1Faculty of Medicine, Vilnius University, Vilnius, Lithuania
Hyponatremia defined as a serum sodium concentration below 135 mmol/l, is the most common water and electrolyte balance disorder, that often poses diagnostic and management challenges. Hyponatremia is classified based on serum sodium concentration, time of presence, clinical symptoms, osmolality and volemic status. The causes of hyponatremia are various, including low sodium intake, syndrome of inappropriate antidiuretic hormone secretion, use of diuretics or other drugs, nephrotic syndrome, polydipsia, vomiting and diarrhea, adrenal insufficiency, hypovolemia, heart failure and cirrhosis. Precise diagnosis of hyponatremia determines most effective approach of treatment. Clinical symptoms of hyponatremia depend on the duration and severity of hyponatremia: from asymptomatic cases or mild, non-specific symptoms (nausea, vomiting, headache and confusion) to severe symptoms (altered mental status, delirium, seizures and coma). The classification, etiology and manifestation of the disease shows that this condition is very heterogeneous. Although hyponatremia is associated with worse outcomes and longer hospitalization, hyponatremia is often misdiagnosed and mistreated. The diagnosis of hyponatremia should be based on symptoms, its duration, extensive anamnesis and physical examination. The treatment of severe symptomatic hyponatremia is independent on the cause. Severe symptomatic hyponatremia should be treated with quick intravenous hypertonic sodium chloride infusion. The treatment of mild and moderate hyponatremia should be based on the etiology. During correction of hyponatremia, avoid rapid overcorrection of serum sodium concentration, which can result in osmotic demyelination syndrome.
Keywords: hyponatremia, severe hyponatremia, sodium, electrolytes, homeostasis.