Foibles and fallacies in the diagnosis of arthritis.

The diagnosis of arthritis is usually made on a clinical basis, and laboratory and x-ray aids are only secondary and sometimes misleading tools. Set forth are 11 common fallacies which often mislead the physician in his interpretation of laboratory and x-ray findings in the study of a patient with arthritis. Included are references to the role of x-ray findings, joint fluid and synovial biopsy findings, hyperuricemia, rheumatoid factor, rheumatoid nodules, sedimentation rate, antinuclear antibodies, and other peripheral blood and urinary findings. In most cases, the astute physician should be able to make an accurate diagnosis when he first sees the arthritic patient; in others, any and all of the laboratory and x-ray parameters mentioned, despite their obvious shortcomings, may be of help in leading to a proper diagnosis. In a small percentage of cases, only the passage of time and further observation of the patient will establish the correct diagnosis.