Uric acid is a chemical that is produced by the body as the final product of purine metabolism. Its chemical structure is shown in Figure 1. Everyone makes small amounts of uric acid, but people with Lesch-Nyhan disease make too much.
Figure 2 shows uric acid levels found in the blood. Normal people have levels that fall in the blue zone. In general, children have lower levels than adults, so the blue zone changes with age. The yellow circles show serum uric acid levels in individuals with Lesch-Nyhan disease. Most of these are outside of the normal range, though some are only a little bit high.
Most of the uric acid in the blood is filtered through the kidneys and then dumped into the urine. As a result, urine uric acid levels are also high in people with Lesch-Nyhan disease. Figure 3 shows uric acid levels in the urine. Normal people have levels that fall in the gray zone. The yellow circles show urine uric acid levels in individuals with Lesch-Nyhan disease, and most of these are again outside the normal range.