Diagnostic criteria for syndrome of inappropriate antidiuretic hormone secretion

The Diagnostic Criteria for Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH) is a clinical tool designed to aid in the diagnosis of SIADH, a condition characterized by excessive release of antidiuretic hormone from the posterior pituitary gland or other sources. The criteria are primarily used to identify patients with hyponatremia, a common electrolyte disorder, who may have SIADH as the underlying cause. The diagnostic criteria consist of essential and supplemental components. The essential criteria include effective serum osmolality less than 275 mOsm/kg, urine osmolality greater than 100 mOsm/kg, absence of clinical evidence of hypovolemia or hypervolemia, urine sodium concentration greater than 30 mmol/L with normal dietary salt and water intake, absence of adrenal, thyroid, pituitary or renal insufficiency, and no recent use of diuretic agents. The supplemental criteria, which provide additional diagnostic support, include serum uric acid less than 0.24 mmol/L, serum urea less than 3.6 mmol/L, failure to correct hyponatremia after 0.9% saline infusion, fractional sodium excretion greater than 0.5%, fractional urea excretion greater than 55%, fractional uric acid excretion greater than 12%, and correction of hyponatremia through fluid restriction. The Diagnostic Criteria for SIADH is a comprehensive tool that incorporates a wide range of clinical and laboratory parameters, providing a robust framework for the diagnosis of this complex disorder.

Reference

Goce Spasovski, Raymond Vanholder, Bruno Allolio et al. Clinical practice guideline on diagnosis and treatment of hyponatraemia. Eur J Endocrinol. 2014 Feb 25;170(3):G1-47.