The determination of dehydroascorbic acid and ascorbic acid in the serum and synovial fluid of patients with rheumatoid arthritis (RA)

Abstract

Using a novel high performance liquid chromatography (HPLC) determination of ascorbic acid and dehydroascorbic acid, we have measured the relative amounts of ascorbate and dehydroascorbate in 20 normal controls and in paired sera and synovial fluid from 13 patients with rheumatoid arthritis (RA). In complete contrast to previous published findings we were able to detect dehydroascorbate in normal human sera (12.0 +/- 3.7 mumol/l), while the mean and range of ascorbate measured in normals was 69.6 +/- 20.6 mumol/l. These findings were completely reversed in rheumatoid sera (21.8 +/- 8.6 mumol/l and 5.1 +/- 5.0 mumol/l for dehydroascorbate and ascorbic acid respectively). In several rheumatoid sera no ascorbate could be detected. In paired synovial fluid and serum samples, there was always more dehydroascorbate detected in synovial fluids than in the corresponding sera (p less than 0.01). The data suggests that the reduced level of ascorbate and increased level of dehydroascorbate may be a reflection of the increased antioxidant and free-radical scavenging activity of the vitamin in RA, especially within the inflamed joint.