Inflammation contributes to low plasma amino acid concentrations in patients with chronic kidney disease.
BACKGROUND
Inflammation and malnutrition are common in chronic kidney disease (CKD) patients, and plasma concentrations of free amino acids (AAs) in these patients are often abnormal. Malnutrition contributes to alterations in AA concentrations.


OBJECTIVE
The objective was to study the effects of inflammation on plasma AA concentrations.


METHODS
Concentrations of plasma AAs, serum albumin, and several inflammatory markers were analyzed in 200 fasting, nondiabetic CKD patients who were close to the start of renal replacement therapy. The nutritional status of these patients was assessed by a subjective global assessment.


RESULTS
The patients with inflammation [C-reactive protein (CRP) concentrations >10 mg/L] or malnutrition had lower AA concentrations than did the patients with no inflammation or malnutrition. The presence of both inflammation and malnutrition was associated with more marked reductions in AA concentrations than was malnutrition alone. Significant inverse correlations were observed between the plasma concentrations of most of the essential and nonessential AAs and inflammatory markers, whereas serum albumin concentrations were positively correlated with several AA concentrations. A stepwise multivariate regression analysis showed that serum CRP concentrations were independently associated with low concentrations of the sums of both nonessential AAs and all AAs. An analysis of all-cause mortality with a Kaplan-Meier test showed that the patients with higher AA concentrations had significantly better survival than did the patients with lower AA concentrations.


CONCLUSIONS
Plasma AA concentrations are low in CKD patients with inflammation and are inversely correlated with concentrations of inflammatory markers. Although inflammation and malnutrition are closely related, CRP concentrations were independently associated with low concentrations of the sums of both nonessential AAs and all AAs, which suggests an independent role of inflammation as a cause of low plasma AA concentrations in CKD patients.
Suliman
Mohammed E
ME
Divisions of Renal Medicine and Baxter Novum, Department of Clinical Science, Karolinska Institutet, Karolinska University Hospital Huddinge, Stockholm, Sweden.
Qureshi
A Rashid
AR
Stenvinkel
Peter
P
Pecoits-Filho
Roberto
R
Bárány
Peter
P
Heimbürger
Olof
O
Anderstam
Björn
B
Rodríguez Ayala
Ernesto
E
Divino Filho
José C
JC
Alvestrand
Anders
A
Lindholm
Bengt
B
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000596:Amino Acids / Q000097:blood*; D002097:C-Reactive Protein / Q000032:analysis; D002908:Chronic Disease; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007249:Inflammation / Q000097:blood*; D007674:Kidney Diseases / Q000097:blood*; D008297:Male; D008875:Middle Aged
D000596:Amino Acids; D002097:C-Reactive Protein