Evaluation of Serum Zonulin Levels and Their Association with the Clinical Course of Brucellosis

Background: This study aimed to determine whether serum zonulin levels could serve as a potential diagnostic biomarker for distinguishing acute, subacute, and chronic stages of brucellosis and to evaluate their relationship with routine biochemical and hematological parameters. Methods: A total of 153 patients diagnosed with brucellosis and 51 healthy controls, were included in the study. Based on clinical findings, symptom duration, and serological test results, patients were classified as acute, subacute, or chronic. Serum zonulin concentrations were measured using a commercially available enzyme-linked immunosorbent assay ELISA kit (Human Zonulin ELISA Kit; BT LAB, Cat. No. E3704Hu, China). Results: Median zonulin levels were 24.57 (27.19) ng/mL in acute, 18.21 (14.00) ng/mL in subacute, 6.19 (2.87) ng/mL in chronic patients, and 5.81 (3.47) ng/mL in controls. Zonulin levels were significantly higher in the acute phase and decreased significantly with disease chronicity (p < 0.001). Conclusions: Serum zonulin levels were found to be higher in acute brucellosis compared to subacute and chronic cases. In brucellosis, more comprehensive research is needed to determine whether serum zonulin levels can be used as a diagnostic biomarker in the evaluation of different clinical forms.