Background: Bacterial infections are associated with a high morbidity and mortality rate in patients with acute and chronic renal failure. Because C-reactive-protein (CRP) is elevated in many patients with renal failure, even in the absence of infection, procalcitonin (PCT) might be useful for the detection of systemic bacterial infections. This cross-sectional observation study measured PCT and CRP in several groups of patients with various types, degrees and treatments of kidney diseases, including patients with sepsis treated with renal replacement therapy.
Patients and methods: We determined PCT and CRP in 85 renal patients with different stages and treatments of renal insufficiency: chronic renal failure (CRF) n=23, patients undergoing continuous ambulatory peritoneal dialysis (CAPD) n=20, patients undergoing hemodialysis therapy (HD) n=42 and in a group of 40 patients with septic conditions, including 20 patients with acute renal failure (ARF). The infectious status of the patients was monitored.
Results: PCT in serum (reference value in healthy controls < 1 microg/l) was within the normal range in patients with CRF and in patients on both short-term HD (< 1 year) and long-term HD (> 1 year) (median of 0.25 microg/l and 0.61 microg/l). However, PCT was elevated in patients on CAPD (median of 1.18 microg/l). In patients with sepsis, PCT was massively elevated in both the presence and absence of ARF. In contrast, CRP (reference value < 5 mg/l) was markedly increased in patients undergoing short- and long-term HD (medians of 14.5 and 51.1 mg/l) but not in patients on CAPD. In patients with CRF and systemic bacterial infections, both PCT and CRP were markedly elevated (median PCT 63 microg/l, CRP 130 mg/l) but, in contrast to PCT, CRP values overlapped in infected and non-infected patients. There was no relevant decrease in plasma concentrations of PCT by hemofiltration or hemodialysis in patients with sepsis.
Conclusion: With the exception of CAPD patients, PCT levels were not significantly affected by renal diseases or treatments but were markedly elevated in the presence of infections. Thus PCT is a valuable marker for early diagnosis of systemic bacterial infections in patients with CRF or patients undergoing HD. In contrast, CRP is elevated in several groups with renal diseases and has low specificity for the diagnosis of bacterial infections.