Total plasma homocysteine and related amino acids in end-stage renal disease (ESRD) patients measured by gas chromatography-mass spectrometry - Comparison with the Abbott IMx homocysteine assay and the HPLC method
Ji. Sigit et al., Total plasma homocysteine and related amino acids in end-stage renal disease (ESRD) patients measured by gas chromatography-mass spectrometry - Comparison with the Abbott IMx homocysteine assay and the HPLC method, CLIN CH L M, 39(8), 2001, pp. 681-690
Increased concentrations of homocysteine probably contribute to the high ca
rdiovascular morbidity and mortality in hemodialysed end-stage renal diseas
e (ESRD) patients and are determined by a variety of factors such as age, r
esidual renal function, and vitamin status. Fasting plasma concentrations o
f total homocysteine, methionine, cysteine, and cystathionine were determin
ed by gas chromatography-mass spectrometry (GC-MS) in 131 ESRD patients rec
eiving daily oral folate (160-320 mug) and vitamin B-6 (10-20 mg) supplemen
ts. Concentrations of homocysteine determined by GC-MS were compared with t
hose measured by high-performance liquid chromatography (HPLC) and an immun
ofluorescence method (IMx analyzer) using Passing-Bablok regression analysi
s. Mean plasma concentration of total homocysteine determined by GC-MS (28.
7 +/-1.9 mu mol/l [mean +/- SD]) was significantly lower than that determin
ed by HPLC (34.0 +/- 04.5 mu mol/l; p<0.001) or IMx (32.4<plus/minus>03.9 m
u mol/l; p<0.001). A close correlation existed between GC-MS and HPLC (r=0.
931; Y=1.203 x+0.279) and GC-MS and IMx (r=0.896; Y=1.105 x+0.766). Linear
regression analysis showed positive correlations between plasma concentrati
ons of homocysteine and cysteine (r=0.434; p<0.001) and homocysteine and cy
stathionine (r=0.187; p=0.032). Plasma concentrations of homocysteine corre
lated negatively with folate (r=-0.281; p=0.001) and vitamin B-12 (r=-0.229
; p=0.009). GC-MS proved to be a sensitive and reliable method for the dete
rmination of total plasma homocysteine and related amino acids. Despite vit
amin supplementation, ESRD patients requiring chronic maintenance hemodialy
sis, have high plasma concentrations of homocyst(e)ine which seems to be me
tabolized mainly within the transsulfuration pathway, while remethylation t
o methionine seems to be disturbed.