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

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.