The Relationship Between Hemoglobin Levels and Depression Severity in Inpatients with Major Depressive Disorder

Objective: Major depressive disorder (MDD) is a psychiatric illness characterized by severe functional impairment arising from biopsychosocial interactions. Understanding biological indicators has gained increasing importance in the diagnosis and treatment of depression. This study aimed to investigate the relationship between hemoglobin (Hb) levels and depression severity in individuals diagnosed with MDD.Methods: This retrospective, cross-sectional study included 80 patients diagnosed with MDD according to DSM-5 criteria who were hospitalized in a psychiatry clinic between 2023 and 2025. Sociodemographic and clinical data were obtained retrospectively from patient files. Depression severity was assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS). The relationship between Hb level and depression severity was analyzed using Spearman correlation, and associations with depression severity were evaluated using multiple linear regression analysis.Results: The mean age of participants was 38.13 ± 12.76 years, and 66. 25% were female. The mean MADRS score was 30.24 ± 7.50, and the mean Hb level was 12.97 ± 2.12 g/dL. Correlation analysis revealed a significant negative relationship between Hb level and depression severity (ρ = –0.278, p = 0.013). Regression analysis suggested that Hb level may be associated with depression severity(B = –1.47, p = 0.002).Conclusion: The findings suggest that lower Hb levels may be associated with greater depression severity. These results may indicate a potential relationship between hematological parameters and the biological aspects of depression. However, due to the retrospective cross-sectional design of the study, no causal inferences can be made regarding the relationship between Hb levels and depressive symptoms. Future prospective studies with larger samples may help to further clarify the association between Hb levels, anemia-related parameters, and depression severity.