AVP and Hyponatremia: There are two mechanisms postulated for cytokine-induced hyponatremia; one is direct stimulation of the hypothalamohypophyseal and, subsequently, the nonosmotic release of antidiuretic hormone (ADH) [5] or ventilation-perfusion mismatch induced by alveolar cell injury secondary to cytokines release, which can cause SIADH as a result of inadequate left atrium filling secondary to hypoxic pulmonary vasoconstriction [5,7].