Clinical significance of C-reactive protein in patients on hemodialysis: a longitudinal study

The levels of C-reactive protein (CRP) have been related to hypoalbuminemia and the necessity of erythropoietin in patients on maintenance hemodialysis. However, in several studies, the patients' clinical situation is not taken into account. The aim of the present work was to analyze the relationship between CRP and serum albumin and hemoglobin and the erythropoietin resistance index (ERI) in a population of patients on chronic hemodialysis classified according to their clinical situation.

In a cohort of 53 patients followed for 12 months, we analyzed the CRP level and its association with albumin and hemoglobin levels and the ERI (ratio of total weekly erythropoietin dose in units/weight to hemoglobin concentration in g/dl) at the start of the study and at 6 and 12 months thereafter. The patients were divided into three groups based on the presence of inflammatory/infectious disorders during the 4 weeks prior to CRP determination (group A) or the use of a jugular catheter (group B) or an arteriovenous fistula (group C) as vascular access for hemodialysis.

At baseline, the CRP levels (47.1 mg/l in group A, 30.7 mg/l in group B, and 9.4 mg/l in group C) and the ERI (23.9 in group A, 24.6 in group B, and 10.7 in group C) were higher in groups A and B than in group C (p < 0.001 for both parameters). Serum albumin (3.9 g/dl in group A, 4.1 g/dl in group B, and 4.4 g/dl in group C) and hemoglobin (10.4 g/dl in group A, 11.3 g/dl in group B, and 12 g/dl in group C) were lower in groups A and B than in group C (p < 0.05 for serum albumin and p < 0.01 for hemoglobin). In all patients, the baseline CRP level correlated with the albumin level (r = -0.3853, p < 0.01), with the hemoglobin level (r = -0.2950, p < 0.05), and with the ERI (r = 0.4378, p < 0.01). However, if we only considered the group C patients, there was no correlation between baseline CRP and albumin, hemoglobin, and ERI. Similar results were observed at 6 and 12 months.

The CRP, albumin, and hemoglobin levels and the ERI mostly depend on the existence of ongoing inflammatory/infectious disorders and the use of a catheter as vascular access. In the absence of these clinical conditions, we could not correlate the CRP level with the other parameters. The relationship between CRP, albumin, and anemia may be an epiphenomenon.