What are the causes and treatments of potassium (K+), sodium (Na+), calcium (Ca2+), magnesium (Mg2+), chloride (Cl-), and phosphate (PO4) disorders?

Causes and Treatment of Electrolyte Disorders

The management of electrolyte disorders should address the underlying cause of the imbalance while promptly treating the electrolyte abnormality to prevent life-threatening complications such as cardiac arrhythmias, seizures, and death. 1

Potassium (K+) Disorders

Hypokalemia (K+ < 3.5 mEq/L)

Causes:

• Inadequate intake
• Gastrointestinal losses (vomiting, diarrhea)
• Renal losses (diuretics, hyperaldosteronism)
• Intracellular shifts (alkalosis, insulin)
• Dialysis with low-potassium solutions 2

Treatment:

• Mild (3.0-3.5 mEq/L): Oral potassium chloride 40-80 mEq/day in divided doses 1
• Moderate (2.5-3.0 mEq/L): Oral potassium chloride 80-120 mEq/day in divided doses 1
• Severe (<2.5 mEq/L): IV potassium at 10-20 mEq/hour (not exceeding 40 mEq/hour in critical situations) with continuous cardiac monitoring 1
• Address underlying cause (stop diuretics, correct alkalosis) 2

Hyperkalemia (K+ > 5.0 mEq/L)

Causes:

• Decreased renal excretion (renal failure, medications like ACE inhibitors, ARBs, NSAIDs)
• Excessive intake (supplements, salt substitutes)
• Cellular release (rhabdomyolysis, tumor lysis syndrome, acidosis)
• Pseudohyperkalemia (hemolysis during blood draw)

Treatment:

1. Eliminate potassium-containing foods and medications 3
2. Calcium gluconate IV (if ECG changes present)
3. Insulin with glucose (10-20 units in 500 mL of 10% dextrose) 3
4. Sodium bicarbonate for acidosis
5. Exchange resins, hemodialysis, or peritoneal dialysis for severe cases 3

Sodium (Na+) Disorders

Hyponatremia (Na+ < 135 mEq/L)

Causes:

• Pseudohyponatremia (hyperproteinemia, hyperlipidemia, hyperglycemia)
• Hypovolemic (GI losses, renal losses, third-spacing)
• Hypervolemic (heart failure, cirrhosis, renal failure)
• Euvolemic (SIADH, hypothyroidism, adrenal insufficiency) 4

Treatment:

• Hypovolemic: Isotonic saline rehydration 4
• Hypervolemic: Treat underlying cause, fluid restriction, diuretics 4
• Euvolemic: Free water restriction, address underlying cause, consider vasopressin receptor antagonists 4
• Severe/symptomatic: Hypertonic saline (3%) with careful monitoring to avoid overly rapid correction (limit to 8-10 mEq/L in 24 hours) 4, 5

Hypernatremia (Na+ > 145 mEq/L)

Causes:

• Water loss (diabetes insipidus, excessive sweating, fever)
• Inadequate water intake (altered mental status, inability to access water)
• Excessive sodium intake (iatrogenic, salt ingestion) 4

Treatment:

• Calculate free water deficit
• Correct with hypotonic fluids (oral or IV)
• Slow correction (no more than 10 mEq/L/day) to prevent cerebral edema 4, 5
• Address underlying cause 1

Calcium (Ca2+) Disorders

Hypocalcemia (Ca2+ < 8.5 mg/dL)

Causes:

• Hypoparathyroidism
• Vitamin D deficiency
• Renal failure
• Pancreatitis
• Medication-induced (bisphosphonates, anticonvulsants)
• Hypomagnesemia 6

Treatment:

• Symptomatic/severe: IV calcium gluconate 1-2 g
• Chronic: Oral calcium supplements with vitamin D
• Correct hypomagnesemia if present
• Address underlying cause 6, 7

Hypercalcemia (Ca2+ > 10.5 mg/dL)

Causes:

• Hyperparathyroidism
• Malignancy
• Vitamin D toxicity
• Granulomatous diseases
• Thiazide diuretics 8

Treatment:

• Hydration with isotonic saline
• Loop diuretics after volume repletion
• Bisphosphonates for severe cases
• Calcitonin for acute management
• Treat underlying cause 7

Magnesium (Mg2+) Disorders

Hypomagnesemia (Mg2+ < 1.7 mg/dL)

Causes:

• Decreased intake
• GI losses (diarrhea, malabsorption)
• Renal losses (diuretics, alcohol, medications)
• Continuous renal replacement therapy 2
• Proton pump inhibitor use 1

Treatment:

• Mild (1.2-1.7 mg/dL): Oral magnesium oxide/citrate 400-800 mg/day in divided doses 1
• Moderate (0.8-1.2 mg/dL): Oral magnesium 800-1600 mg/day in divided doses 1
• Severe (<0.8 mg/dL): IV magnesium sulfate 1-2 g over 1 hour, followed by 0.5-1 g every 6 hours 1
• For patients on CKRT: Use magnesium-containing dialysis solutions 2

Hypermagnesemia (Mg2+ > 2.5 mg/dL)

Causes:

• Renal failure
• Excessive intake (antacids, laxatives)
• Iatrogenic (IV magnesium administration)

Treatment:

• Discontinue magnesium-containing products
• Hydration with isotonic saline
• Loop diuretics
• Calcium gluconate for severe symptoms
• Hemodialysis for severe cases 7

Chloride (Cl-) Disorders

Hypochloremia (Cl- < 95 mEq/L)

Causes:

• Vomiting, nasogastric suction
• Diuretic use
• Metabolic alkalosis
• Congestive heart failure

Treatment:

• Address underlying cause
• Normal saline infusion
• Potassium chloride if hypokalemia present 7

Hyperchloremia (Cl- > 108 mEq/L)

Causes:

• Excessive normal saline administration
• Renal tubular acidosis
• Diarrhea
• Acetazolamide use

Treatment:

• Address underlying cause
• Switch to balanced crystalloid solutions
• Treat metabolic acidosis if present 7

Phosphate (PO4) Disorders

Hypophosphatemia (PO4 < 2.5 mg/dL)

Causes:

• Refeeding syndrome
• Alcoholism
• Diabetic ketoacidosis treatment
• Respiratory alkalosis
• Continuous renal replacement therapy 2

Treatment:

• Mild (2.0-2.5 mg/dL): Oral phosphate 1000-2000 mg/day in divided doses 1
• Moderate (1.0-2.0 mg/dL): Oral phosphate 2000-3000 mg/day in divided doses 1
• Severe (<1.0 mg/dL): IV phosphate 0.08-0.16 mmol/kg over 4-6 hours 1
• For patients on CKRT: Use phosphate-containing dialysis solutions 2

Hyperphosphatemia (PO4 > 4.5 mg/dL)

Causes:

• Renal failure
• Tumor lysis syndrome
• Rhabdomyolysis
• Excessive intake

Treatment:

• Phosphate binders (calcium acetate, sevelamer)
• Dietary phosphate restriction
• Dialysis for severe cases
• Treat underlying cause 7

Special Considerations

1. Electrolyte disorders in kidney replacement therapy (KRT):

   • Use dialysis solutions containing potassium, phosphate, and magnesium to prevent electrolyte disorders 2
   • Commercial KRT solutions enriched with these electrolytes are widely available and should be used to prevent depletion 2

2. Monitoring and prevention:

   • Monitor electrolytes frequently in high-risk patients (critically ill, on diuretics, dialysis)
   • Replace ongoing losses on a volume-for-volume basis 1
   • Consider prophylactic supplementation in high-risk scenarios

3. Cardiac implications:

   • Electrolyte disorders can lead to life-threatening arrhythmias 8
   • ECG monitoring is essential during correction of severe electrolyte abnormalities 2
   • Potassium disorders particularly affect cardiac conduction and can cause fatal arrhythmias 8

4. Neurologic manifestations:

   • Electrolyte disorders can present with neurologic symptoms ranging from mild confusion to seizures and coma 6, 5
   • Rate of correction is critical to prevent neurologic complications (central pontine myelinolysis in hyponatremia) 6