FLUID AND ELECTROLYTE BALANCE KEY CONCEPTS FOR EXAM 1
REVIEW
Maintaining the appropriate balance of water and electrolytes within the body's fluid compartments
(intracellular and extracellular) is essential for normal cellular function and overall homeostasis.
Imbalances can significantly impact various physiological processes.
Electrolytes:
Sodium (Na⁺) – Think Brain
• Primary extracellular cation.
• Functions: Regulates fluid balance, blood volume, blood pressure, nerve impulse
transmission, and muscle contraction.
• Imbalances:
• Hyponatremia: < 135 mEq/L.
o Causes: SIADH (syndrome of inappropriate antidiuretic hormone), Diuretics
(especially thiazides), vomiting, diarrhea, excessive sweating, CHF (congestive
heart failure), renal failure
o Signs: Decreased serum osmolality, edema (in hypervolemic-
hyponatremia), hyporeflexia
o Symptoms: Nausea/vomiting, headache, lethargy, muscle cramps
o Clinical Manifestations: Seizures, cerebral edema (in acute, severe cases), coma
• Hypernatremia: > 145 mEq/L.
o Causes: Dehydration (sodium loss -> water loss), diabetes insipidus, osmotic
diuresis (hyperglycemia)
o Signs: Dry mucous membranes, decreased skin turgor, increased serum
osmolality, hyperreflexia (in severe cases)
o Symptoms: Thirst, fatigue, confusion, irritability
o Clinical Manifestations: Seizures, lethargy, coma, intracranial hemorrhage
(sever hypernatremia)
Potassium (K⁺) – Think Heart
• Primary intracellular cation.
• Functions: Crucial for maintaining resting membrane potential, nerve impulse transmission,
muscle contraction (especially cardiac muscle), and fluid balance.
• Imbalances:
• Hypokalemia: < 3.5 mEq/L.
o Causes: Diuretics (loop or thiazide), vomiting, diarrhea, inadequate potassium
intake, hyperaldosteronism.
o Signs: ECG changes – flattened T waves. Hyporeflexia (reduced reflexes)
o Symptoms: Muscle weakness, cramps, fatigue, polyuria (increased urination)
, o Clinical Manifestations: Cardiac arrhythmias (atrial fibrillation, ventricular
tachycardia) severe muscle weakness leading to paralysis.
• Hyperkalemia: > 5.0 mEq/L.
o Causes: Kidney failure, Addison’s disease, potassium-sparing diuretics,
tissue injury (trauma, burns, hemolysis)
o Signs: ECG changes – Peaked T waves
o Symptoms: Muscle weakness, fatigue, paresthesia (tingling or numbness)
nausea, abdominal cramping
o Clinical Manifestations: Cardiac arrhythmias (ventricular fibrillation, asystole)
progression to cardiac arrest in severe cases, respiratory muscle paralysis in
extreme cases
Calcium (Ca²⁺) – Think Muscle/Bones
• Functions: Essential for bone mineralization, muscle contraction, nerve impulse
transmission, blood clotting, and enzyme activation.
• Imbalances:
• Hypocalcemia: < 8.5 mg/dL.
o Causes: Hypoparathyroidism, vitamin D deficiency, chronic kidney disease,
magnesium deficiency, pancreatitis
o Signs: Positive Chvostek’s sign (facial twitching when tapping facial nerve),
Positive Trousseau’s sign (carpal spasm with BP cuff inflation), ECG
changes – prolonged QT interval
o Symptoms: Muscle spasms or cramps, Paresthesia (around mouth, fingers,
or toes), fatigue, tetany (severe muscle contractions)
o Clinical Manifestations: Life-threatening laryngospasm, cardiac arrhythmias
(torsades de pointes), cataracts in chronic cases, osteomalacia (in prolonged
hypocalcemia due to vitamin d deficiency)
• Hypercalcemia: > 10.2 mg/dL.
o Causes: Hyperparathyroidism, malignancies (cancers with bone metastasis),
Diuretics (Thiazide), prolonged immobilization, excessive vitamin d or calcium
supplementation
o Signs: ECG changes – Shortened QT interval, dehydration (due to polyuria),
kidney stones
o Symptoms: Muscle weakness, lethargy, nausea/vomiting, constipation, bone pain
o Clinical Manifestations: Confusion, polyuria, cardiac arrhythmias
(bradycardia, heart block), osteoporosis or fractures in chronic cases
, Magnesium (Mg²⁺)
• Functions: Plays a vital role in muscle and nerve function, enzyme activity, protein
synthesis, and carbohydrate metabolism. It's also important for maintaining normal
potassium levels.
• Imbalances:
• Hypomagnesemia: < 1.7 mg/dL.
o Causes: Chronic alcoholism, malnutrition/malabsorption, prolonged diarrhea,
diuretics (loop or thiazides)
o Signs: Positive Chvostek’s sign (facial twitching when tapping facial nerve)
Positive Trousseau’s sign (carpal spasm with BP cuff inflation),
Hyperreflexia, ECG changes – prolonged QT interval
o Symptoms: Muscle cramps, fatigue, tremors
o Clinical Manifestations: Cardiac arrhythmias (torsades de pointes), seizures,
increased risk of hypokalemia and hypocalcemia
• Hypermagnesemia: > 2.2 mg/dL.
o Causes: Renal failure, excessive magnesium intake (antacids or laxatives),
Addison’s disease
o Signs: Hypotension, bradycardia, decreased deep tendon reflexes, ECG
changes – prolonged PR interval and widened QRS
o Symptoms: Lethargy, nausea, weakness
o Clinical Manifestations: Respiratory depression, paralysis, cardiac arrest (in severe
cases)
Chloride (Cl⁻)
• Primary extracellular anion.
• Functions: Maintains fluid balance, assists in gastric acid production, and plays a role in
acid-base balance.
• Imbalances:
• Hypochloremia: > 97 mEq/L
o Causes: Vomiting or gastric suctioning, diuretics, Addison’s disease, metabolic
alkalosis
o Signs: Hypotension, muscle twitching
o Symptoms: Irritability, muscle cramps, fatigue
o Clinical Manifestations: Respiratory depression (due to associated alkalosis),
seizures
• Hyperchloremia: > 107 mEq/L
o Causes: Dehydration, Hypernatremia, Metabolic acidosis, excessive saline
administration
o Signs: Tachypnea (due to metabolic acidosis), Hypertension
o Symptoms: Fatigue, weakness, headache
o Clinical Manifestations: Kussmaul breathing (compensation for acidosis),
arrhythmias (in severe cases)
REVIEW
Maintaining the appropriate balance of water and electrolytes within the body's fluid compartments
(intracellular and extracellular) is essential for normal cellular function and overall homeostasis.
Imbalances can significantly impact various physiological processes.
Electrolytes:
Sodium (Na⁺) – Think Brain
• Primary extracellular cation.
• Functions: Regulates fluid balance, blood volume, blood pressure, nerve impulse
transmission, and muscle contraction.
• Imbalances:
• Hyponatremia: < 135 mEq/L.
o Causes: SIADH (syndrome of inappropriate antidiuretic hormone), Diuretics
(especially thiazides), vomiting, diarrhea, excessive sweating, CHF (congestive
heart failure), renal failure
o Signs: Decreased serum osmolality, edema (in hypervolemic-
hyponatremia), hyporeflexia
o Symptoms: Nausea/vomiting, headache, lethargy, muscle cramps
o Clinical Manifestations: Seizures, cerebral edema (in acute, severe cases), coma
• Hypernatremia: > 145 mEq/L.
o Causes: Dehydration (sodium loss -> water loss), diabetes insipidus, osmotic
diuresis (hyperglycemia)
o Signs: Dry mucous membranes, decreased skin turgor, increased serum
osmolality, hyperreflexia (in severe cases)
o Symptoms: Thirst, fatigue, confusion, irritability
o Clinical Manifestations: Seizures, lethargy, coma, intracranial hemorrhage
(sever hypernatremia)
Potassium (K⁺) – Think Heart
• Primary intracellular cation.
• Functions: Crucial for maintaining resting membrane potential, nerve impulse transmission,
muscle contraction (especially cardiac muscle), and fluid balance.
• Imbalances:
• Hypokalemia: < 3.5 mEq/L.
o Causes: Diuretics (loop or thiazide), vomiting, diarrhea, inadequate potassium
intake, hyperaldosteronism.
o Signs: ECG changes – flattened T waves. Hyporeflexia (reduced reflexes)
o Symptoms: Muscle weakness, cramps, fatigue, polyuria (increased urination)
, o Clinical Manifestations: Cardiac arrhythmias (atrial fibrillation, ventricular
tachycardia) severe muscle weakness leading to paralysis.
• Hyperkalemia: > 5.0 mEq/L.
o Causes: Kidney failure, Addison’s disease, potassium-sparing diuretics,
tissue injury (trauma, burns, hemolysis)
o Signs: ECG changes – Peaked T waves
o Symptoms: Muscle weakness, fatigue, paresthesia (tingling or numbness)
nausea, abdominal cramping
o Clinical Manifestations: Cardiac arrhythmias (ventricular fibrillation, asystole)
progression to cardiac arrest in severe cases, respiratory muscle paralysis in
extreme cases
Calcium (Ca²⁺) – Think Muscle/Bones
• Functions: Essential for bone mineralization, muscle contraction, nerve impulse
transmission, blood clotting, and enzyme activation.
• Imbalances:
• Hypocalcemia: < 8.5 mg/dL.
o Causes: Hypoparathyroidism, vitamin D deficiency, chronic kidney disease,
magnesium deficiency, pancreatitis
o Signs: Positive Chvostek’s sign (facial twitching when tapping facial nerve),
Positive Trousseau’s sign (carpal spasm with BP cuff inflation), ECG
changes – prolonged QT interval
o Symptoms: Muscle spasms or cramps, Paresthesia (around mouth, fingers,
or toes), fatigue, tetany (severe muscle contractions)
o Clinical Manifestations: Life-threatening laryngospasm, cardiac arrhythmias
(torsades de pointes), cataracts in chronic cases, osteomalacia (in prolonged
hypocalcemia due to vitamin d deficiency)
• Hypercalcemia: > 10.2 mg/dL.
o Causes: Hyperparathyroidism, malignancies (cancers with bone metastasis),
Diuretics (Thiazide), prolonged immobilization, excessive vitamin d or calcium
supplementation
o Signs: ECG changes – Shortened QT interval, dehydration (due to polyuria),
kidney stones
o Symptoms: Muscle weakness, lethargy, nausea/vomiting, constipation, bone pain
o Clinical Manifestations: Confusion, polyuria, cardiac arrhythmias
(bradycardia, heart block), osteoporosis or fractures in chronic cases
, Magnesium (Mg²⁺)
• Functions: Plays a vital role in muscle and nerve function, enzyme activity, protein
synthesis, and carbohydrate metabolism. It's also important for maintaining normal
potassium levels.
• Imbalances:
• Hypomagnesemia: < 1.7 mg/dL.
o Causes: Chronic alcoholism, malnutrition/malabsorption, prolonged diarrhea,
diuretics (loop or thiazides)
o Signs: Positive Chvostek’s sign (facial twitching when tapping facial nerve)
Positive Trousseau’s sign (carpal spasm with BP cuff inflation),
Hyperreflexia, ECG changes – prolonged QT interval
o Symptoms: Muscle cramps, fatigue, tremors
o Clinical Manifestations: Cardiac arrhythmias (torsades de pointes), seizures,
increased risk of hypokalemia and hypocalcemia
• Hypermagnesemia: > 2.2 mg/dL.
o Causes: Renal failure, excessive magnesium intake (antacids or laxatives),
Addison’s disease
o Signs: Hypotension, bradycardia, decreased deep tendon reflexes, ECG
changes – prolonged PR interval and widened QRS
o Symptoms: Lethargy, nausea, weakness
o Clinical Manifestations: Respiratory depression, paralysis, cardiac arrest (in severe
cases)
Chloride (Cl⁻)
• Primary extracellular anion.
• Functions: Maintains fluid balance, assists in gastric acid production, and plays a role in
acid-base balance.
• Imbalances:
• Hypochloremia: > 97 mEq/L
o Causes: Vomiting or gastric suctioning, diuretics, Addison’s disease, metabolic
alkalosis
o Signs: Hypotension, muscle twitching
o Symptoms: Irritability, muscle cramps, fatigue
o Clinical Manifestations: Respiratory depression (due to associated alkalosis),
seizures
• Hyperchloremia: > 107 mEq/L
o Causes: Dehydration, Hypernatremia, Metabolic acidosis, excessive saline
administration
o Signs: Tachypnea (due to metabolic acidosis), Hypertension
o Symptoms: Fatigue, weakness, headache
o Clinical Manifestations: Kussmaul breathing (compensation for acidosis),
arrhythmias (in severe cases)
