<p><strong>In adult and pediatric patients with uric acid stones, clinicians should not offer xanthine oxidase inhibitors (e.g., allopurinol or febuxostat) as first-line therapy. (<em>Expert Opinion</em>) </strong></p>
Discussion
Discussion
<p>Most patients with uric acid stones form their stones as a result of a low urinary pH rather than excessive urinary excretion of uric acid.<sup>209</sup> Consequently, lowering urinary uric acid excretion with xanthine oxidase inhibitors (i.e., allopurinol or febuxostat) does not effectively reduce uric acid stone recurrence. In one retrospective study, six men with gouty arthritis treated with allopurinol prescribed to lower serum uric acid continued to experience uric acid stone recurrence until urine alkalinization with potassium citrate was instituted.<sup>207</sup> After increasing urinary pH, xanthine oxidase inhibitors may be used in patients with significant hyperuricosuria/high urate turnover (e.g., tumor lysis syndrome, myeloproliferative disorders) and persistent uric acid stone formation.<sup>210</sup></p>