Importance of Prolidase Enzyme Activity and Serum Cytokeratin 18 Levels for Differential Diagnosis between Asymptomatic Hepatitis B Carriers and HBeAg Negative Chronic Hepatitis B Patients

Background: In this study, it was aimed to evaluate the relationship between the severity of necroinflammation in the liver and the stage of fibrosis and the serum levels of Serum Prolidase Activity (SPA) and Cytokeratin (CK)-18 in patients with active Chronic Hepatitis B (CHB) and asymptomatic Hepatitis B Virus (HBV) carriers. Methods: Biochemical analyses, serological parameters associated with HBV and serum prolidase activity and CK-18 levels were measured in asymptomatic HBV carriers (n=65), active CHB patients (n=60) and healthy controls (n=27). Liver biopsies were performed on asymptomatic HBV carriers and active CHB patients. Findings: SPA level was significantly higher in active CHB patients (819.92 ± 123.74 IU/L) compared to asymptomatic HBV carriers (732.99 ± 124.70 IU/L) and was higher in asymptomatic HBV carriers compared to healthy controls (529.4 ± 74.73 IU/L) (p=0.001). The diagnostic cut-off value of SPA level was found 751.15 U/L. When this cut-off value was taken to differentiate HBe-Ag negative CHB in asymptomatic HBV carriers, sensitivity and specificity of efficacy were 72% and 63% respectively (c-statistics: 0.707). A strong positive correlation was observed between serum prolidase level and the severity of fibrosis in asymptomatic HBV carriers (r=0.603, p=0.000). A positive correlation was determined between SPA level and Histological Activity Index (HAI) scores in patients with active CHB and asymptomatic HBV carriers. The serum CK-18 levels were significantly lower in the healthy control group when compared to the asymptomatic HBV carriers and active CHB patients (p=0.001). Conclusion: Prolidase enzyme may be beneficial in differentiating asymptomatic HBV carriers from HBeAg-negative CHB patients when used in combination with ALT and HBV-DNA levels.