Overview
This lecture reviews the roles, normal lab ranges, causes, symptoms, and treatments of sodium, calcium, potassium, and magnesium imbalances, with key points for nursing exams.
Sodium (Na⁺) Imbalances
- Normal range: 136–145 mEq/L
- Hypernatremia (Na⁺ >145): caused by excess intake, Cushing's syndrome, diabetes insipidus; symptoms include thirst, agitation, muscle weakness, GI upset.
- Hypernatremia treatment: correct sodium slowly with hypotonic IV fluids, diuretics, sodium restriction, increased water intake.
- Hyponatremia (Na⁺ <136): caused by diuretics, kidney failure, SIADH, heart failure; symptoms include confusion (esp. elderly), fatigue, nausea/vomiting, headache.
- Hyponatremia treatment: correct sodium slowly with hypertonic IV fluids, encourage sodium intake, restrict fluids.
Calcium (Ca²⁺) Imbalances
- Normal range: 9–10.5 mg/dL
- Hypercalcemia (Ca²⁺ >10.5): caused by hyperparathyroidism, steroids, bone cancer; symptoms include constipation, decreased deep tendon reflexes (DTR), kidney stones, lethargy, weakness.
- Hypercalcemia treatment: 0.9% NaCl IV fluids, calcitonin, dialysis (if severe).
- Hypocalcemia (Ca²⁺ <9): caused by diarrhea, vitamin D deficiency, hypoparathyroidism, thyroidectomy; symptoms include positive Chvostek's and Trousseau's sign, muscle spasms, numbness/tingling, GI upset.
- Hypocalcemia treatment: calcium supplements PO/IV, increase calcium-rich foods.
Potassium (K⁺) Imbalances
- Normal range: 3.5–5 mEq/L
- Hyperkalemia (K⁺ >5): caused by DKA, metabolic acidosis, salt substitutes, kidney failure; symptoms include dysrhythmias (arrhythmias), muscle weakness, numbness/tingling, nausea/vomiting.
- Hyperkalemia treatment: furosemide, Kayexalate, insulin with dextrose, decrease potassium-rich foods.
- Hypokalemia (K⁺ <3.5): caused by diuretics, GI loss, diaphoresis, Cushing’s syndrome, metabolic alkalosis; symptoms include dysrhythmias, muscle weakness/spasm, constipation or ileus.
- Hypokalemia treatment: potassium supplements PO/IV (may be painful), increase potassium-rich foods.
Magnesium (Mg²⁺) Imbalances
- Normal range: 1.3–2.1 mEq/L
- Hypermagnesemia (Mg²⁺ >2.1): caused by kidney disease, too much Mg antacids/laxatives; symptoms include hypotension, lethargy, muscle weakness, decreased DTR, respiratory/cardiac arrest.
- Hypermagnesemia treatment: furosemide, IV calcium for cardiac reversal.
- Hypomagnesemia (Mg²⁺ <1.3): caused by GI loss, diuretics, malnutrition, alcohol abuse; symptoms include dysrhythmias (Torsades de pointes), tachycardia, hypertension, increased DTRs, tremors, seizures.
- Hypomagnesemia treatment: magnesium supplements PO/IV, increase magnesium-rich foods.
Key Terms & Definitions
- Dysrhythmia — abnormal heart rhythm, risk in potassium and magnesium imbalances.
- Chvostek’s sign — facial twitch with cheek tap, indicates hypocalcemia.
- Trousseau’s sign — hand/finger contraction with BP cuff, indicates hypocalcemia.
- Deep tendon reflexes (DTRs) — muscle reflexes checked for neuro function.
- SIADH — syndrome causing excess ADH and fluid retention.
Action Items / Next Steps
- Review and memorize normal electrolyte ranges and main causes/symptoms of imbalances.
- Practice identifying imbalances from lab values.
- Complete any knowledge checks or practice questions on electrolyte imbalances.