Objective
To detect the serum expression of cathepsin B and cystatin C and the ratio of cathepsin B to cystatin C in patients with pelvic inflammatory disease (PID) and speculate whether those are helpful indicators for the diagnosis of PID. Design: A random consecutive study. Setting: University hospital. Patient(s): Forty-four women who were diagnosed with PID. Intervention(s): Collected blood specimens of patients before and after they received treatment. Main outcome measure(s): ELISA analysis was used to measure the serum levels of cathepsin B and cystatin C. Result(s): A significantly increased expression of cathepsin B but decreased expression of cystatin C and significant correlations between neutrophils and cathepsin B, as well as between C-reactive protein (CRP) and cathepsin B, were found in patients with PID. Consistently, the ratio of cathepsin B to cystatin C correlated significantly with neutrophils and with CRP in patients with PID.