A method and a kit for the detection of an elevated risk for, diagnosis of, or the monitoring of treatment of autoimmune disease such as rheumatoid arthritis or osteoarthritis comprises measuring the levels of the serum amino acids wherein a diminished level of two or more of these markers is associated with rheumatoid arthritis or osteoarthritis. Two different sets of amino acids are specified; in claim 1 the set is: phenylalanine, tyrosine, isoleucine, glycine, glutamine, methionine, lysine, asparagine, serine, tryptophan and threonine in claim 8 the set is phenyalanine, tyrosine, isoleucine, leucine, ornithine, proline, glutamate, glycine, glutamine, methionine, aspartate, valine and arginine. The treatment of autoimmune diseases, specifically arthritis, using N-(2-chloro-3,4-dimethoxybenzylideneamino) guanidine (a benzylideneaminoguanidine) is also disclosed.
Diagnosis and treatment of arthritis