Admission Hyponatremia and its Clinical Correlates in Male Psychiatric Inpatients: A Retrospective Study From Turkey

Objective Hyponatremia is a common electrolyte disturbance in psychiatric patients related to psychogenic polydipsia, psychotropic medications, and medical comorbidities. Data on the prevalence of admission hyponatremia and its independent clinical correlates in psychiatric inpatients remain limited. Method This retrospective study included 322 consecutive male psychiatric inpatients hospitalized between June and December 2022. Hyponatremia was defined as serum sodium <135 mEq/L within 24 h of admission. Sociodemographic, clinical, and laboratory data were extracted from electronic medical records. Age and disease duration were entered into a Firth penalized logistic regression model. Sensitivity analyses used alternative sodium cut-offs (<134 and <136 mEq/L), glucose-corrected sodium, and continuous sodium. Results Hyponatremia was identified in 15 patients (4.7%, 95% CI 2.8-7.5%). Older age, longer disease duration, and a greater number of psychiatric hospitalizations were associated with hyponatremia in univariable analyses. After adjustment for age, disease duration remained associated with hyponatremia (OR = 1.07 per year, 95% CI = 1.02-1.14, P = .006), with similar estimates across alternative sodium cut-off values, but was not associated with continuous sodium. Diabetes mellitus was also associated with hyponatremia univariably, though this should be interpreted with caution given the small number of affected patients and its attenuation after glucose correction. Conclusions Admission hyponatremia was identified in 4.7% of male psychiatric inpatients. Disease duration was associated with hyponatremia after adjustment for age, although its contribution cannot be fully separated from that of age. These findings support careful evaluation of abnormal admission serum sodium values. Prospective multicenter studies are needed to confirm these findings and clarify underlying mechanisms.