Aspirin (and other salicylates) have varying effects on uric acid. Uric acid is handled by the kidney in a very complicated pattern. After being filtered through the glomerulus, the uric acid ia almost all reabsorbed from the urine, then is secreted back into the urine, with a small amount then being reabsorbed once again. At low aspirin levels (as may occur in persons taking aspirin only occasionally), aspirin blocks secretion of uric acid bythe kidneys and can increase blood uric acid. On the other hand, in high doses (as may be used to treat rheumatoid arthritis), aspirin blocks reabsorption of uric acid by the kidneys to a greater extent than it blocks secretion, leading to lower uric acid.