-lrb- check -rrb- symmetric joint swelling , meaning the same joint must be affected on the left and right sides. ; -lrb- check -rrb- nodules primarily found around the joints that have been identified as rheumatoid. ; -lrb- check -rrb- blood serum that contains rheumatoid factor , an antibody . ; -lrb- check -rrb- hand changes identified through x-rays that are typical of the disease ; must include erosions or decalcification of the bone .