During second shift, a green-top specimen was received on ice with a request for uric acid determination. The young processing technician, unfamiliar with this situation, asked a supervisor why the specimen came down on ice. After the ordering provider was contacted, it was determined that a 9-year-old female with lymphoblastic lymphoma was being treated with rasburicase to mitigate potential development of tumor lysis syndrome (TLS) during chemotherapy. Key serum chemistries are shown in Table 1.
What is TLS and how may it present biochemically?
What is rasburicase?
Why was the specimen submitted on ice?
The answers are below.
TLS is a life-threatening condition in which chemotherapeutic treatment causes a massive release of intracellular contents into the bloodstream, commonly resulting in hyperuricemia, hyperkalemia, hyperphosphatemia, and hypocalcemia (1). This often culminates in acute renal failure. Rasburicase is a recombinant urate oxidase administered to convert serum uric acid to the substantially more soluble product allantoin, reducing the risk of renal crystal formation (2). In rasburicase-treated patients, uric acid is vigilantly monitored to verify efficacy. Because the drug's catalytic activity continues postcollection, specimens are iced to minimize ex vivo uric acid conversion, allowing relatively accurate determination (3).
Author Contributions: All authors confirmed they have contributed to the intellectual content of this paper and have met the following 3 requirements: (a) significant contributions to the conception and design, acquisition of data, or analysis and interpretation of data; (b) drafting or revising the article for intellectual content; and (c) final approval of the published article.
Authors' Disclosures or Potential Conflicts of Interest: No authors declared any potential conflicts of interest.
- Received for publication January 30, 2015.
- Accepted for publication April 2, 2015.
- © 2015 American Association for Clinical Chemistry