A 42-year-old female presents with acute oliguric renal failure 3 days after initiation of chemotherapy for newly diagnosed non-Hodgkin lymphoma. Urine sediment analysis demonstrates amber crystals shaped like hexagonal plates, barrels, and needles.
Which of the following therapies is LEAST likely to be beneficial in the prophylaxis and management of this nephropathy?
A. RasburicaseCorrect Answer: D
This patient most likely has tumor lysis syndrome (TLS) and AKI as a consequence. Uric acid precipitation in the renal tubules results in AKI in patients with acute urate nephropathy. This could occur due to overproduction and excretion of the excess uric acid, particularly after chemotherapy or radiation in patients with lymphoma, leukemia, or other myeloproliferative diseases. That being said, patients with a large tumor burden could present with spontaneous TLS, without antecedent chemotherapy.
Uric acid nephrolithiasis may manifest with flank pain if there is renal pelvic or ureteral obstruction. The diagnosis should be suspected in presence of acute renal failure in patients at high risk for TLS (increased tumor burden, volume depletion, preexisting CKD, and hyperuricemia). Uric acid nephropathy is associated with a marked hyperuricemia, with plasma urate levels >15 mg/dL. Urinalysis may show uric acid crystals.
Prophylaxis in patients at high risk for TLS involves the use of allopurinol or febuxostat (xanthine oxidase inhibitors) along with rasburicase (recombinant urase oxidase that catalyzes conversion of uric acid to allantoin). The cornerstone of treatment of TLS and urate nephropathy is aggressive intravenous hydration to ensure adequate renal blood flow and glomerular filtration. Volume expansion has shown to delay and reduce the need for renal replacement therapy in these patients. Sodium bicarbonate infusion and alkalization of urine could reduce solubility and increase the risk of calcium phosphate precipitation. Further rise in serum pH with bicarbonate infusion could result in exacerbation in hypocalcemia. For these reasons, urinary alkalinization is not recommended in this setting.
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