Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT Part 21-02: Hyponatremia + Key Features Download Section PDF Listen +++ ++ A diagnosis of exclusion Euvolemic hyponatremia Other causes of hyponatremia should be ruled out, including Low effective circulating volume Decreased solute intake Cortisol deficiency Severe hypothyroidism See Hyponatremia + Clinical Findings Download Section PDF Listen +++ ++ Characterized by Hyponatremia Decreased plasma osmolality (< 280 mOsm/kg) Euvolemia Absence of heart, kidney, or liver disease Normal thyroid and adrenal function Urine sodium usually > 20 mEq/L + Diagnosis Download Section PDF Listen +++ ++ Clinical Patients with SIADH may have low blood urea nitrogen (BUN) (< 10 mg/dL [3.6 mmol/L]) and hypouricemia (< 4 mg/dL [238 mcmol/L]), which are not only dilutional but result from increased urea and uric acid clearances in response to the volume-expanded state + Treatment Download Section PDF Listen +++ ++ See Hyponatremia