Abstract: Objective To investigate the changes of plasma procalcitonin and C-reactive protein (CRP) in patients with Pneumocystis pneumonia(PCP) following renal transplantation and to study the value of differential diagnosis of Pneumocystis and bacterial pneumonia. Methods Fifty-five patients with PCP after renal transplantation in the hospital were examined for procalcitonin and CRP by prospective clinical observation. The patients were divided into two groups according to the diagnosis methods, and the patients with PCP after transplantation were divided into two groups: group of definitive diagnosis (group A) and group of clinically suspected diagnosis(group B). The patients of group B were described and compared with the data collected by appropriate statistical methods. Results The serum procalcitonin concentration in 55 patients with PCP remained unchanged. The CRP concentration in 47 of the 55(87.5%) patients showed a slight increase. The serum levels of procalcitonin and CRP in group B were found to be slightly higher than those in group A but no significant difference was noted (P>0 05). Conclusion Procalcitonin and CRP concentrations remains unchanged significantly in PCP patients after renal transplantation, both can not be used for differential diagnosis of Pneumocystis or bacteria pneumonia.

Key words: Kidney transplant, Pneumocystis infection, Procalcitonin, CRP