Salivary Stress Biomarkers (Chromogranin A and Secretory IgA): Associations with Anxiety and Depressive Symptoms in Healthcare Professionals

Background/Objectives: Shift-working healthcare professionals are exposed to high psychophysiological demands associated with occupational stress, anxiety, and depressive symptoms. Salivary chromogranin A (sCgA) and secretory immunoglobulin A (sIgA) are non-invasive biomarkers reflecting sympathetic nervous system activation and mucosal immune function, respectively, and are increasingly used to assess biological stress responses. This study examined changes in these biomarkers and their associations with anxiety and depression. Methods: This cross-sectional comparative observational study was conducted among healthcare professionals working 12-h shifts (n = 95) and non-shift-working controls (n = 95) and included a within-shift pre-post assessment, with saliva samples collected before and after the work shift. Salivary biomarkers were determined using ELISA methods. Anxiety and depression were assessed using the State–Trait Anxiety Inventory and the Zung Self-Rating Depression Scale. Data were analyzed with t-tests, correlation, and multiple linear regression. Statistical analyses included between- and within-group comparisons, correlation analyses, and multiple linear regression models to examine independent associations between salivary biomarkers and psychological outcomes. Results: After a 12-h shift, healthcare professionals showed increased sCgA (3.82 ± 0.95 vs. 4.68 ± 1.02 ng/mL; p < 0.001) and decreased sIgA (165.3 ± 32.4 vs. 142.6 ± 29.8 mg/dL; p < 0.001). Psychological scores were higher in healthcare professionals than in controls (p < 0.001). Salivary sCgA correlated positively with anxiety and depression (r = 0.41 to 0.45), while sIgA correlated negatively (r = −0.29 to −0.36). Regression analysis confirmed occupational group (healthcare professionals vs. controls) as the strongest predictor, with independent contributions of sCgA and sIgA to psychological scores. Conclusions: A 12-h work shift in healthcare professionals leads to increased salivary chromogranin A, indicating sympathetic activation, and decreased secretory IgA, reflecting reduced mucosal immune activity. The combined assessment of sCgA and sIgA provides a sensitive and non-invasive approach for monitoring occupational stress and identifying early risks of anxiety and depressive symptoms among shift-working healthcare professionals.