Fluid, Electrolyte, and Thermoregulation
Concepts in Nursing Care: Assessment,
Imbalances, and Clinical Management.
Intracellular Fluid (ICF)
2/3 of total body water, inside cells, high in K+ and phosphate.
Extracellular Fluid (ECF)
1/3 of total body water, includes interstitial fluid, plasma (intravascular), and transcellular fluid.
High in Na+ and Cl-.
Functions of Body Fluids
Transport nutrients, regulate temperature, maintain blood volume, remove waste.
Osmosis
Water moves from low solute concentration to high.
Diffusion
Solutes move from high to low concentration.
Filtration
Hydrostatic pressure pushes fluid out of capillaries.
Active Transport
Requires ATP to move substances against the concentration gradient (e.g., Na+/K+ pump).
Sodium (Na⁺)
Normal Range: 135-145 mEq/L; Function: Nerve/muscle function, fluid balance; Signs of
Imbalance: Hyponatremia: Confusion, seizures, weakness, nausea. Hypernatremia: Thirst, dry
mucosa, confusion.
Potassium (K⁺)
Normal Range: 3.5-5.0 mEq/L; Function: Muscle/heart contraction; Signs of Imbalance:
Hypokalemia: Weakness, arrhythmias, cramps. Hyperkalemia: Peaked T waves, cardiac arrest.
Calcium (Ca²⁺)
, Normal Range: 8.6-10.2 mg/dL; Function: Bone health, muscle function; Signs of Imbalance:
Hypocalcemia: Tetany, Chvostek's & Trousseau's signs, spasms. Hypercalcemia: Lethargy, kidney
stones.
Magnesium (Mg²⁺)
Normal Range: 1.3-2.3 mEq/L; Function: Neuromuscular function; Signs of Imbalance:
Hypomagnesemia: Seizures, tremors. Hypermagnesemia: Hypotension, bradycardia.
Phosphate (PO4³⁻)
Normal Range: 2.5-4.5 mg/dL; Function: ATP production, bone health; Signs of Imbalance:
Hypophosphatemia: Muscle weakness, confusion. Hyperphosphatemia: Tetany, soft tissue
calcifications.
Chloride (Cl⁻)
Normal Range: 97-107 mEq/L; Function: Acid-base balance; Signs of Imbalance: Hypochloremia:
Alkalosis, muscle spasms. Hyperchloremia: Acidosis, dehydration.
Dehydration
Water loss without electrolyte loss. Signs: Dry mucous membranes, poor skin turgor,
tachycardia.
Fluid Volume Deficit (FVD)
Water and electrolyte loss. Signs: Hypotension, increased HR, decreased urine output.
Fluid Overload (Hypervolemia)
Excess fluid in ECF. Signs: Edema, crackles in lungs, JVD, weight gain.
Isotonic IV Fluids
Examples: NS (0.9% NaCl), LR; Uses: Increases intravascular volume (for dehydration, blood
loss).
Hypotonic IV Fluids
Example: 0.45% NaCl; Uses: Moves fluid into cells (for DKA, hypernatremia).
Hypertonic IV Fluids
Examples: 3% NaCl, D5W in NS; Uses: Pulls fluid into vascular space (for cerebral edema,
hyponatremia).
Hypokalemia
Concepts in Nursing Care: Assessment,
Imbalances, and Clinical Management.
Intracellular Fluid (ICF)
2/3 of total body water, inside cells, high in K+ and phosphate.
Extracellular Fluid (ECF)
1/3 of total body water, includes interstitial fluid, plasma (intravascular), and transcellular fluid.
High in Na+ and Cl-.
Functions of Body Fluids
Transport nutrients, regulate temperature, maintain blood volume, remove waste.
Osmosis
Water moves from low solute concentration to high.
Diffusion
Solutes move from high to low concentration.
Filtration
Hydrostatic pressure pushes fluid out of capillaries.
Active Transport
Requires ATP to move substances against the concentration gradient (e.g., Na+/K+ pump).
Sodium (Na⁺)
Normal Range: 135-145 mEq/L; Function: Nerve/muscle function, fluid balance; Signs of
Imbalance: Hyponatremia: Confusion, seizures, weakness, nausea. Hypernatremia: Thirst, dry
mucosa, confusion.
Potassium (K⁺)
Normal Range: 3.5-5.0 mEq/L; Function: Muscle/heart contraction; Signs of Imbalance:
Hypokalemia: Weakness, arrhythmias, cramps. Hyperkalemia: Peaked T waves, cardiac arrest.
Calcium (Ca²⁺)
, Normal Range: 8.6-10.2 mg/dL; Function: Bone health, muscle function; Signs of Imbalance:
Hypocalcemia: Tetany, Chvostek's & Trousseau's signs, spasms. Hypercalcemia: Lethargy, kidney
stones.
Magnesium (Mg²⁺)
Normal Range: 1.3-2.3 mEq/L; Function: Neuromuscular function; Signs of Imbalance:
Hypomagnesemia: Seizures, tremors. Hypermagnesemia: Hypotension, bradycardia.
Phosphate (PO4³⁻)
Normal Range: 2.5-4.5 mg/dL; Function: ATP production, bone health; Signs of Imbalance:
Hypophosphatemia: Muscle weakness, confusion. Hyperphosphatemia: Tetany, soft tissue
calcifications.
Chloride (Cl⁻)
Normal Range: 97-107 mEq/L; Function: Acid-base balance; Signs of Imbalance: Hypochloremia:
Alkalosis, muscle spasms. Hyperchloremia: Acidosis, dehydration.
Dehydration
Water loss without electrolyte loss. Signs: Dry mucous membranes, poor skin turgor,
tachycardia.
Fluid Volume Deficit (FVD)
Water and electrolyte loss. Signs: Hypotension, increased HR, decreased urine output.
Fluid Overload (Hypervolemia)
Excess fluid in ECF. Signs: Edema, crackles in lungs, JVD, weight gain.
Isotonic IV Fluids
Examples: NS (0.9% NaCl), LR; Uses: Increases intravascular volume (for dehydration, blood
loss).
Hypotonic IV Fluids
Example: 0.45% NaCl; Uses: Moves fluid into cells (for DKA, hypernatremia).
Hypertonic IV Fluids
Examples: 3% NaCl, D5W in NS; Uses: Pulls fluid into vascular space (for cerebral edema,
hyponatremia).
Hypokalemia
