Fluid and Electrolytes Lecture Notes

Jun 30, 2024

Review flashcards

Fluid and Electrolytes Lecture Notes

Importance and Function

  • Proper balance is essential: not too much, not too little
  • 70% of body is water, found in brain, muscles, bones, blood (83% water)
  • Water's role: nutrient transport, oxygen transport, part of blood composition
  • Electrolytes in water are crucial: they produce electrical charges (ions)

Key Electrolytes

  • Main Electrolytes: Potassium, Sodium, Chloride, Calcium, Phosphate, Magnesium
  • Roles:
    • Muscle contraction
    • Nerve impulses
    • Bone creation
    • Fluid balance (osmosis)
    • Blood acid-base balance

Electrolyte Maintenance

  • Gained mostly through food
  • Absorbed in the gut, filtered by kidneys
  • Nephrons in kidneys balance electrolyte levels
  • Issues with the gut/kidneys can cause imbalances
  • Diuretics can affect electrolyte levels
  • Losses through trauma, blood loss, burns, vomiting, diarrhea

Sodium (Na⁺)

Normal Levels: 135-145 mEq/L

  • Hypernatremia: >145 mEq/L
    • Causes: Excessive sodium intake, dehydration, Cushing's syndrome, Conns syndrome, diabetes insipidus
    • Symptoms: Fatigue, restlessness, increased reflexes, extreme thirst, decreased urine output, dry mouth/skin
  • Hyponatremia: <135 mEq/L
    • Causes: Insufficient sodium intake, diuretics (thiazides), vomiting/diarrhea, Addison's disease, SIADH
    • Symptoms: Seizures, abdominal cramping, lethargy, decreased tendon reflexes, orthostatic hypotension, muscle spasms

Chloride (Cl⁻)

Normal Levels: 95-105 mEq/L

  • Hypochloremia: <95 mEq/L
    • Causes: GI issues, diuretics (thiazides), burns, cystic fibrosis, SIADH
    • Symptoms: Dehydration, increased heart rate, decreased blood pressure, fever, vomiting, lethargy
  • Hyperchloremia: >105 mEq/L
    • Causes: Excessive sodium intake, dehydration, decreased bicarb levels, conns syndrome, corticosteroids
    • Symptoms: Similar to hypernatremia and acidosis

Potassium (K⁺)

Normal Levels: 3.5-5 mEq/L

  • Hypokalemia: <3.5 mEq/L
    • Causes: Loop diuretics, corticosteroids, excessive insulin, Cushing's syndrome, vomiting/NG suction
    • Symptoms: Lethargy, shallow respirations, cardiac dysrhythmias (ST depression, shallow T wave, projecting U wave), frequent urination, leg cramps, limp muscles, low blood pressure
  • Hyperkalemia: >5 mEq/L
    • Causes: Burns, tissue damage (rhabdomyolysis), Addison's disease, renal failure, potassium-sparing diuretics
    • Symptoms: Muscle weakness, little/no urine output, respiratory failure, decreased cardiac contractility, muscle twitches, rhythm changes (tall peaked T waves)

Calcium (Ca²⁺)

Normal Levels: 8.5-10.5 mg/dL

  • Hypocalcemia: <8.5 mg/dL
    • Causes: Decreased PTH, insufficient calcium intake, low Vitamin D, CKD, bisphosphonates, aminoglycosides, anticonvulsants
    • Symptoms: Convulsions, hyperactive reflexes, arrhythmias (prolonged QT), muscle spasms, positive Trousseau's and Chvostek's signs, tingling/numbness
  • Hypercalcemia: >10.5 mg/dL
    • Causes: Overactive parathyroid, increased Vitamin D, cancer spread to bones, thiazide diuretics, lithium
    • Symptoms: Weakness, EKG changes (shortened QT), absent reflexes, abdominal distension, kidney stones

Magnesium (Mg²⁺)

Normal Levels: 1.5-2.5 mg/dL

  • Hypomagnesemia: <1.5 mg/dL
    • Causes: Poor intake, electrolyte imbalances, malabsorption disorders, PPIs, alcoholism
    • Symptoms: Positive Trousseau's and Chvostek's signs, weakness, increased reflexes, torsades de pointes, tetany, low calcium/potassium, hypertension
  • Hypermagnesemia: >2.5 mg/dL
    • Causes: Excess supplementation, renal failure, OB patients on magnesium sulfate
    • Symptoms: Lethargy, EKG changes (prolonged PR/QT), absent reflexes, hypotension, bradycardia, red/hot face, nausea/vomiting, impaired breathing, confusion

Phosphate (PO₄³⁻)

Normal Levels: 2.5-4.5 mg/dL

  • Hypophosphatemia: <2.5 mg/dL
    • Causes: Overuse of aluminum antacids, starvation, refeeding syndrome, overactive parathyroid, low Vitamin D
    • Symptoms: Bone pain, fractures, osteomalacia, neuro status changes, erythrocyte destruction
  • Hyperphosphatemia: >4.5 mg/dL
    • Causes: Overuse of phosphate laxatives, renal failure, rhabdomyolysis, hypoparathyroidism
    • Symptoms: Similar to hypocalcemia, convulsions, hyperactive reflexes, arrhythmias, muscle spasms, itching, positive Trousseau's and Chvostek's signs

Conclusion

  • Access the free quiz for self-testing on this material
  • Review individual electrolyte videos for nursing interventions and treatments