Plasma amino acid level in rheumatoid arthritis and ankylosing spondylitis and its variation during age

28 plasma amino acids of 40 female patients with rheumatoid arthritis (RA), 24 male patients with ankylosing spondylitis (ASp) and 19 controls (14 females and 5 males) were investigated. In RA-patients 19 amino acids showed statistically significant differences to healthy people of which 18 were decreased. In ASp-patients 14 amino acid concentrations were statistically altered whereby 10 showed enhanced values. In female RA-patients and controls a linear dependency between distinct amino acids (threonine, glutamic acid, proline, alanine, citrulline, tyrosine, phenylalanine, ornithine, lysine and 3-methylhistidine) - and advanced age could be demonstrated.