Clinical value of haptoglobin and soluble CD163 testing for the differential diagnosis of tuberculous and malignant pleural effusions

This study aims to evaluate the clinical value of haptoglobin (Hp) and sCD163 testing for the differential diagnosis of pleural effusion, and investigate the correlation of Hp and sCD163 with the inflammatory response of the body. Pleural effusion samples were collected from 78 patients (38 tuberculous pleural effusions [TPE] and 40 malignant pleural effusions [MPE]). The concentrations of Hp and sCD163 in the pleural effusion were measured by enzyme-linked immunosorbent assay (ELISA). The concentrations of Hp and sCD163 were significantly higher in the TPE group than in the MPE group (P < .05). The sensitivity and specificity of the Hp test for the differential diagnosis of TPE and MPE was 82.4% and 86.1%, respectively (P < .01), while the cut off value was 779.05 ug/mL. Furthermore, the sensitivity and specificity of the sCD163 test for the differential diagnosis of TPE and MPE was 76.3% and 85.0%, respectively (P < .01), while the cut off value was 16,401.11 ng/mL. Moreover, the sensitivity and specificity of the combination of Hp and sCD163 tests for diagnosing TPE was 90.0% and 87.5%, respectively. Hp and IL-1β, TNF-α, CRP and ESR were positively correlated in both the TPE group and MPE group (P < .05). Hp and sCD163 were positively correlated in the TPE group (r = 0.3735, P = .0209), but not in the MPE group (r = 0.22, P = .1684). However, there was no correlation between sCD163 and TNF-α, CRP and ESR in either the TPE group, or the MPE group (P > .05). Furthermore, sCD163 and IL-1β were weakly correlated in the TPE group (r = 0.49, P = .0018), but these had no correlation in the MPE group (r = 0.068, P = .6767). Hp and sCD163 can be used as biological markers for the differential diagnosis of pleural effusion in clinic, and the level of Hp in pleural effusion may reflect the intensity of inflammation in the body to some extent.