Electrolyte Imbalances – Notes

Electrolyte Imbalances – Notes

Sodium (Na⁺)

• Normal range: 136–145 mEq/L

• Functions: Fluid balance, nerve/muscle function

Hypernatremia (>145):

• Causes: Excess sodium intake, Cushing’s, diabetes insipidus

• S/S: Thirst, agitation, muscle weakness, GI upset

• Tx: Correct slowly with hypotonic fluids (0.45% NaCl), diuretics (furosemide), restrict sodium, ↑ water

Hyponatremia (<136):

• Causes: Diuretics, kidney failure, SIADH, heart failure

• S/S: Confusion (esp. elderly), fatigue, N/V, headache

• Tx: Hypertonic fluids (2–3% NaCl), ↑ sodium intake, fluid restriction

Calcium (Ca²⁺)

• Normal range: 9–10.5 mg/dL

• Functions: Bones/teeth, nerve/muscle function, clotting

Hypercalcemia (>10.5):

• Causes: Hyperparathyroidism, corticosteroids, bone cancer

• S/S: Constipation, ↓ DTRs, kidney stones, lethargy, weakness

• Tx: IV 0.9% NaCl, calcitonin, dialysis if severe

Hypocalcemia (<9):

• Causes: Diarrhea, Vit D deficiency, hypoparathyroidism, post-thyroidectomy

• S/S: Positive Chvostek’s (cheek twitch) & Trousseau’s (BP cuff hand spasm), muscle spasms, numbness/tingling, GI upset

• Tx: Ca²⁺ supplements (PO/IV), ↑ calcium-rich foods

Potassium (K⁺)

• Normal range: 3.5–5 mEq/L (mnemonic: bananas come in 3–5, or a 5K ≈ 3.2 mi)

• Functions: ICF balance, nerve/muscle function

Hyperkalemia (>5):

• Causes: DKA, metabolic acidosis, kidney failure, salt substitutes

• S/S: Dysrhythmias, muscle weakness, numbness/tingling, N/V

• Tx: Furosemide, Kayexalate, insulin + dextrose (shifts K⁺ into cells), ↓ K⁺ intake

Hypokalemia (<3.5):

• Causes: Diuretics (furosemide), GI loss (vomiting, suction), diaphoresis, Cushing’s, metabolic alkalosis

• S/S: Dysrhythmias, muscle weakness/spasms, constipation, ileus

• Tx: K⁺ supplements (PO/IV with lidocaine if painful), ↑ K⁺ foods (bananas, potatoes, cantaloupe)

Magnesium (Mg²⁺)

• Normal range: 1.3–2.1 mEq/L (mnemonic: MG car fits 1–2 people)

• Functions: Muscle/nerve function, biochemical reactions

Hypermagnesemia (>2.1):

• Causes: Kidney disease, excess Mg-containing antacids/laxatives

• S/S: Hypotension, lethargy, weakness, ↓ DTRs, respiratory/cardiac arrest

• Tx: Furosemide, Ca²⁺ to reverse cardiac effects

Hypomagnesemia (<1.3):

• Causes: GI losses, diuretics, malnutrition, alcohol abuse

• S/S: Dysrhythmias (torsades de pointes), tachycardia, hypertension, ↑ DTRs, tremors, seizures

• Tx: Mg²⁺ supplements (PO/IV), ↑ Mg-rich foods

Knowledge Check (Quiz Recap)

1. Positive Chvostek’s & Trousseau’s → Hypocalcemia

2. Electrolyte imbalance → dysrhythmias (both hyperkalemia & hypokalemia)

3. Hypomagnesemia causes ↑ DTRs & hypertension (not ↓ DTRs/hypotension)