Hyponatremia

Hyponatremia is serum sodium below 135 mmol/L, the most common electrolyte abnormality. Classification by volume status: hypovolemic (GI/renal loss), euvolemic (SIADH, adrenal insufficiency, hypothyroidism), hypervolemic (heart failure, cirrhosis, nephrotic syndrome). Clinical: headache, nausea/vomiting, confusion, seizures; severe causes cerebral edema/herniation. Treatment: identify/underlying cause; fluid restriction for SIADH; isotonic saline for hypovolemia; hypertonic saline for severe symptomatic; correct slowly (avoid central pontine myelinolysis).

Common Symptoms

Headache; nausea; confusion; lethargy; seizures; cerebral edema; often asymptomatic if mild/chronic

Causes and Pathogenesis

Impaired water excretion relative to sodium causes hypotonicity; brain cells swell, causing neurologic symptoms.

Treatment

Treat underlying cause; fluid restriction (SIADH); isotonic saline (hypovolemic); 3% saline for severe symptomatic; vasopressin antagonists; correct slowly

Preventive Measures

Avoid excess free water; monitor in SIADH/heart failure/cirrhosis; careful diuretic use.

Department to Visit

It is recommended to visit the Internal Medicine department; an appointment can be booked on this platform before the visit.

Warm reminder: The above information is for health science reference only and cannot replace professional medical diagnosis. If you have related symptoms, please seek medical attention at a regular hospital promptly.