What are the key clinical features to assess in a patient with suspected hyponatremia?

When assessing a patient with suspected hyponatremia, key clinical features to evaluate include the severity and onset of symptoms, neurological status, volume status, and potential underlying causes. Neurological assessment is critical because hyponatremia can cause symptoms ranging from mild confusion, headache, nausea, and vomiting to severe manifestations such as seizures, reduced consciousness, and coma, reflecting cerebral oedema risk NICE NG29 Hoorn & Zietse 2008. Volume status assessment helps differentiate between hypovolemic, euvolemic, and hypervolemic hyponatremia, guiding management; signs include orthostatic hypotension, tachycardia, peripheral oedema, ascites, and jugular venous pressure NICE NG29 Martín-Llahí et al. 2006. History and examination should focus on recent fluid losses (vomiting, diarrhoea), medication use (diuretics, antidepressants), comorbidities (heart failure, liver cirrhosis, renal disease), and symptoms suggestive of endocrine disorders (e.g., hypothyroidism, adrenal insufficiency) NICE NG29 Sumi et al. 2025. Severity and acuity of hyponatremia influence clinical presentation; acute drops in sodium often cause more pronounced neurological symptoms than chronic hyponatremia NICE NG29 Hoorn & Zietse 2008. Additional features such as signs of infection or systemic illness should also be assessed to identify precipitating factors NICE NG29. This integrated clinical evaluation is essential to guide appropriate investigations and treatment decisions in hyponatremia management.