Hyponatremia (HPN) is a potentially lethal electrolytic disturbance. Certain medical treatments are integrated in the etiology of that sodium disorder. We retrospectively studied the rate of HPN in patients examined in the emergency room (ER) of Alexandra Hospital receiving a selective serotonin reuptake inhibitor (SSRI).

17,410 patients, 55.54% women and 44.46% men were examined in the ER over a one year period. 281 patients (1,61% of total) presented with HPN, 162 were women (57.6%) and 121 (42.3%) men. Plasma Sodium values ≤ 133mEq/l defined HPN. 13 of the 281 patients with HPN (4.6%) with no renal, heart or hepatic impairment were on an SSRI regimen.

11 of 162 women (6.8%) presented with HPN were receiving concurrently SSRI and either thiazide diuretic (3 ) or furosemide (2 ). 2 of 121 men (1.65%) were on SSRI regimen and furosemide. SSRI dosage was in all cases within suggested therapeutic limits. Table 1 demonstrates mean values and standard deviation of all the parameters examined.

SSRI therapy presents a potential cause for HPN principally in women older than 65 years old with increasing risk when diuretic is used concomitantly. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) and expression conversion of aquaporin-2 receptors of the collecting ducts are two possible pathophysiologic mechanisms of HPN occurrence.