Electrolyte Management – Critical & Emergency Care Nursing

80 vocabulary flashcards summarizing essential electrolyte terms, disorders, mechanisms, diagnostics, and treatments from the lecture notes.

Electrolyte

A substance that dissociates into ions in solution and can conduct electricity (includes salts, acids, bases).

Cation

Positively charged ion (e.g., Na⁺, K⁺, Ca²⁺).

Anion

Negatively charged ion (e.g., Cl⁻, HCO₃⁻, PO₄³⁻).

Extracellular Fluid (ECF)

Fluid outside cells; major cation Na⁺, major anion Cl⁻.

Intracellular Fluid (ICF)

Fluid inside cells; major cation K⁺, major anion PO₄³⁻.

Sodium (Na⁺)

Primary ECF cation; normal serum 135–145 mEq/L; regulates water balance, acid-base status, nerve & muscle function.

Hypernatremia

Serum Na⁺ > 145 mEq/L; hypertonic state classified as hypovolemic, isovolemic, or hypervolemic.

Hyponatremia

Serum Na⁺ < 135 mEq/L; usually hypotonic, classified as hypo-, iso-, or hypervolemic; may be hypertonic if other solutes high.

Chloride (Cl⁻)

Primary ECF anion; normal serum 97–110 mEq/L; maintains electroneutrality with Na⁺ and inverse to HCO₃⁻.

Hyperchloremia

Serum Cl⁻ > 110 mEq/L; often with metabolic acidosis; causes: excess NaCl, diarrhea, renal disease.

Hypochloremia

Serum Cl⁻ < 97 mEq/L; often with metabolic alkalosis; causes: vomiting, diuretics, CF.

Potassium (K⁺)

Major ICF cation; normal serum 3.5–5.0 mEq/L; crucial for resting membrane potential and cardiac rhythm.

Hyperkalemia

Serum K⁺ > 5.0 mEq/L; results from increased intake, ICF→ECF shift, or renal failure.

Hypokalemia

Serum K⁺ < 3.5 mEq/L; due to poor intake, GI/renal loss, alkalosis, insulin/β-agonists.

Magnesium (Mg²⁺)

Predominantly intracellular cation; normal serum 1.3–2.1 mEq/L; cofactor for Na⁺/K⁺-ATPase, neuromuscular stability.

Hypermagnesemia

Serum Mg²⁺ > 2.1 mEq/L; usually from renal failure or excessive antacids; causes weakness, bradycardia, ↓DTRs.

Hypomagnesemia

Serum Mg²⁺ < 1.3 mEq/L; from malnutrition, alcoholism, diuretics; leads to hyperreflexia, torsades de pointes.

Calcium (Ca²⁺)

Cation in bone & serum; total 9–10.5 mg/dL; ionized 4.5–5.6 mg/dL; needed for threshold potential, clotting, bones.

Hypercalcemia

Serum Ca²⁺ > 10.5 mg/dL (ionized > 5.6); causes: hyperparathyroidism, malignancy, excess vitamin D.

Hypocalcemia

Serum Ca²⁺ < 9 mg/dL (ionized < 4.5); causes: vitamin D deficiency, hypoparathyroidism, blood transfusions.

Phosphate (PO₄³⁻)

ICF anion; normal serum 3–4.5 mg/dL; essential for ATP, acid-base buffering, inverse to calcium.

Hyperphosphatemia

Serum PO₄³⁻ > 4.5 mg/dL; from renal failure, cell lysis, hypoparathyroidism; leads to hypocalcemia & calcifications.

Hypophosphatemia

Serum PO₄³⁻ < 3 mg/dL; due to malabsorption, alcohol, refeeding, alkalosis; causes muscle weakness, ↓O₂ delivery.

Resting Membrane Potential (RMP)

Stable transmembrane voltage of a cell, mainly maintained by K⁺ gradient.

Action Potential

Rapid change in membrane voltage generated when threshold is reached, allowing nerve/muscle impulse.

Threshold Potential

Membrane voltage that must be reached to trigger an action potential; raised by hypercalcemia, lowered by hypocalcemia.

Aldosterone

Adrenal cortex hormone promoting renal Na⁺ reabsorption and K⁺ excretion.

Antidiuretic Hormone (ADH)

Posterior pituitary hormone that promotes renal water reabsorption; excess → dilutional hyponatremia.

Natriuretic Peptides

Cardiac hormones that promote renal Na⁺ & water excretion, opposing RAAS.

Syndrome of Inappropriate ADH (SIADH)

Excess ADH secretion causing isovolemic hyponatremia and concentrated urine.

Diabetes Insipidus (DI)

ADH deficiency/resistance → polyuria, polydipsia, isovolemic hypernatremia.

Na⁺/K⁺-ATPase Pump

Cell membrane pump exchanging 3 Na⁺ out / 2 K⁺ in, maintaining gradients and RMP.

Total Body Water (TBW)

Sum of water in body; used to calculate free water deficit in hypernatremia.

Serum Osmolality

Concentration of solutes in plasma; normal 275–295 mOsm/kg; ↑ in dehydration or hypernatremia.

Urine Specific Gravity

Measure of urine concentration; high (> 1.030) suggests water deficit, low in DI.

Hematocrit (Hct)

Percentage of blood volume occupied by RBCs; rises with dehydration.

Kussmaul Breathing

Deep, rapid respirations seen in metabolic acidosis (e.g., hyperchloremia).

Postural Hypotension

Drop in BP on standing; sign of hypovolemia such as water deficit hypernatremia.

Jugular Vein Distention (JVD)

Visible neck vein fullness; sign of hypervolemia (e.g., sodium excess).

Desmopressin

Synthetic ADH analog used to treat central DI and some hypernatremia cases.

Free Water Deficit

Volume of water needed to correct hypernatremia; TBW × [(Serum Na/140) – 1].

Calcitonin

Thyroid hormone lowering serum Ca²⁺ by inhibiting bone resorption & increasing renal excretion.

Parathyroid Hormone (PTH)

Hormone raising serum Ca²⁺ and lowering phosphate by bone resorption & renal effects.

Vitamin D

Fat-soluble steroid that increases GI absorption of Ca²⁺ & phosphate.

2,3-DPG

Red-cell compound that facilitates oxygen release to tissues; depends on phosphate levels.

QT Interval

EKG measure of ventricular depolarization/repolarization; shortened in hypercalcemia, prolonged in hypocalcemia/magnesemia.

Trousseau’s Sign

Carpal spasm triggered by BP cuff inflation, indicating hypocalcemia.

Chvostek’s Sign

Facial muscle twitch when tapping facial nerve; suggests hypocalcemia.

Kayexalate (Sodium Polystyrene Sulfonate)

Cation-exchange resin used to remove K⁺ via GI tract in hyperkalemia.

Dialysis

Renal replacement therapy that removes excess electrolytes & toxins from blood.

Loop Diuretic

Drug (e.g., furosemide) inhibiting Na-K-2Cl in Loop of Henle; treats hypervolemia, hypercalcemia, hypernatremia.

Potassium-Sparing Diuretic

Agent (e.g., spironolactone) that blocks aldosterone or Na⁺ channels, risking hyperkalemia.

Bisphosphonates

Drugs inhibiting bone resorption; used for hypercalcemia of malignancy.

Denosumab

Monoclonal antibody against RANKL reducing bone resorption; treats refractory hypercalcemia.

Osmotic Demyelination Syndrome

Neurologic injury from rapid correction of hyponatremia; limit Na⁺ rise ≤ 10–12 mEq/L per 24 h.

Osmotic Diuresis

Water loss caused by unreabsorbed solutes (e.g., glucose, mannitol) leading to hypovolemic hypernatremia.

U Wave

EKG wave appearing in hypokalemia, following the T wave.

Torsades de Pointes

Polymorphic VTach associated with prolonged QT; seen in hypomagnesemia.

Refeeding Syndrome

Rapid infusion of carbs in malnourished patients causing sudden PO₄³⁻ drop, leading to hypophosphatemia.

Phosphate Binders

Agents (e.g., calcium carbonate) that reduce GI phosphate absorption in hyperphosphatemia.