Abstract
Introduction
C-reactive protein (CRP) and procalcitonin (PCT) are widely used as markers of inflammation and infection in general population and in chronic hemodialysis (HD) as well. However, in dialysis (D) patients, serum CRP and PCT levels may be elevated even in the absence of inflammatory or infectious disease and diagnostic process is a challenge in such cases. We studied HD patients' laboratory profile concerning CRP and PCT.
Subjects and Methods
We studied 25 stable HD patients, M/F=22/3, aged 68(44-89) years, dialyzed thrice weekly for 55(6-274) months with a dialysate flow rate of 700 ml/min, with a residual daily diuresis less than 200 ml, Kt/V values of 1,44±0,3 and no signs of infection. Patients were classified in two groups. Group A included 10 patients on pre-dilution online hemodiafiltration (HDF). Group B consisted of 15 patients on conventional HD with low-flux polysulfone membrane. Twenty healthy subjects formed a control group C. Serum CRP and PCT levels were measured in duplicate in A and B groups before and at the end of mid-week dialysis sessions and also in C group.
Results
Pre-D serum CRP values in the total of patients were higher than those in healthy controls (10,89±19,29 vs 2,54±1,28 mg/L-p=0,004). Compared with group C, pre-D CRP values were higher only in B group (15,98±24,54 mg/L-p=0,001) but not in A group (4,09±3,33 mg/L-p=NS). There was a significant difference in pre-D serum CRP values between A and B groups (p=0,028). At the end of D session serum CRP values showed a tendency to increase in both groups A (5,16±4,81 mg/L) and B (17,00±27,00 mg/L) but differences were not significant.
Pre-D serum PCT values in the total of patients were higher than those in healthy controls (0,82±0,9 vs 0,29±0,55 ng/ml-p<0,001). Compared with group C, pre-D PCT values were higher in both A group (0,52±0,15 ng/ml-p<0,001) and B group (1,01±1,13 ng/ml-p=0,006). There was no significant difference in pre-D serum PCT values between A and B groups (p=0,261). At the end of D session serum PCT values decreased in A group (0,32±0,11 ng/ml-p<0,001) and increased in B group (1,12±1,21 ng/ml-p=0,014).
Conclusions
In patients on both conventional low-flux HD and online HDF pre-D serum CRP and PCT levels were higher than those in healthy subjects. Dialysis modality and membrane flux did not affect post-D serum CRP values, but post-PCT values decreased in online HDF. PCT usefulness might be limited in dialysis with high-flux membranes. Cut-off values have to be established for both markers to eliminate confusion in diagnosis of inflammatory and infectious diseases in hemodialyzed patients.
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