RISK-FACTORS FOR THE DEVELOPMENT OF HYPONATREMIA IN PSYCHIATRIC-INPATIENTS

Background: When inpatients who are on psychiatry services develop hyp onatremia, medical consultation is usually required for evaluation and management, thus halting or delaying psychiatric treatment. Risk fact ors for the development of hyponatremia in this population have not be en studied. Methods: A case-control study of psychiatric inpatients in a tertiary care facility was performed. Sixty-four patients who had a serum sodium level of less than 130 mmol/L were identified; three con trol subjects were chosen from the inpatient psychiatry service for ea ch case. Risk factors investigated included medications, psychiatric d iagnoses, basic demographic variables, and medical comorbidities. Resu lts: Univariate and logistic regression analyses revealed that, in add ition to diuretic use (adjusted odds ratio, 8.2; 95% confidence interv als, 2.2 to 30.8), use of fluoxetine (adjusted odds ratio, 21.4; 95% c onfidence interval, 5.3 to 86.9), tricyclic antidepressants (adjusted odds ratio, 4.9; 95% confidence interval, 1.6 to 15.2), and calcium an tagonists (adjusted odds ratio, 4.0; 95% confidence interval, 1.1 to 1 4.2) were all associated with;the development of hyponatremia. Importa nt comorbidities included elevated creatinine levels, chronic obstruct ive pulmonary disease, hypertension, systolic blood pressure, and diab etes. Although age was significantly associated with hyponatremia in u nivariate analyses, it was not significant in multivariate analyses. C onclusions: Among psychiatric patients, hyponatremia is often associat ed with factors other than psychogenic polydipsia, including medicatio ns and medical. comorbidities: Although elderly psychiatric inpatients seem to develop hyponatremia more often than younger patients, once d rugs and comorbidities are taken into account, age does not appear to be a significant risk factor for hyponatremia in this population.