[Serum vitamin B12 levels of the patients with chronic rheumatoid arthritis].
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood*; D002908:Chronic Disease; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D014805:Vitamin B 12 / Q000097:blood*
D014805:Vitamin B 12