Comparison of 3 automated assays for C-reactive protein in end-stage renal disease: clinical and epidemiological implications.

Chronic inflammation has been repeatedly reported in individuals undergoing hemodialysis. C-reactive protein (CRP) is considered a marker of chronic inflammation, as well as a mediator of the atherosclerotic process. Clinical and epidemiologic studies are based on plasma values obtained with the use of various automated methods. Our aim was to test 3 commercially available methods and compare the values obtained with the use of these tests in a population of individuals undergoing hemodialysis. We compared the following methods: immunoturbidimetry (AU2700 biochemistry analyzer; Olympus, Rungis, France) laser nephelometry (Behring Diagnostics, Marburg, Germany), and nephelometry (Beckman Instruments, Fullerton, Calif. The 3 methods were used in 3 different centers: Montpellier, France; and Pisa and Turin, Italy, respectively. We prepared samples for the estimation of imprecision values (ie, coefficient of variation [CV]) from the plasma of normal patients by adding purified C-reactive protein at concentrations ranging from 2.6 to 180 mg/L for intraassay variation and concentrations of 0, 1, 2, 3, 5, 10, 20, 50, 100, 150, and 180 mg/L for interassay variation. Intraassay imprecision was determined with the use of 10 replicate analyses on the same sample of the same day. We assessed interassay imprecision using the same sample, divided into aliquots and measured on 5 consecutive days. Agreement between methods was assessed on predialysis serum samples collected from patients with stable chronic kidney disease who were undergoing long-term hemodialysis at the 3 different centers (Montpellier,192; Pisa, 56; Turin,98). Serum was separated from the red cells and stored in 3 aliquots at -70 degrees C until it could be analyzed. Samples were thawed only once, circulated among the 3 centers, and each tested with all 3 of the methods. The Beckman method yielded the most precise results, with intraassay CVs ranging from 1 to 2 and interassay CVs ranging from 1 to 4. The Behring method was the least precise, with intraassay and interassay CVs ranging from 12 to 15 and 7 to 16, respectively. The results of the Olympus method fell between those of the other 2 methods. Agreement between the results of the Olympus and Behring methods was satisfactorily. The Beckman and Olympus methods yielded, on average, similar results over the entire range of CRP values. We detected significant disagreement between the Beckman method and the other 2 methods, obtaining results 10 to 100 times lower with the Beckman method. This became evident in terms of kappa-statistics. Our findings emphasize the need for careful assessment of the methods used to detect CRP in serum samples. Failure to do so may ultimately have a negative impact on the real relevance of CRP as a marker and on the role of chronic implication particularly in epidemiologic studies.

Do circulating cytokines really matter in sepsis?

Sepsis remains the major cause of mortality worldwide, claiming millions of lives each year. The past decade has seen major advances in the understanding of the biological mechanisms involved in this complex process. Unfortunately, no definitive therapy yet exists that can successfully treat sepsis and its complications. In this review, we will address the significance of circulating cytokines in the pathophysiology of sepsis and its relevance to new approaches in extracorporeal therapies.

A pilot study of coupled plasma filtration with adsorption in septic shock.

OBJECTIVE: To test the hypothesis that nonselective plasma adsorption by a hydrophobic resin (coupled plasmafiltration and adsorption) could improve hemodynamics and restore leukocyte responsiveness in patients with septic shock. DESIGN: Prospective, pilot, crossover clinical trial. SETTING: General intensive care unit in a teaching hospital. SUBJECTS: Ten patients with hyperdynamic septic shock. INTERVENTIONS: Patients were randomly allocated to 10 hrs of either coupled plasma filtration adsorption plus hemodialysis (treatment A) or continuous venovenous hemodiafiltration (treatment B) in random order. We measured the change in mean arterial pressure, norepinephrine requirements, and leukocyte tumor necrosis factor-alpha (TNF-alpha) production (both spontaneous and lipopolysaccharide-stimulated) after 10 hrs of each treatment. We also tested TNF-alpha production from normal human adherent monocytes incubated with patients' plasma obtained before and after the resin, both with or without incubation with an anti-interleukin-10 monoclonal antibody. RESULTS: Mean arterial pressure increased after 10 hr by 11.8 mm Hg with treatment A and by 5.5 mm Hg with treatment B (p =.001). There was an average decrease of norepinephrine requirement of 0.08 microg/kg/min with treatment A and 0.0049 microg/kg/min with treatment B (p =.003). All patients but one survived. Spontaneous and lipopolysaccharide-induced TNF-alpha production from patients' whole blood increased over time with treatment A. This increase was more marked in blood drawn after the device (plasmafiltrate-sorbent plus hemodialyzer) (p =.009). Preresin plasma suppressed lipopolysaccharide-stimulated production of TNF-alpha by 1 x 10(6)cultured adherent monocytes from healthy donors. This suppressive effect was significantly reduced after passage of plasma through the resin (p =.019) and after incubation with anti-interleukin-10 monoclonal antibodies (p =.028). CONCLUSIONS: In patients with septic shock, coupled plasmafiltration-adsorption combined with hemodialysis was associated with improved hemodynamics compared with continuous venovenous hemodiafiltration. This result might be related to its ability to restore leukocyte responsiveness to lipopolysaccharide. These findings suggest a potential role for blood purification in the treatment of septic shock.