cushing syndrome, hyperaldosteronism

Hypo/euovolemic hypernatremia: diabetes insipidus, insensible water loss, diuretics

Hyponatremia

Hypervolemic hyponatremia:CHF,cirrhosis,severe nephritic syndrome, renal failure

Hypovolemic hyponatremia:vomiting, diuretics, diarrhea, dehydration

Euvolemic hyponatremia:Addison disease, hypothyroidism, SIADH

Other: primary polydepsia, post-transurethral resection of the prostate (TURP) syndrome, hyperglycemia