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Chapter 41: Electrolytes Imbalance

Major Cations

  • Extracellular: Sodium (Na+)

  • Intracellular: Potassium (K+)

Electrolyte Imbalances

  • Sodium Imbalances: Hyponatremia, Hypernatremia

  • Potassium Imbalances: Hypokalemia, Hyperkalemia

  • Magnesium Imbalances: Hypomagnesemia, Hypermagnesemia

  • Calcium Imbalances: Hypocalcemia, Hypercalcemia

  • Phosphate Imbalances: Hypophosphatemia, Hyperphosphatemia

  • Chloride Imbalances: Hypochloremia, Hyperchloremia

Sodium (Na+)

  • Role: Major extracellular cation, attracts fluid, helps to preserve fluid volume, and regulates acid-base balance.

  • Normal Range of Serum Sodium: 135 - 145 mEq/L

  • Fluid and Sodium Relationship:

    • Increase in Na+ intake leads to increased extracellular fluid concentration.

    • Increased serum Na+ triggers thirst and release of ADH, promoting kidney water retention.

    • Aldosterone is involved in sodium and water conservation when serum Na+ levels are low.

Sodium-Potassium Pump

  • Maintains normal intracellular and extracellular concentrations of sodium and potassium.

  • Uses ATP and magnesium.

  • Prevents cell swelling and creates electrical charge for neuromuscular impulse transmission.

Hyponatremia

  • Definition: Serum Na+ level < 135 mEq/L.

  • Symptoms: Delayed/slowed depolarization of membranes, primarily neurologic symptoms including headache, nausea/vomiting, muscle twitching, altered mental status, stupor, seizures, and coma.

  • Types of Hyponatremia:

    • Dilutional: Na+ loss with water gain.

    • Depletional: Insufficient Na+ intake.

    • Hypovolemic: Na+ loss > water loss (can be renal or non-renal loss).

    • Hypervolemic: Water gain > Na+ gain, often with edema.

    • Isovolumic: Normal Na+ level with excess fluid.

Clinical Presentation of Hyponatremia

  • Hypovolemic Presence: Poor skin turgor, tachycardia, decreased BP, orthostatic hypotension.

  • Hypervolemic Presence: Edema, hypertension, weight gain, bounding tachycardia.

Treatment for Hyponatremia

  • Mild Cases:

    • Restrict fluid intake for hyper/isovolemic types.

    • Administer IV fluids or increase oral Na+ intake for hypovolemic.

  • Severe Cases: Infuse hypertonic NaCl solution (3% or 5% NaCl), administer furosemide to remove excess fluid, and monitor in an ICU setting.

Hypernatremia

  • Definition: Sodium level > 145 mEq/L.

  • Symptoms: Characterized as "S-A-L-T" (Skin flushed, Agitation, Low-grade fever, Thirst) alongside neurological symptoms, seizures, and muscle twitching.

  • Causes: Water deficit, excessive Na+ ingestion, diabetes insipidus.

Clinical Presentation of Hypernatremia

  • Signs of hypervolemia such as skin flushed and agitation, low-grade fever, thirst, seizures.

Treatment for Hypernatremia

  • Correct the underlying disorder through gradual fluid replacement.

  • Monitor for signs/symptoms of cerebral edema and monitor serum Na+ levels.

  • Ensure seizure precautions are in place.

Potassium (K+)

  • Role: Major intracellular cation, essential for transmission of electrical impulses in skeletal and cardiac muscle.

  • Normal Range of Serum K+: 3.5 - 5 mEq/L

Balancing Potassium

  1. Renal excretion is the primary means of regulating K+.

  2. Na+/K+ pump function.

  3. pH levels impact potassium regulation via hydrogen ions.

Hypokalemia

  • Definition: Serum K+ < 3.5 mEq/L.

  • Causes: GI losses, insufficient intake, renal loss from diuretics, diaphoresis.

Clinical Presentation of Hypokalemia

  • Use the acronym "S-U-C-T-I-O-N":

    • Skeletal muscle weakness.

    • U wave changes in EKG.

    • Constipation, ileus.

    • Toxicity of digitalis glycosides.

    • Irregular and weak pulse.

    • Orthostatic hypotension.

    • Numbness (paresthesia).

Treatment for Hypokalemia

  • Increase dietary K+.

  • Administer oral potassium supplements or IV K+ replacement, considering EKG monitoring.

IV K+ Replacement Guidelines

  • Concentrations must not exceed 40-60 mEq/L.

  • Recommended rates are usually 10-20 mEq/hr; never give IV push potassium.

Hyperkalemia

  • Definition: Serum K+ > 5 mEq/L.

  • Causes: Altered kidney function, increased intake, acidosis, uncontrolled diabetes.

Clinical Presentation of Hyperkalemia

  • Symptoms include irritability, paresthesia, muscle weakness (especially in the legs), EKG changes such as tented T wave, irregular pulse, hypotension, nausea, abdominal cramps, diarrhea.

Treatment for Hyperkalemia

  • Mild cases: Use loop diuretics, dietary restrictions.

  • Moderate cases: Administer Kayexalate.

  • Emergency treatment: 10% calcium gluconate for cardiac effects, glucose with insulin, sodium bicarbonate for acidosis.

Magnesium (Mg++)

  • Essential for ATP production, protein synthesis, carbohydrate metabolism, cardiovascular function, regulation of muscle contractions.

  • Normal Range: 1.3 - 2.1 mEq/L

Hypomagnesemia

  • Definition: Serum Mg++ < 1.3 mEq/L.

  • Causes: Poor dietary intake, GI absorption issues, excessive losses.

  • High-risk patients: Those with chronic alcoholism, malabsorption, GI disorders, sepsis, and significant burns.

Symptoms of Hypomagnesemia

  • CNS: Altered level of consciousness, confusion, hallucinations.

  • Neuromuscular: Muscle weakness, leg/foot cramps, hyperactive deep tendon reflexes (DTRs), tetany, Chvostek’s and Trousseau’s signs.

  • Cardiovascular: Tachycardia, hypertension, EKG changes.

  • Gastrointestinal: Dysphagia, anorexia, nausea/vomiting, hypoactive bowel sounds.

Treatment for Hypomagnesemia

  • Administer magnesium sulfate infusion via pump, not exceeding 150 mg/min, and monitor vital signs and serum magnesium levels.

  • Use calcium gluconate as an antidote for magnesium overdose.

Hypermagnesemia

  • Definition: Serum Mg++ > 2.1 mEq/L.

  • Causes: Renal dysfunction, renal failure, Addison’s disease, adrenocortical insufficiency, untreated diabetic ketoacidosis (DKA).

Symptoms of Hypermagnesemia

  • Decreased neuromuscular activity, hypoactive DTRs, generalized weakness, possible nausea/vomiting.

Treatment for Hypermagnesemia

  • Increase fluids if renal function is normal.

  • Administer loop diuretics if no response to fluids.

  • Provide calcium gluconate for toxicity and mechanical ventilation for respiratory depression. Hemodialysis with Mg++-free dialysate may be necessary.

Calcium (Ca++)

  • Critical for bone structure, cell membrane permeability, muscle contraction, blood clotting.

  • Normal Range: 8.5 - 10.5 mg/dL

Calcium Regulation

  • Influenced by vitamin D intake, dietary intake, and body stores.

  • Parathyroid hormone increases serum Ca++ by releasing from bones; calcitonin lowers serum levels, inhibiting calcium loss from bones.

Hypocalcemia

  • Definition: Serum calcium < 8.5 mg/dL.

  • Causes: Poor intake, malabsorption, pancreatitis, thyroid/parathyroid surgery, loop diuretics, low magnesium levels.

Symptoms of Hypocalcemia

  • Neuromuscular symptoms include anxiety, confusion, irritability, muscle twitching, paresthesia (in the mouth, fingers, toes), tetany.

  • Signs include Chvostek’s and Trousseau’s, fractures, diarrhea, diminished response to digoxin, and EKG changes.

Treatment for Hypocalcemia

  • Administration of calcium gluconate for patients who have had thyroid or parathyroid surgery.

  • Monitor cardiac activity closely.

  • Oral or IV calcium replacement as required.

Hypercalcemia

  • Definition: Serum calcium > 10.5 mg/dL.

  • Major Causes: Cancer, hyperparathyroidism, chronic immobility.

Symptoms of Hypercalcemia

  • Fatigue, confusion, lethargy, muscle weakness, bradycardia, cardiac arrest, dysrhythmias, anorexia, nausea/vomiting, decreased bowel sounds, constipation, polyuria, renal calculi, and renal failure.

Treatment for Hypercalcemia

  • If asymptomatic, treat the underlying cause.

  • Hydrate the patient to encourage diuresis, use loop diuretics, and administer corticosteroids.

Phosphorus

  • The primary anion in intracellular fluid, essential for cell membrane integrity, muscle and neurologic function, and metabolism of carbohydrates, fats, and proteins.

  • Normal Range: 2.5 – 4.5 mg/dL; inversely proportional to calcium levels.

Hypophosphatemia

  • Definition: Serum phosphorus < 2.5 mg/dL.

  • Consequences: Can lead to organ system failure.

  • Causes: Respiratory alkalosis, insulin release, malabsorption, diuretics, DKA, elevated parathyroid hormone levels, extensive burns.

Symptoms of Hypophosphatemia

  • Musculoskeletal: Muscle weakness, respiratory muscle failure, osteomalacia, pathological fractures.

  • CNS: Confusion, anxiety, seizures, coma.

  • Cardiac: Hypotension and decreased cardiac output.

  • Hematologic: Hemolytic anemia, easy bruising, infection risk.

Treatment for Hypophosphatemia

  • For mild to moderate hypophosphatemia: Dietary interventions and oral supplements.

  • For severe cases: IV replacement with potassium phosphate or sodium phosphate.

Hyperphosphatemia

  • Definition: Serum phosphorus > 4.5 mg/dL.

  • Causes: Impaired kidney function, cell damage, hypoparathyroidism, respiratory acidosis, DKA, increased dietary intake.

Symptoms of Hyperphosphatemia

  • Memory Aid: C-H-E-M-O

    • Cardiac irregularities.

    • Hyperreflexia.

    • Eating poorly.

    • Muscle weakness.

    • Oliguria.

Treatment for Hyperphosphatemia

  • Implement a low-phosphorus diet.

  • Administer antacids that bind phosphorus to decrease absorption.

  • Treat underlying causes of respiratory acidosis or DKA.

  • For severe hyperphosphatemia in patients with good kidney function, administer IV saline.

Chloride (Cl-)

  • Role: Major extracellular anion, helps maintain blood volume, pressure, and pH balance.

  • Normal Range: 96 - 106 mEq/L.

  • Secreted in the stomach as hydrochloric acid and aids in carbon dioxide transport in the blood.

Hypochloremia

  • Definition: Serum chloride < 96 mEq/L.

  • Causes: Decreased intake, metabolic alkalosis, diuretic use, laxative abuse, vomiting, diarrhea, and fever.

Symptoms of Hypochloremia

  • Agitation, irritability, hyperactivity of DTRs, muscle cramps, hypertonicity, shallow, slow respirations, seizures, coma, arrhythmias.

Treatment for Hypochloremia

  • Mild cases: Increase NaCl intake or potassium salts (KCl), and foods high in sodium.

  • Severe cases: Administer IV fluids of normal saline.

Hyperchloremia

  • Definition: Serum chloride > 106 mEq/L; usually occurs with other imbalances.

  • Causes: Dehydration, renal failure, respiratory alkalosis, salicylate toxicity, hyperparathyroidism, hyperaldosteronism, hypernatremia.

Symptoms of Hyperchloremia

  • Often related to metabolic acidosis, symptoms include decreased LOC/confusion, Kussmaul’s respirations, weakness, hypernatremia, agitation, tachycardia, dyspnea, tachypnea, hypertension, edema, and swollen tongue.

Treatment for Hyperchloremia

  • Correct the underlying cause, restore fluid, electrolyte, and acid-base balance.

  • Consider using IV Lactated Ringer’s solution to correct acidosis.