C reactive protein in patients with chronic renal diseases

Base-line serum levels of plasma C-reactive protein (CAP} are predictive of future myocardial infarction and sudden cardiac det in apparently healthy subjects, suggesting the hypothesis that chronic inflammation might be impo rtant in. the pathogenesis of atherothrombosis. CRP production is mediated by several inflammatory mediators: interleukin 6 (IL-6) is currently felt t o be the major cytokine influencing the. acute phase response: CRP and othe r acute phase proteins are elevated in dialysis patients and cardiovascular diseases represent the single largest cause of mortality in chronic renal failure patients. Little information is available, however regarding CRP an d IL-6 plasma lever in pre-dialysis renal failure. Plasma CRP was determine d by a modification of the laser nephelometry technique; IL-6 by immunoassa y (RD hysteria); and fibrinogen, serum albumin, cholesterol, triglycerides, hematocrit, white blood cell count, erythrocytic sedimentation rate (ESR) and urinary protein levels by standard laboratory techniques. Results were obtained in 102 chronic pre-dialysis patients whose mean age was 53 +/- 5.8 years with a mean creatinine clearance (C-Cr) of 52 +/- 37 mL/min). CRP wa s greater than 5 mg/L in 25% of the global population. CRP and IL-6 were 4. 0 +/- 4.6 mg/L and 5.8 +/- 5.6 pg/mL, respectively and were not significant ly correlated (r = 0.11, p = n.s.). CRP and IL-6 were however related with renal function (CRP versus C-Cr r = -0.40 p < 0.001; IL-6 versus C-Cr r = - 0.45; p < 0.001). When patients were divided in two groups according to ren al function, CRP resulted 7.4 +/- 6.3 mg/L in the group of patients with a Car lower than 20 mL/min (n = 32) and 2.76 +/- 4.35 in the group of patient s with a C-Cr higher than 20 mL/min (n = 70) (p < 0.0001). CRP and IL-6 wer e positively related with ESR (r = 0.32 and 0.46 respectively). Serum album in levels were not significantly different in the two groups of patients (3 .2 +/- 0.4 versus 3.0 +/- 0.5 g/dL). CRP and serum albumin were not signifi cantly related (r = 0.17). CRP and IL-6 correlated positively with ESR (r = 0.32 and 0.46 respectively). In pre-dialysis patients we have demonstrated an increase in both CRP and IL-6 that occurs as renal function decreases. These data provided evidence of the activation - even in the predialysis ph ase of renal failure - of mechanisms known to contribute to the enhanced ca rdiovascular morbidity and mortality of the uremic syndrome.