Study on the diagnosis of gout with xanthine and hypoxanthine

Background Hyperuricemia is the only biochemical index in the classification of acute gouty arthritis in American Rheumatism Association 1977 and the main basis of clinical diagnosis for most doctors. However, nearly half of the time gout occurs without hyperuricemia, especially in an acute attack，which leads to an urgent need to find a new substitute diadynamic criteria of gout. Xanthine and hypoxanthine, as precursors of uric acid, have been reported to be high in gout patients with hyperuricemia and presumed to be gout biomarkers. Objectives To further explore the possibility of xanthine and hypoxanthine to be gout biomarkers as substitutes for uric acid. Methods A reversed‐phase HPLC‐UV method was employed for simultaneous quantitative detection of uric acid (UA), xanthine (X), and hypoxanthine (HX) in gout patients’ (with and without hyperuricemia) and healthy persons’ serum. Results The xanthine and hypoxanthine concentrations in gout patients with hyperuricemia and without hyperuricemia are higher than in healthy persons with a P < 0.001. Conclusions This study supplements previous researches by confirming that xanthine and hypoxanthine are significantly elevated in gout patients’ serum especially in patients’ with normouricemia, which supported xanthine and hypoxanthine may have clinical application for the diagnosis of gout.