Comprehensive Study Guide to Electrolyte Imbalances: Sodium, Potassium, Calcium, Magnesium, Phosphorus, and Chloride

Sodium ($Na^+$) Imbalance

Sodium imbalances are significantly linked to neurological changes and systemic fluid shifts. The fundamental rule for sodium is “Where Sodium goes, Water flows!”

Comparison of Imbalances

Hyponatremia (< 135\,mEq/L)

Often referred to as “salt loss,” this condition involves a low serum sodium level.

• Physiology: High water levels lead to hemodilution (decreased salt concentration relative to water).

• Two Types of Hyponatremia:

  • Hypovolemic Hyponatremia: Results from a simultaneous decrease in both fluid and sodium levels.

  • Hypervolemic Hyponatremia: Results from increased levels of water in the body, which dilutes existing sodium.

Hypernatremia (> 145\,mEq/L)

Often referred to as “fried salt,” this condition involves a high serum sodium level.

• Physiology: Low water levels lead to hemoconcentration (increased salt concentration relative to water).

• Mechanism: Increased sodium in the vessels leads to increased water retention in the vessels, causing elevated blood pressure and fluid retention.

Risk Factors

For Hypernatremia

• Sodium Intake: High oral ingestion or administration of hypertonic IV fluids.

• Loss of Fluids: Conditions such as fever, severe burns, or Diabetes Insipidus (DI).

For Hyponatremia

• Loss of Sodium: Diaphoresis (sweating), diarrhea, vomiting, drains (NGT suction), and diuretics.

• Fluid Overload/Dilution: Syndrome of Inappropriate Antidiuretic Hormone (SIADH), excessive water intake, or heart failure.

Signs and Symptoms

Hypernatremia (Mnemonics: “FRIED” and “SALT”)

• Skin is dry.

• Agitation.

• Low-grade fever.

• Thirst (dry mucous membranes).

• Flushed skin.

• Restless, anxious, confused, irritable.

• Increased blood pressure and fluid retention.

• Edema (pitting).

• Decreased urine output.

Hyponatremia (Mnemonic: “LALTS”)

• Lethargy (weakness/fatigue).

• Anorexia (nausea/vomiting).

• Limp muscles (muscle weakness).

• Tachycardia (thready pulse).

• Seizures/headache.

• Stomach cramping (hyperactive bowels).

• Orthostatic hypotension.

• Stupor/coma.

Treatment and Interventions

• Underlying Cause: Always treat the underlying condition causing the imbalance.

• For Hypernatremia: Limit sodium intake; administer isotonic or hypotonic IV solutions if the cause is fluid loss.

• For Hyponatremia: Administer hypertonic IV solutions; implement fluid restrictions for SIADH-related overload.

• Safety Precautions:

  • Initiate seizure precautions.

  • Initiate NPO (nothing by mouth) status for airway protection if the patient is lethargic, confused, or comatose to prevent aspiration risk.

Potassium ($K^+$) Imbalance

Potassium imbalances are critical due to their direct effect on cardiac rhythm and muscle contractility.

Comparison of Imbalances

Hypokalemia (< 3.5\,mEq/L)

• Muscle State: Generalized muscle weakness (including smooth muscle in the bronchi and GI system).

• EKG Changes: Think “Low.” Flattened T-waves or T-wave inversion.

Hyperkalemia (> 5\,mEq/L)

• Muscle State: Muscles contract for too long, appearing tight and contracted.

• EKG Changes: Think “High.” Tall, peaked T-waves.

Risk Factors

For Hyperkalemia

• Excess Intake: High potassium IV fluids.

• Adrenal Issues: Adrenal gland insufficiency.

• Blood Chemistry: Acidosis (high acid levels in the blood).

• Medications: NSAIDs (ibuprofen, naproxen) and potassium-sparing diuretics (e.g., spironolactone).

For Hypokalemia

• Low Intake: Inadequate diet or NPO status.

• Fluid Loss: Vomiting, diarrhea, and gastric suction.

• Chemistry: Alkalosis.

• Medications: Potassium-wasting diuretics (loop or thiazide diuretics).

Signs and Symptoms

Hyperkalemia (Mnemonic: “MURDER”)

• Muscle cramps and weakness.

• Urine abnormalities.

• Respiratory distress.

• Decreased cardiac contractility (lowering HR and BP).

• EKG changes.

• Reflexes (decreased Deep Tendon Reflexes/DTR).

Hypokalemia (Mnemonic: “NED HAS MANY STRANGE SYMPTOMS”)

• Nausea/vomiting.

• EKG changes.

• Decreased reflexes.

• Hypotension.

• Muscle weakness.

• Shallow breathing.

• Slowing of the GI system (constipation).

Treatment and Interventions

• Continuous EKG monitoring is required for both as dysrhythmias can be life-threatening.

• For Hyperkalemia: Stop potassium intake; administer IV sodium bicarbonate or IV calcium gluconate.

• For Hypokalemia: Administer oral potassium supplements or IV potassium replacement.

  • Safety Rule: Always dilute IV potassium in fluid. Administer slowly to prevent vein irritation/burning. NEVER administer potassium via IV push.

Calcium ($Ca^{+}$) Imbalance

Calcium levels are managed by parathyroid and thyroid hormones, and have an inverse relationship with phosphorus.

Comparison of Imbalances

Hypocalcemia (< 9\,mg/dL)

• Signs: Leads to neuromuscular irritability (tetany).

Hypercalcemia (> 11\,mg/dL)

• Signs: Acts as a sedative to the skeletal system and can lead to stones.

Risk Factors

For Hypercalcemia

• Absorption/Excretion: Kidney disease or use of thiazide diuretics.

• Hormonal: Hyperparathyroidism and hyperthyroidism.

• Bone Loss: Bone breakdown from metastatic cancer.

• Concentration: Hemoconcentration.

For Hypocalcemia

• Inability to Absorb: GI tract issues.

• Excessive Loss: Diuretics, diarrhea, or wound drainage.

• Kidney Disease: Often involves low Phosphorus and Vitamin D.

Signs and Symptoms

Hypocalcemia (Mnemonic: “CATS GO NUMB”)

• Convulsions/seizures.

• Arrhythmias.

• Tetany.

• Spasm and stridor.

• Numbness in fingers, face, and limbs.

• Positive Trousseau’s Sign: Carpal spasm induced by inflating a blood pressure cuff.

• Positive Chvostek’s Sign: Facial muscle twitching triggered by tapping over the facial nerve (think “C” for Cheesy smile).

Hypercalcemia (Mnemonic: “BACK ME”)

• Bone pain.

• Arrhythmias/cardiac arrest (bounding pulses).

• Constipation.

• Kidney stones (renal calculi) caused by the kidneys' inability to excrete excess calcium.

• Muscle weakness.

• Excessive urination.

Treatment and Interventions

• Safety: Patients with calcium imbalances are at high risk for pathological fractures. Move patients carefully and slowly.

• For Hypercalcemia: Stop calcium intake; administer medications to lower levels (Phosphorus or Calcitonin, which “tones down” blood calcium).

• For Hypocalcemia: Increase dietary calcium and supplements; administer Vitamin D; administer calcium gluconate; initiate seizure precautions.

Magnesium ($Mg$) Imbalance

Magnesium acts primarily as a sedative in the body and tends to rise and fall in tandem with Calcium.

Comparison of Imbalances

Hypomagnesemia (< 1.5\,mg/dL)

• Effect: “High everything – not sedated.”

• Signs: Hyperreflexia, tachycardia, hypertension, shallow respirations, muscle twitching, paresthesias, tetany, seizures, irritability, and confusion.

Hypermagnesemia (> 2.5\,mg/dL)

• Effect: “Low everything – sedated.”

• Signs: Decreased Deep Tendon Reflexes (DTRs), drowsiness/coma, bradycardia, hypotension, bradypnea (leading to respiratory depression), and decreased bowel sounds.

Risk Factors

For Hypermagnesemia

• Intake: Magnesium-containing antacids (TUMS) and laxatives.

• Systemic: Renal insufficiency (decreased excretion) or Diabetic Ketoacidosis (DKA).

For Hypomagnesemia

• Malabsorption: Celiac disease, Crohn’s disease, or malnutrition (vomiting/diarrhea).

• Excretion: Use of diuretics or chronic alcoholism.

• Intracellular Movement: Sepsis, hyperglycemia, and insulin administration.

Treatment and Interventions

• Hypomagnesemia signs identical to calcium include Positive Trousseau’s and Chvostek’s signs.

• For Hypermagnesemia: Administer loop diuretics, calcium chloride, or IV calcium gluconate; limit magnesium intake; avoid laxatives/antacids. Hemodialysis is used in severe cases.

• For Hypomagnesemia: Administer magnesium sulfate (IV or PO); initiate seizure precautions; increase intake of nuts, seeds, legumes, whole grains, and milk.

Phosphorus ($P$) Imbalance

Phosphorus has an inverse relationship with Calcium ($P \propto \frac{1}{Ca^+}$).

Comparison of Imbalances

Hypophosphatemia (< 2.5\,mg/dL)

• Overview: Lower serum phosphorus levels often linked to fluid loss.

Hyperphosphatemia (> 4.5\,mg/dL)

• Overview: Directly linked to Hypocalcemia; often suggests injured kidneys are unable to filter excess phosphate.

Risk Factors

For Hyperphosphatemia

• Kidney: Dysfunction/ESRD.

• Intake: Overuse of enemas or laxatives.

• Cellular: Rhabdomyolysis and Vitamin D toxicity.

• Hormonal: Hypoparathyroidism and Acromegaly.

For Hypophosphatemia

• Excretion: Chronic vomiting/diarrhea (e.g., eating disorders), overconsumption of diuretics, or burns.

• Nutritional: Malnutrition, starvation, ETOH dependency, and Refeeding Syndrome.

Signs and Symptoms

Hyperphosphatemia (Mnemonic: “MICE ALWAYS DIG SILENTLY”)

• Muscle spasms and tetany.

• Arrhythmias.

• Dry nails/skin.

• Seizures.

Hypophosphatemia (Mnemonic: “A LION OFTEN WANDERS”)

• Arrhythmias.

• Loss of appetite.

• Osteoporosis.

• Weakness and fatigue.

Treatment and Interventions

• High-Phosphorus Foods: Red meat, beans, dairy products, nuts, and lentils.

• For Hyperphosphatemia: Decrease dietary phosphorus; use dialysis for ESRD; manage hypertension.

• For Hypophosphatemia: Increase dietary phosphorus; administer oral/IV phosphate; reintroduce nutrients slowly to prevent refeeding syndrome; reduce diuretics; treat the underlying cause of fluid loss (e.g., burns).

Chloride ($Cl$) Imbalance

Chloride has a direct (same) relationship with Sodium level shifts ($Cl \propto Na^+$).

Comparison of Imbalances

Hypochloremia (< 95\,mEq/L)

• Shared Symptoms: Similar to hyponatremia.

Hyperchloremia (> 105\,mEq/L)

• Mechanism: Often due to dehydration or excessive saline administration.

Risk Factors

For Hyperchloremia

• Sodium link: Hypernatremia.

• Intake: Overuse of IV sodium chloride.

• Systemic: Metabolic acidosis, renal damage, or Diabetes Insipidus (DI).

• State: Dehydration (decreased water = increased chloride concentration).

For Hypochloremia

• Fluid Loss: Large volume loss through vomiting, diarrhea, or SIADH.

• Meds/Conditions: Overuse of diuretics, Addison’s disease, metabolic alkalosis, and excessive gastric suction.

• Associated Imbalance: Potassium imbalance.

Signs and Symptoms

Hyperchloremia (Mnemonic: “ALL IGUANAS HAVE EGGS”)

• Arrhythmias.

• Increased fluid retention.

• Hypertension.

• Edema.

Hypochloremia (Mnemonic: “MOM HAS A TOAD AND A FROG”)

• Muscle weakness.

• Hypotension.

• Altered mental status.

• Fatigue.

• Tachycardia.

Treatment and Interventions

• For Hyperchloremia: Limit sodium; increase fluids to flush salt; manage blood glucose; dialysis for renal disease.

• For Hypochloremia: Increase sodium intake; increase oral fluids; administer IV potassium or IV sodium chloride; reduce diuretic use.