XDH and hyperuricemia: However, two recent trials, known as Prevention of Early Renal Loss (PERL) in diabetes16 and the Controlled Trial of Slowing of Kidney Disease Progression from the Inhibition of Xanthine Oxidase (CKD-FIX)17, reported no benefit of allopurinol in slowing kidney progression in patients with CKD and asymptomatic hyperuricemia.