Point of care cardiac ultrasound in the management of hyponatremia: an enhancement to physical examination

Accurate assessment of fluid status is vital to appropriate management of hyponatremia. However, conventional parameters such as physical examination, vital signs, and laboratory markers such as natriuretic peptides suffer from limitations in this regard. Point of care ultrasonography (POCUS) is a noninvasive bedside diagnostic tool that is emerging as an adjunct to physical examination in internal medicine and subspecialties including nephrology. In this manuscript, we describe a complex case of hyponatremia, where stroke volume assessment using Doppler echocardiography has helped to objectively assess fluid status and guided therapy. A 73-year-old woman was seen for worsening serum sodium. Her urine sodium was high and there was no hypotension suggestive of euvolemia. However, POCUS demonstrated low stroke volume in the presence of normal left ventricular ejection fraction, indicative of hypovolemia. She was treated with intravenous fluids based on these findings and response was evident by normalization of the stroke volume. Clinicians should adopt a multi-parametric approach integrating all the pieces of hemodynamic puzzle when evaluating complex fluid and electrolyte disorders.