Malaysia
Search
Sign In
Change Password
Points
Sign Out
Hyponatremia Signs and Symptoms
Definition
- Serum sodium concentration <135 mEq/L due to failure of normal water excretion
- Severe hyponatremia is when there is <120 mEq/L serum sodium concentration
Etiology
- Most common causes are medication effects, fluid retention and syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Signs and Symptoms
- Commonly, patients with hyponatremia are asymptomatic and it is only an incidental finding
- Gradual decrease in sodium usually shows minimal symptoms whereas rapid decreases manifest severe symptoms
- Severe symptoms are due to brain edema and increased intracranial pressure
- Mild to moderate symptoms that are relatively nonspecific and occur most commonly in patients with severe chronic hyponatremia are the following:
- Headache
- Fatigue
- Lethargy
- Nausea and vomiting
- Dizziness
- Gait disturbances
- Forgetfulness
- Confusion
- Muscle cramps
- Severe symptoms include seizures, obtundation, coma and respiratory arrest
- Acute intervention is needed if the following symptoms occur:
- Polydipsia
- Muscle cramps
- Headaches
- Falls
- Confusion
- Altered mental status
- Obtundation
- Coma
- Status epilepticus
Epidemiology
- Hyponatremia is the most common body fluid disorder and electrolyte imbalance encountered in clinical practice
- Accounts for 15-30% of emergency admissions in hospital and associated with increased morbidity, mortality and length of hospital stay in patients presenting with a range of conditions
- Increases risk of falls and osteoporosis and in severe cases it can be associated with mental state changes, including risk of coma and seizures
Pathophysiology
- Osmolality (total concentration of solutes in water) of plasma plays a role in the pathophysiology of hyponatremia
- Arginine vasopressin [antidiuretic hormone (ADH)] system and thirst strict regulation help maintain plasma osmolality
- Increase in plasma osmolality leads to ADH secretion and water retention which decreases serum osmolality
- Decrease in plasma osmolality decreases ADH that will result in diuresis of free water and a return to homeostasis
- Hyponatremia is a disorder of water imbalance where there is a relative excess of body water compared to total body sodium and potassium content due to impaired renal water excretion
- Usually associated with disturbance in the ADH that governs water balance
