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 µmol/l in controls versus 5 µmol/ (group 1), 9 µmol/l (group 2), and 20 µmol/l (group 3). Met concentrations were 26 µmol/l in controls versus 26 µmol/l (group 1), 66 µmol/l (group 2), and 281 µmol/l (group 3). Cys concentrations were 10 µmol/ in controls versus 98 µmol/l (group 1), 54 µmol/l (group 2), and 122 µmol/l (group 3). Ser concentrations were 88 µmol/ in controls versus 153 µmol/l (group 1), 239 µmol/l (group 2), and 240 µmol/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 µmol/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.