A smoker presented with altered sensorium. His blood osmolality was found to be 240 and urine osmolality 340. His Na+ is 122 meq/L. The diagnosis is

(B) SIADH # Psychogenic polydipsia and beer potomania--Marked excess free water intake (generally >10 L/d) may produce hyponatremia.> Euvolemia is maintained through the renal excretion of sodium.> Urine sodium is therefore generally elevated (> 20 mEq/L), but unlike SIADH, levels of ADH are suppressed.> Urine osmolality is appropriately low (< 300 mosm/kg) as the increased free water is excreted.> Hyponatremia from bursts of ADH occurs in manic-depressive patients with excess free water intake.> Psychogenic polydipsia is observed in patients with psychological problems, and these patients frequently take drugs interfering with water excretion.> Similarly, excessive intake of beer, which contains very small amounts of sodium (< 5 mEq/L), can cause severe hyponatremia in cirrhotic patients, who have elevated ADH and often a decreased GFR.