Bentonite Flocculation Test in Rheumatoid Arthritis

The bentonite flocculation test was applied to the serums of 48 patients who satisfied all the clinical criteria for rheumatoid arthritis. Positive results were obtained in 40 and falsenegatives in 8 (17%). Of 12 patients with the probable diagnosis of rheumatoid arthritis, 4 gave positive results, and 8 (67%) gave false negatives. The test was also applied in other rheumatic conditions, with negative results in 17 out of 19 cases of rheumatoid spondylitis and negative results in all of 15 cases of osteoarthritis with fibrositis, indicating that these two conditions differ significantly from rheumatoid arthritis. Applied to 68 other patients with symptoms involving the joints, the test gave negative results in all but four (2 out of 10 patients with gout, 1 out of 4 with lupus erythematosus, and 1 out of 12 with essential hypertension). The bentonite flocculation test is comparatively simple and inexpensive, and these data indicate that it is a useful laboratory aid in the diagnosis of rheumatoid arthritis.