USMLE

Purine Excretion

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Biochemical Pathways
  1. Glycolysis
  2. Citric Acid Cycle (TCA Cycle)
  3. Electron Transport Chain (ETC)
  4. Cori Cycle
  5. De Novo Purine Synthesis
  6. De Novo Pyrimidine Synthesis
  7. Purine Salvage
  8. Purine Excretion
  9. Ethanol Metabolism
  10. Pyruvate Metabolism
  11. HMP Shunt (Pentose Phosphate Pathway)
  12. Galactose Metabolism
  13. Sorbitol (Polyol) Pathway
  14. Urea Cycle
  15. Alanine (Cahill) Cycle
  16. Catecholamine Synthesis & Breakdown
  17. Homocysteine Metabolism
  18. Fatty Acid Synthesis (Citrate Shuttle)
  19. Fatty Acid Breakdown (Carnitine Shuttle)
  20. Propionic Acid Pathway
  21. Fructose Metabolism
  22. Regulation by Fructose-2,6-Bisphosphate (F-2,6-BP)
  23. Glycogenesis

Purine Excretion describes the series of reactions used to excrete the free purine bases, hypoxanthine and guanine, in the event that they are not salvaged (see Purine Salvage).

The pathway begins with the purine bases, hypoxanthine and guanine, which are then converted into xanthine. Xanthine is then converted to uric acid, in a reaction catalyzed by xanthine oxidase. The xanthine oxidase enzyme can be inhibited by the drugs allopurinol and febuxostat. These drugs prevent the formation of uric acid and are commonly used to treat gout.

Uric acid clearance by the kidney plays a major role in purine excretion, and clearance is enhanced by the drugs probenecid and rasburicase. In contrast, aspirin has been shown to reduce clearance of uric acid.

Find Purine Excretion and more Biochemical Pathways among Pixorize's visual mnemonics for the USMLE Step 1 and NBME Shelf Exams.