To investigate the changes of VCS parameters of blood white cells in the process of anti-tuberculosis drugs treatment and its clinical value during monitoring granulocyte decrease induced by anti-tuberculosis drug.

Peripheral blood samples collected from 500 healthy controls and 633 patients with tuberculosis were detected for neutrophils absolute value (ANC), neutrophil (NE%), neutrophil average volume (MNV), neutrophil average conductivity (MNC), neutrophils average values of light scattering (MNS) and its corresponding standard deviation (SD) by the Coulter LH750 hematology analyzer. The neutrophil VCS parameters were detected and VCS variation (△VCS) before and after therapy were calculated, respectively. Patients were divided into control group (489 cases, with normal blood routine indexes) and neutropenia group (65 cases, with ANC < 2.0 × 10⁹/L) according to the clinical symptoms and laboratory examination, data analysis between groups were compared, respectively.

MNV of improved period and MNV-SD of patients in the control group were increased significantly compared with those before treatment (t = 2.207, P = 0.030; t = 2.030, P = 2.030), but MNS decreased significantly (t = 2.104, P = 2.104). Compared with the indexes before treatment, MNV of one week before granulocyte decline, MNV-SD and MNS changed significantly (t = 27.953, 27.953, 27.953; all P < 0.001), but the ANC and NE% were with no significant change (t = 2.032, P = 0.051; t = 1.977, P = 0.052). When ANC dropped to 2.0 × 10⁹/L, △MNV was negatively correlated with △ANC (r = 0.868, P < 0.001), but △MNS was positively correlated with △ANC (r = 0.847, P = 0.000). MNV of one week before granulocyte decline, MNV-SD and MNS area under the ROC curve were 0.867, 0.778 and 0.867, respectively, significantly higher than the ANC (AUC = 0.633) and NE% (AUC = 0.589), and as the MNV Cut-off ≥ 150.05, the sensitivity and specificity were 82.3% and 82.3%, respectively, this diagnosis method was better than other indicators. When ANC + NE% + MNV + MNV-SD + MNS was taken as joint diagnosis, its sensitivity and speciality rate were 88.5% and 88.5%, respectively.

Anti-tuberculosis drugs could cause higher MNV and MNV-SD, but decreased MNS; when drug induced granulocyte decrease occure, changes of MNV, MNV-SD and MNS were more significant. The joint diagnosis with the ANC and NE% could make higher sensitivity and specificity before granulocyte decline.