C-reactive protein and interleukin-6 levels are related to renal function in predialytic chronic renal failure.
BACKGROUND
Several studies have provided convincing evidence that in apparently healthy subjects elevated serum levels of plasma C-reactive protein (CRP) are associated with an increased risk of experiencing myocardial infarction and sudden cardiac death. It has been claimed that, in dialytic patients, the hepatic synthesis of this 'acute phase response' plasma protein is primarily induced by the macrophage-derived interleukin 6 (IL-6). Little information is available, however, regarding CRP and IL-6 plasma levels in pre-dialytic renal failure.


METHODS
Plasma CRP by a modification of the laser nephelometry technique, IL-6 and serum albumin were determined in 103 chronic pre-dialytic patients (mean age 50 +/- 6.3 years; creatinine clearance (Cr.cl.) 36.3 +/- 23.1 ml/min).


RESULTS
CRP was >5 mg/l (normal upper range) in 42% of the global population. CRP and IL-6 were significantly related (r = 0.35, p < 0.0004). CRP and IL-6 were related to renal function (CRP vs. Cr.cl., r = -0.56, p < 0.0001; IL-6 vs. Cr.cl., r = -0.55, p < 0.0001, Spearman correlation coefficient). When patients were divided in tertiles according to renal function, CRP median value resulted 7.9 mg/l (interquartile interval: 5-12) in the first tertile (Cr.cl. <18.5 ml/min), 4.0 mg/l (3-6) in the second tertile (Cr.cl. 18.5-45 ml/min) and 3.2 mg/l (2.7-4.0) in the last tertile (Cr.cl. >45 ml/min) (p < 0.0001). A negative correlation between CRP and S-albumin was also found (r = -0.52, p < 0.0001, Spearman correlation coefficient).


CONCLUSIONS
IL-6 and CRP were increased and were inversely related to creatinine clearance in our population of 103 chronic predialytic patients. The possibility of a decreased renal clearance of CRP and/or cytokines as a cause of an activated acute-phase response is discussed. A negative correlation between CRP and S-albumin was found confirming the link between chronic inflammation and malnutrition in chronic renal patients.
Department of Internal Medicine of Pisa, University of Pisa, Italy. v.panichi@int.med.unipi.it
Vincenzo
V
Panichi
Massimiliano
M
Migliori
Stefano
S
De Pietro
Daniele
D
Taccola
Anna Maria
AM
Bianchi
Luca
L
Giovannini
Maria
M
Norpoth
Maria Rita
MR
Metelli
Renza
R
Cristofani
Alberto A E
AA
Bertelli
Giulietta
G
Sbragia
Ciro
C
Tetta
Roberto
R
Palla
R
R
Colombo
D000328:Adult; D002097:C-Reactive Protein / Q000378:metabolism*; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000503:physiopathology; D007677:Kidney Function Tests; D008297:Male; D008875:Middle Aged; D009752:Nutritional Status
D015850:Interleukin-6; D002097:C-Reactive Protein