Fluid and Electrolyte Imbalances Vocabulary

Vocabulary flashcards covering basic principles, clinical manifestations, and management of fluid and electrolyte imbalances.

Intracellular Fluid (ICF) Volume

The fluid compartment contained inside body cells, comprising approximately $28\,L$ of water.

Interstitial Fluid (IF) Volume

The fluid compartment located between cells and blood vessels, comprising approximately $10\,L$ of water.

Plasma Volume

The liquid component of blood, comprising approximately $3\,L$ of water.

Fluid Weight Calculation

The clinical standard where $1\,L$ of water weighs $2.2\text{ pounds}$ ($1\,kg$); body weight change is an excellent indicator of fluid volume loss or gain.

ICF Electrolyte Profile

Fluid compartment where the prevalent cation is $K^+$ and the prevalent anion is $PO_4^{3-}$.

ECF Electrolyte Profile

Fluid compartment where the prevalent cation is $Na^+$ and the prevalent anion is $Cl^-$.

Diffusion

The passive movement of molecules across a permeable membrane from an area of high concentration to an area of low concentration.

Facilitated Diffusion

A passive movement mechanism that uses a carrier protein to help move molecules across a cell membrane.

Active Transport

A process requiring external energy (such as ATP) in which molecules are moved against their concentration gradient.

Osmosis

The movement of water down its concentration gradient from a region of low solute concentration to high solute concentration across a semipermeable membrane without requiring outside energy.

Osmotic Pressure

The amount of pull required to stop the osmotic flow of water.

Osmolarity

A measurement of the total concentration of solute expressed as $mOsm/L$ of solution.

Osmolality

A measurement of the number of particles expressed as $mOsm/kg$ of water.

Isotonic Solution

A fluid that has the same osmolality as the interior of the cell.

Hypotonic Solution

A fluid in which solutes are less concentrated than in cells (hypoosmolar).

Hypertonic Solution

A fluid in which solutes are more concentrated than in cells (hyperosmolar).

First Spacing

The normal distribution of fluid in the intracellular fluid (ICF) and extracellular fluid (ECF) compartments.

Second Spacing

The abnormal accumulation of interstitial fluid, clinically referred to as edema.

Third Spacing

An abnormal condition where fluid is trapped in a body cavity or space where it is difficult or impossible for it to move back into cells or blood vessels.

Fluid Volume Deficit (FVD)

Also known as hypovolemia; an abnormal loss of body fluids, inadequate fluid intake, or a shift of fluid from plasma to interstitial fluid.

Dehydration

The loss of pure water without a corresponding loss of sodium.

Fluid Volume Excess

Also known as hypervolemia; results from excess fluid intake, abnormal fluid retention, or an interstitial-to-plasma fluid shift, with weight gain as the most common clinical manifestation.

Hypernatremia

High serum sodium resulting from inadequate water intake, excess water loss, or sodium gain; causes hyperosmolality leading to cellular dehydration, with thirst as its primary protection.

Hyponatremia

Low serum sodium resulting from loss of sodium-containing fluids, water excess, or both; causes headache, irritability, confusion, seizures, and coma.

Hyperkalemia

High serum potassium most commonly caused by renal failure, impaired renal excretion, or ICF to ECF shifts; causes life-threatening arrhythmias and tall, peaked T waves on ECG.

Hypokalemia

Low serum potassium caused by increased losses via kidneys or GI tract, ECF to ICF shifts, or low magnesium; causes cardiac manifestations, muscle weakness, and U waves on ECG.

Parathyroid Hormone (PTH)

A hormone that increases calcium levels by increasing bone resorption, GI absorption, and renal tubule reabsorption of calcium.

Calcitonin

A hormone that decreases calcium levels by increasing calcium deposition into bone, increasing renal calcium excretion, and decreasing GI absorption.

Hypercalcemia

High serum calcium levels caused in two-thirds of cases by hyperparathyroidism, as well as cancers; treated with hydration, bisphosphonates, and calcitonin.

Hypocalcemia

Low serum calcium levels characterized by positive Trousseau's or Chvostek's signs, laryngeal stridor, dysphagia, numbness, tingling, and dysrhythmias.

Hyperphosphatemia

High serum $PO_4^{3-}$ caused by kidney injury, excessive intake, or hypoparathyroidism; leads to calcified deposits in soft tissues and symptoms of hypocalcemia.

Hypophosphatemia

Low serum $PO_4^{3-}$ caused by malnourishment, diarrhea, or phosphate-binding antacids; leads to CNS depression, muscle weakness, and osteomalacia.

Hypermagnesemia

High serum magnesium levels caused by renal insufficiency combined with magnesium intake; leads to hypotension, facial flushing, lethargy, and impaired deep tendon reflexes.

Hypomagnesemia

Low serum magnesium levels caused by alcoholism, starvation, or GI losses; resembles hypocalcemia with hyperactive deep tendon reflexes, tremors, and Chvostek's and Trousseau's signs.

D5W

An IV solution that is technically isotonic in the bag but metabolizes dextrose quickly to yield net free water; provides $170\,cal/L$ and helps prevent ketosis.

Normal Saline (0.9% NaCl)

An isotonic IV solution containing slightly more sodium and chloride than ECF; expands ECF and is the only solution used when administering blood.

Lactated Ringer's Solution

An isotonic IV solution containing sodium, potassium, chloride, calcium, and lactate; ideal for expanding ECF in burns or surgery, but contraindicated in liver problems and hyperkalemia.

D10W

A hypertonic IV fluid that provides $340\,kcal/L$ and free water without electrolytes, subject to peripheral infusion concentration limits.

Colloids

IV solutions containing human plasma products or semisynthetics that remain in the vascular space, increase oncotic pressure, and interfere with coagulation factor VII.