Blanka Stiburkova, Lenka Hasikova, Petr Kozlik, Kveta Kalikova, Marketa Pavlíkova
Affiliation(s):
Institute Of Rheumatology
Background and Objectives: Uric acid (UA) can be non-enzymatically oxidized into allantoin and other products by reactive oxygen species under conditions of increased oxidative stress. This study measured serum allantoin levels and allantoin/uric acid ratios in patients with gout to assess the association with disease severity and cardiovascular comorbidities.
Methods: Clinical data (number and types of antihypertensive medications, presence of tophi, and number of gout attacks over the past 5 years) and serum samples were obtained from 154 patients with gout, 55 patients with asymptomatic hyperuricemia, and 47 healthy controls (Bak of Biological Materials Institute of Rheumatology). Allantoin quantification was performed using a previously described, fully validated ultra-high-performance liquid chromatography-tandem mass spectrometry method. Serum concentrations of CRP, creatinine, uric acid, and lipid profile were also measured.
Results: Serum allantoin and the allantoin/uric acid ratio were significantly lower in controls than in both hyperuricemia (p < 0.001) and gout patients (p < 0.001). However, there was no statistically significant difference between hyperuricemia and gout patients. Serum allantoin and the allantoin/uric acid ratio values were significantly increased in patients with tophaceous gout compared to those without tophi (p = 0.009 and p = 0.022).
In patients who reported a gouty attack within the last five years, allantoin levels were significantly elevated (p = 0.05), showing a slight upward trend with the number of attacks. Patients with gout and concomitant arterial hypertension exhibited significantly increased levels of allantoin and allantoin/uric acid ratios (p = 0.008 vs. p = 0.013). The allantoin and the allantoin/UA ratio were positively associated with C-reactive protein (p < 0.001).
Conclusion: Serum allantoin and the allantoin/UA ratio reflect oxidative stress and disease severity in gout and identify patients with increased cardiovascular risk, particularly those with hypertension or tophaceous disease.