Guidelines for Complications of Cancer Treatment Vol VIII Part B

hyperuricemia (> 7.5 mg/dL), treatment with rasburicase ispreferred (level of evidence: II; grade ofrecommendation: B).Allopurinol can also cause an increase in serum levels andcrystal deposition of the purine precursors xanthine andhypoxanthine, which can result in acute obstructive uropathy.Because allopurinol is excreted by the kidneys, a dosereduction of 50% is recommended in patients with renalinsufficiency. The guidelines for allopurinol dosages andadministration for adult patients are the same as those forpediatric patients. Treatment may be started 1 to 2 days beforethe start of induction chemotherapy and may be continued forup to 3 to 7 days afterwards, based on the ongoing risk of TLSdevelopment (level of evidence: II; grade ofrecommendation: B).Recombinant Urate OxidaseUrate oxidase converts uric acid into allantoin, which is fiveto 10 times more soluble in urine than uric acid. A recombinantform of urate oxidase with a high specific activity is available.Rasburicase is much more effective in reducing the level ofuric acid, creatinine and achieving the control of othermetabolites involved in tumour lysis syndrome. The use ofrecombinant urate oxidase (rasburicase) is recommended forthe treatment of pediatric patients with hyperuricemiaassociated with LTLS or CTLS, or in the initial managementof patients considered to be at high risk of developing TLS(Table 4).In addition, for patients in the intermediate-risk group,rasburicase is recommended if urate nephropathy developsdespite prophylactic treatment with allopurinol (level ofevidence: II; grade of recommendation: B). Rasburicase iscontraindicated in patients with a known G6PD deficiencyand in pregnant or lactating females. Screening for G6PD425