Electrolyte Imbalances and Fluid Regulation

Electrolytes

Electrically charged particles (ions) dissolved in body fluids.

Cations

Positively charged ions.

Anions

Negatively charged ions.

Electrolyte balance

Determined by electroneutrality.

Sodium-potassium pump

A mechanism that actively transports Na out of and K into cells.

Hypokalemia

Serum K < 3.5 mEq/L.

Causes of hypokalemia

Diuretics, vomiting, diarrhea, inadequate intake.

Signs of hypokalemia

Weak pulse, muscle cramps, ECG changes (ST depression).

Hyperkalemia

Serum K > 5.0 mEq/L.

Signs of hyperkalemia

Peaked T waves, bradycardia, muscle weakness, paralysis.

Hyponatremia

Na < 135 mEq/L; due to diuretics, GI loss, inadequate intake.

Signs of hyponatremia

Confusion, seizures, muscle weakness.

Hypernatremia

Na > 145 mEq/L; from DI, dehydration, high Na intake.

Signs of hypernatremia

Restlessness, dry skin, irregular reflexes.

Hypocalcemia

Ca < 8.6 mg/dL.

Signs of hypocalcemia

Tetany, Chvostek's & Trousseau's signs, seizures.

Hypercalcemia

Ca > 10.2 mg/dL.

Signs of hypercalcemia

Weakness, bone pain, kidney stones.

Hypomagnesemia

Causes include alcoholism, diarrhea, diuretics, malabsorption.

Signs of hypomagnesemia

Tetany, positive Chvostek's & Trousseau's signs.

Hypermagnesemia

Causes include renal failure, antacids/laxatives with Mg.

Signs of hypermagnesemia

Low reflexes, hypotension, arrhythmias.

Hypochloremia

Caused by vomiting, diuretics; causes twitching, shallow breathing.

Hyperchloremia

Caused by dehydration, TBI; causes weakness, rapid breathing.

Hypophosphatemia

Causes include malnutrition, DKA, alcoholism.

Signs of hypophosphatemia

Muscle weakness, bone pain.

Hyperphosphatemia

Causes include hypoparathyroidism, bone fractures.

Signs of hyperphosphatemia

Signs of hypocalcemia.

Percentage of body weight that is water

60%.

Main compartments of body fluid

Intracellular (40%) and extracellular (20%).

Forces in fluid transport

Hydrostatic pressure, colloid osmotic pressure.

Regulates water intake

Thirst mechanism.

Regulates water output

ADH (antidiuretic hormone).

RAAS

Renin-angiotensin-aldosterone system, regulates BP and fluid balance.

Hypovolemia

Decreased fluid volume (e.g., from hemorrhage or dehydration).

Hypervolemia

Increased fluid volume (e.g., from heart failure or renal failure).

Cirrhosis pathophysiology

Hepatocyte damage + altered blood flow leading to ascites, sodium retention.

Signs of dehydration

Dry mucous membranes, low urine output, sunken eyes.

Hypoparathyroidism

Caused by impaired PTH secretion leading to low calcium levels.

diet for hypokalemia

potatoes, dried fruit, nuts, cantaloupe, mets, mushroom, carrots, chocolate

diet for hyponatrimia

bacon, butter, canned food, luncheon meats, table salt

diet for hypokalemia

cheese, milk, soy milk, sardines, spinach, tofu, low-fat yogurt

hypomagnesium diet

oranges, peanut butter, chocolate, nuts

hypochloremia diet

seaweed, rye, tomatoes, lettuce, celery, olives

hypophosphatemia diet

meat, poltry, legumes, garlic, dried fruit, potatoes, fish, egg, dairy products

Sodium (Na⁺) – Normal Range

135–145 mEq/L

Hyponatremia (

Symptoms: Confusion, seizures, hypotension, muscle cramps

Hypernatremia (>145)

Symptoms: Thirst, dry skin, restlessness, ↓ DTRs

Potassium (K⁺) – Normal Range

3.5–5.0 mEq/L

Hypokalemia (

Symptoms: Leg cramps, flat T waves, ↓ DTRs, weak pulse

Hyperkalemia (>5.0)

Symptoms: Peaked T waves, flaccid paralysis, bradycardia

Chloride (Cl⁻) – Normal Range

98–106 mEq/L

Hypochloremia (

Symptoms: Shallow breathing, muscle twitching, confusion

Hyperchloremia (>108)

Symptoms: Rapid breathing, weakness, cardiac arrest

Calcium (Ca²⁺) – Normal Range

8.5–10.5 mg/dL

Hypocalcemia (

Symptoms: Tetany, +Chvostek/Trousseau, seizures, ↑ DTRs

Hypercalcemia (>10.5)

Symptoms: Bone pain, ↓ DTRs, constipation, renal stones

Magnesium (Mg²⁺) – Normal Range

1.5–2.5 mEq/L

Hypomagnesemia (

Symptoms: ↑ DTRs, tetany, +Chvostek/Trousseau, seizures

Hypermagnesemia (>2.5)

Symptoms: ↓ DTRs, flaccid paralysis, hypotension, bradycardia

Phosphate (PO₄³⁻) – Normal Range

2.5–4.5 mg/dL

Hypophosphatemia (

Symptoms: Muscle weakness, tremors, bone pain

Hyperphosphatemia (>4.5)

Symptoms: Tetany, soft tissue calcifications, confusion

Sodium (Na⁺)

135–145 mEq/L

Potassium (K⁺)

3.5–5.0 mEq/L

Calcium (Ca²⁺)

8.5–10.5 mg/dL

Magnesium (Mg²⁺)

1.5–2.5 mEq/L

Phosphate (PO₄³⁻)

2.5–4.5 mg/dL

Chloride (Cl⁻)

98–106 mEq/L