Approach to hyponatremia: the value of fractional excretion of uric acid and phosphate

This case report highlights the central role of the laboratory in the study of hyponatremia. The joint evaluation of biomarkers such as uric acid, fractional excretion of uric acid, phosphorus, and fractional excretion of phosphate allows for a more accurate differential diagnosis between SIADH and CSWS, overcoming the limitations of the volume approach and thus minimizing the risks associated with invasive or inconclusive therapeutic tests and delays in the implementation of therapeutic measures.