Υπονατριαιμία και ψυχοτρόπα: Αίτια και παθοφυσιολογικοί μηχανισμοί

Hyponatremia is a pathophysiologic process indicating water excess. It is the commonest electrolyte disturbance in hospitalized patients and among the commonest in elderly community dwellers. Many cases are mild and asymptomatic but the more serious ones are clinically important because they are related to increased morbidity and mortality. The usual mechanism of hyponatremia is inappropriate antidiuretic hormone secretion (SIADH) but SIADH-related diagnosis of hyponatremia in psychiatric patients may delay due to the fact that its symptoms may be identical to those of primary psychiatric disorders or sideeffects of many psychotropic drugs. Almost all psychotropic drugs may cause hyponatremia and clinicians should bear this fact in mind. Nevertheless, based both on clinical experience and research data, antidepressants (more specifically, venlafaxine and selective serotonin-reuptake inhibitors), antipsychotics (particularly the older ones) and, among antiepileptics used in psychiatry, carbamazepine and oxcarbazepine seem to be mostly implicated. Among drugs of abuse, ecstasy must raise increased clinical suspicion. Apart from SIADH, other causative mechanisms of hyponatremia may include decreased threshold of antidiuretic hormone secretion and the enhancement of its effects in renal collecting ducts. Psychogenic polydipsia, usually observed in patients with schizophrenia spectrum disorders, may also cause hyponatremia even though increased water intake per se is seldom of such an extent that could lead to hyponatremia if renal function is normal. In this paper, we briefly review the pathophysiologic mechanisms of hyponatremia and the psychotropic drugs that are more commonly implicated without mentioning epidemiological data or describing treatment methods. Our aim is to increase clinical vigilance of health care professionals and sensitize them to understand this side effect of many psychotropic drugs. Except for these drugs, we give data concerning drugs of abuse that may cause hyponatremia. [ABSTRACT FROM AUTHOR]