Background: Hyponatremia is a common electrolyte imbalance that clinicians face on a regular basis.
Summary: This review aims to discuss four current challenges that can arise when diagnosing and treating hyponatremia: low solute intake, heart failure, exercise-associated hyponatremia, and mild chronic hyponatremia. Low solute intake in a person who already has a urinary concentrating defect will lead to increased retention of free water. The free water retention will cause or worsen hyponatremia that is already present. Low solute intake is overlooked in patients with other disease processes that can cause hyponatremia, such as liver disease or heart failure. Heart failure and hyponatremia present their own set of challenges specifically with treatment as there are limited options. The newer class of aquaretics allows for the short-term treatment of hyponatremia. Exercise-associated hyponatremia is a phenomenon that has been described in ultra-endurance athletes. This happens when a person drinks a significant amount of water while exercising in the setting of antidiuretic hormone production from prolonged exercise. This acute drop in sodium must be treated with hypertonic saline. The term asymptomatic mild chronic hyponatremia is no longer valid. Mild chronic hyponatremia carries an increased risk of falls and fractures, specifically in the elderly populations.
Key message: In summary, hyponatremia is a multifaceted disease and presents many challenges for physicians treating it.
Keywords: Heart failure; Hyponatremia; Osmolality; Sodium; Vasopressin.