Folate, vitamin B12, and sulfur amino acid levels in patients with renal failure

Abstract

We examined the plasma profile of sulfur amino acids (SAA) in patients with chronic renal failure (CRF) and looked for any correlation with serum folate (FA) and/or vitamin B12. Group 1 comprised 9 patients with CRF and glomerular filtration rate (GFR) >20 ml/min per 1.73 m2, 9 patients with GFR<20 ml/min per 1.73 m2 comprised group 2, and 14 patients on hemodialysis group 3. The control group comprised 16 healthy children. Homocysteine (Hcy), methionine (Met), cysteine (Cys), and serine (Ser) were measured with gas chromatography. FA and vitamin B12 were measured using enzymatic immunoassay. Median SAA concentrations were significantly lower in controls than in the three groups of patients. Hcy concentrations were 0.8 micromol/l in controls versus 5 micromol/(group 1), 9 micromol/l (group 2), and 20 micromol/l (group 3). Met concentrations were 26 micromol/l in controls versus 26 micromol/l (group 1), 66 micromol/l (group 2), and 281 micromol/l (group 3). Cys concentrations were 10 micromol/ in controls versus 98 micromol/l (group 1), 54 micromol/l (group 2), and 122 micromol/l (group 3). Ser concentrations were 88 micromol/ in controls versus 153 micromol/l (group 1), 239 micromol/l (group 2), and 240 micromol/l (group 3). The median concentrations of FA were lower in controls than in groups 2 and 3: 5.5 ng/ml versus 8 ng/ml and 15 ng/ml, respectively. Vitamin B12 concentrations did not differ between groups. Vitamin levels did not correlate with SAA. The only difference between patients with Hcy levels in the lower and upper quartile was in Met concentration (38 vs. 263 micromol/l, P<0.02) and GFR (P<0.01). In conclusion, patients with CRF had higher SAA concentrations than healthy children. FA concentrations are higher in CRF patients than in healthy children but did not correlate with concentrations of SAA.