Electrolytes

Unit 10: Electrolytes

Sodium (Na+)

  • Normal Range: 135–145 mEq/L

  • Function:

    • Responsible for resting membrane potential.

    • Essential in depolarization.

    • Principal cation of the extracellular fluid (ECF).

    • Sodium-Potassium (Na-K) pump is an important mechanism.

  • Homeostasis:

    • Moves out of the cell by the Na-K pump.

    • Regulated by aldosterone and Atrial Natriuretic Peptide (ANP).

  • Dietary Sources:

    • Breads, cereals, chips, cheese, processed meats (e.g., lunch meats, hot dogs, bacon, ham).

    • Commercially canned foods.

    • Table salt.

Electrolyte Imbalances: Sodium

Hyponatremia <135 mEq/L

  • Causes:

    • Hypovolemic hyponatremia.

    • Diuretics.

    • GI fluid loss (vomiting, diarrhea).

    • Profuse sweating (diaphoresis).

    • Water intoxication.

    • Prolonged use of hypotonic IV solutions.

    • Syndrome of inappropriate antidiuretic hormone secretion (SIADH).

  • Clinical Manifestations:

    • Lethargy, confusion, weakness.

    • Muscle cramping.

    • Seizures.

    • Anorexia, nausea, vomiting.

    • Serum osmolality <285 mOsm/kg.

Hypernatremia >145 mEq/L

  • Causes:

    • Excess sodium due to:

    • Excessive sodium intake.

    • Hypertonic IV solutions.

    • Hypertonic enteral feedings without adequate water.

    • Excess loss of water due to:

    • Diarrhea.

    • Inadequate intake of water.

    • Insensible loss due to fever.

  • Clinical Manifestations:

    • Thirst, dry and sticky mucous membranes, weakness, elevated temperature.

    • Severe cases: confusion, irritability, decreased levels of consciousness, hallucinations, and seizures.

    • Serum osmolality >290 mOsm/kg.

Hyponatremia Interventions:

  • Monitor Vital Signs (V/S), Intake & Output (I&O).

  • Monitor laboratory results (serum sodium and serum osmolality).

    • Ensure Na+ levels increase by only 4 to 6 mEq/L in any 24-hour period.

  • Encourage foods high in sodium.

  • Restrict water intake.

  • Administer hypertonic IV saline solutions.

Hypernatremia Interventions:

  • Monitor V/S, I&O, laboratory results (serum sodium and serum osmolality).

  • Monitor the level of consciousness.

  • Limit salt intake and foods high in sodium.

  • Increase water intake.

  • Administer hypotonic IV solutions.

Potassium (K+)

  • Normal Range: 3.5–5 mEq/L

  • Function:

    • Works with Na+ to produce resting membrane potential.

    • Essential in depolarization.

    • Principal cation of the intracellular fluid (ICF).

    • Essential component of Na-K pump.

    • Involved in protein synthesis.

  • Homeostasis:

    • Moves into the cell via Na-K pump.

    • Regulated by the kidneys.

  • Dietary Sources:

    • Fish (excluding shellfish), whole grains, nuts, broccoli, cabbage, carrots, celery, cucumbers, potatoes with skins, spinach, tomatoes, apricots, bananas, cantaloupe, nectarines, oranges, tangerines.

Electrolyte Imbalances: Potassium

Hypokalemia <3.5 mEq/L

  • Causes:

    • Loss of potassium due to:

    • Vomiting, gastric suction, diarrhea.

    • Laxative abuse, frequent enemas.

    • Use of potassium-wasting diuretics.

    • Inadequate intake.

    • Hyperaldosteronism.

  • Clinical Manifestations:

    • Weak, irregular pulse.

    • Fatigue, lethargy.

    • Anorexia, nausea, vomiting.

    • Muscle weakness and cramping.

    • Decreased peristalsis, hypoactive bowel sounds.

    • Paresthesia.

    • Cardiac dysrhythmias; increased risk for digitalis toxicity.

Hyperkalemia >5 mEq/L

  • Causes:

    • Renal failure.

    • Massive trauma, crushing injuries, burns.

    • Hemolysis.

    • IV potassium administration.

    • Potassium-sparing diuretics.

    • Acidosis, especially diabetic ketoacidosis.

  • Clinical Manifestations:

    • Anxiety, irritability, confusion.

    • Dysrhythmias (including bradycardia and heart block).

    • Muscle weakness, flaccid paralysis.

    • Paresthesia.

    • Abdominal cramping.

Hypokalemia Interventions:

  • Monitor V/S, especially heart rate (HR).

  • Monitor ECG.

  • Monitor laboratory results (serum potassium).

  • Assess for signs of digitalis toxicity.

  • Encourage foods high in potassium.

  • Administer potassium supplements.

  • IV potassium:

    • Must be diluted and administered slowly, usually by infusion.

    • NEVER administer potassium as an IV bolus or IV push.

Hyperkalemia Interventions:

  • Monitor V/S, especially HR.

  • Monitor ECG.

  • Monitor laboratory results (serum potassium).

  • Limit potassium-rich foods.

  • Administer cation-exchange resins (e.g., Kayexalate).

  • Administer glucose and insulin as needed.

Calcium (Ca2+)

  • Normal Range: 9–10.5 mg/dL

  • Function:

    • Primary component of bones and teeth.

    • Role in:

    • Blood clotting.

    • Nerve impulse transmission.

    • Cardiac conduction.

    • Muscle contraction.

  • Homeostasis:

    • Deficit regulated by parathyroid hormone (PTH) and calcitriol.

    • Excess regulated by calcitonin.

  • Dietary Sources:

    • Cheese, ice cream, milk, yogurt, rhubarb, spinach, tofu.

Electrolyte Imbalances: Calcium

Hypocalcemia <9 mg/dL

  • Causes:

    • Hypoparathyroidism.

    • Pancreatitis.

    • Vitamin D deficiency.

    • Inadequate intake of calcium-rich foods.

    • Hyperphosphatemia.

    • Chronic alcoholism.

  • Clinical Manifestations:

    • Confusion, anxiety.

    • Numbness and tingling of extremities.

    • Muscle cramps that progress to tetany and seizures.

    • Hyperactive reflexes.

    • Cardiac dysrhythmias.

    • Positive Chvostek and Trousseau signs.

Hypercalcemia >10.5 mg/dL

  • Causes:

    • Prolonged bed rest.

    • Hyperparathyroidism.

    • Bone malignancy.

    • Paget disease.

    • Osteoporosis.

  • Clinical Manifestations:

    • Lethargy, stupor, coma.

    • Decreased muscle strength and tone.

    • Anorexia, nausea, vomiting.

    • Constipation.

    • Pathologic fractures.

    • Dysrhythmias.

    • Renal calculi.

Hypocalcemia Interventions:

  • Monitor V/S, especially HR.

  • Monitor ECG.

  • Institute fall and seizure precautions.

  • Administer oral and/or IV calcium supplements as ordered.

  • Encourage calcium-rich foods.

Hypercalcemia Interventions:

  • Monitor V/S, especially HR.

  • Monitor ECG.

  • Encourage increased fluid intake.

  • Increase patient activity, including active range of motion.

Magnesium (Mg2+)

  • Normal Range: 1.5–2.5 mEq/L

  • Function:

    • Found primarily inside cells.

    • Key role in:

    • Production and use of ATP.

    • Regulation of intracellular metabolism by activation of enzymes.

    • Integral part of Na-K pump.

    • Required for synthesis of nucleic acids and proteins.

    • Helps maintain Ca2+ levels.

  • Homeostasis:

    • Reabsorption or excretion by the kidneys.

    • Also absorbed by the intestine.

  • Dietary Sources:

    • Cashews, halibut, Swiss chard and other green leafy vegetables, tofu, wheat germ, dried fruit.

Electrolyte Imbalances: Magnesium

Hypomagnesemia <1.5 mEq/L

  • Causes:

    • Decreased intake.

    • Total Parenteral Nutrition (TPN) without magnesium.

    • Decreased absorption due to:

    • Nasogastric suction.

    • Draining fistulas.

    • Prolonged diarrhea.

    • Laxative abuse.

    • Malabsorption syndrome.

    • Ulcerative colitis.

    • Crohn’s disease.

    • Increased renal excretion:

    • Diuresis.

    • Loop and thiazide diuretics.

Hypermagnesemia >2.5 mEq/L

  • Causes:

    • Excessive intake of magnesium-containing antacids or cathartics.

    • TPN with excessive magnesium.

    • Prolonged use of intravenous magnesium sulfate.

    • Renal failure.

    • Severe dehydration.

    • Adrenal insufficiency.

    • Leukemia.

Hypomagnesemia Clinical Manifestations:

  • Irritable nerves and muscles.

  • Hyperactive deep tendon reflexes.

  • Seizures.

  • Dysrhythmias (especially tachyarrhythmias).

  • ECG changes.

  • Altered level of consciousness.

  • Mood swings, delusions, hallucinations.

  • Dysphagia, nausea, vomiting.

Hypermagnesemia Clinical Manifestations:

  • Warm, flushed appearance.

  • Nausea, vomiting.

  • Drowsiness, lethargy.

  • Decreased muscle strength; generalized weakness.

  • Decreased deep tendon reflexes.

  • Hypotension.

  • Dysrhythmias (especially bradycardia and heart block).

  • Slow, shallow respirations; respiratory arrest.

Hypomagnesemia Interventions:

  • Assess V/S, especially HR.

  • Monitor ECG.

  • Assess mental status, level of consciousness.

  • Monitor laboratory results (potassium and calcium levels).

  • Assess swallowing before administering medications, food, or fluid.

  • Institute seizure precautions.

  • Administer oral or IV supplements as ordered.

Hypermagnesemia Interventions:

  • Assess V/S, especially HR.

  • Monitor ECG.

  • Assess mental status, changes in level of consciousness.

  • Assess neuromuscular strength and activity.

  • Encourage increased oral intake, increased IV fluids.

  • Administer loop diuretics as ordered.

  • Provide respiratory support (supplemental oxygen or mechanical ventilation) as needed.

Chloride (Cl−)

  • Normal Range: 98–106 mEq/L

  • Function:

    • Most abundant anion in the extracellular fluid (ECF).

    • Key role in maintaining serum osmolarity.

    • Required for the formation of stomach acid.

    • Plays a buffering role in acid-base balance.

  • Homeostasis:

    • "Where sodium goes, chloride also goes."

  • Dietary Sources:

    • Seaweed, rye, tomatoes, lettuce, celery, olives.

    • Table salt, salt substitutes.

Electrolyte Imbalances: Chloride

Hypochloremia <98 mEq/L

  • Causes:

    • Overhydration.

    • Heart failure.

    • Syndrome of inappropriate antidiuretic hormone secretion (SIADH).

    • Vomiting or gastric suction.

    • Addison’s disease.

    • Burns.

    • Metabolic alkalosis.

    • Certain medications (aldosterone, bicarbonates, steroids, loop and thiazide diuretics).

  • Clinical Manifestations:

    • Irritable nerves and muscles.

    • Tetany.

    • Hypotension.

    • Shallow breathing.

Hyperchloremia >106 mEq/L

  • Causes:

    • Dehydration.

    • Anemia.

    • Excessive normal saline infusion.

    • Cushing syndrome.

  • Clinical Manifestations:

    • Weakness.

    • Lethargy.

    • Deep breathing.

Hypochloremia Interventions:

  • Monitor V/S, I&O, laboratory results.

  • Restrict water intake.

  • Administer hypertonic IV saline.

Hyperchloremia Interventions:

  • Monitor V/S, level of consciousness (LOC), I&O, laboratory results.

  • Limit salt intake.

  • Increase water intake.

  • Administer hypotonic IV solutions.

Phosphate (PO43−)

  • Normal Range: 2–4.5 mg/dL

  • Function:

    • Most abundant anion in the intracellular fluid (ICF).

    • Helps maintain bone and teeth structure.

    • Plays a key role in cellular metabolism and ATP production.

    • Essential for carbohydrate metabolism.

  • Homeostasis:

    • Inverse relationship with Ca2+ (↑ Ca2+ →↓ PO43−).

    • PTH increases excretion by the kidneys.

  • Dietary Sources:

    • Milk, meat, nuts, legumes, grains.

Electrolyte Imbalances: Phosphate

Hypophosphatemia <2 mg/dL

  • Causes:

    • Abnormal shift into the cell.

    • Hyperventilation.

    • Respiratory alkalosis.

    • Hyperglycemia.

    • Absorption issues from the GI tract (phosphorus-binding antacids).

    • Starvation, malabsorption syndrome.

    • Inadequate vitamin D.

    • Chronic diarrhea, laxative abuse.

    • Increased excretion by kidneys (thiazides and loop diuretics, diabetic ketoacidosis).

    • Hyperparathyroidism, hypocalcemia.

Hyperphosphatemia >4.5 mg/dL

  • Causes:

    • Impaired renal function.

    • Hypoparathyroidism.

    • Acid-base imbalances.

    • Cellular injury.

Hypophosphatemia Clinical Manifestations:

  • Weak pulse.

  • Shallow respirations.

  • Hypotension, Decreased Cardiac Output (CO).

  • Hemolytic anemia.

  • Bleeding, increased bruising.

  • Muscle weakness.

  • Decreased deep tendon reflexes.

  • Tremors.

  • Bone pain.

  • Anorexia.

  • Increased risk for infection.

Hyperphosphatemia Clinical Manifestations:

  • Signs of hypocalcemia (muscle spasms, tetany).

  • Hyperreflexia.

  • Muscle spasms, weakness.

  • Tachycardia.

  • Nausea, diarrhea, cramping.

Hypophosphatemia Interventions:

  • Assess V/S, especially respiratory rate (RR), oxygen saturation (SpO2), and blood pressure (BP).

  • Assess muscle strength and neuromuscular function.

  • Assess for signs of heart failure.

  • Encourage phosphate-rich foods.

  • Instruct patient to avoid phosphorus-binding antacids.

  • Administer oral and IV phosphorus.

  • Administer pain medications.

  • Monitor for signs of infection.

Hyperphosphatemia Interventions:

  • Monitor V/S, I&O.

  • Monitor Laboratories:

    • Serum phosphorus.

    • Serum calcium.

    • Blood Urea Nitrogen (BUN).

    • Creatinine levels.

  • Assess signs of hypocalcemia.

  • Teach patient to avoid phosphorus-rich foods.

Summary Questions

  1. What are 3 things you already knew about today’s lecture content?

  2. What are 2 things you learned today?

  3. What is one question you still have?

References

  • Yoost, B. L., & Crawford, L. R. (2023). Fundamentals of nursing: Active learning for collaborative practice (3rd ed.). Elsevier.

  • Zerwekh, J. (2024). Mosby’s® fluid & electrolytes memory notecards (3rd ed.). Elsevier.