Comparing Refrigeration to Immediate Room Temperature Testing for Uric Acid Monitoring in Rasburicase-Treated Patients.
Author(s): Lin L, Filtz M, Wilson J, Errigo R, Zuromski LM, Nguyen Sorenson A, Young BA
Publication: J Appl Lab Med, 2024, Vol. , Page
PubMed ID: 39691998 PubMed Review Paper? No
Purpose of Paper
This paper compared uric acid levels in case-matched serum specimens that were chilled during transport, centrifugation, and up to 135 min of storage with those transported, centrifuged and stored at room temperature. Specimens were collected from patients taking rasburicase for tumor lysis syndrome the impact of timing relative to infusion with rasburicase and rasburicase dosage on the stability was also investigated.
Conclusion of Paper
Uric acid levels were very similar between case-matched serum specimens that were transported and processed chilled (ice/4°C, control) and those transported and processed at room temperature (Deming regression R2=0.99). When specimens were stored chilled, uric levels remained comparable for up to 135 min post-venipuncture; but, when the specimens were processed and stored at room temperature, uric acid levels decreased slightly compared to control specimens processed (at both the 90 and 135 min timepoint) and bias increased with the duration of room temperature storage. Using a stepwise regression analysis, rasburicase dose and the number of binned rasburicase half-lives since the last infusion were found to explain ~50% of the variability in the decrease in uric acid in specimens stored at room temperature for 90 min. Specimens that were taken <2 half-lives post-infusion lost 24% more uric acid during 90 min of room temperature processing and storage than specimens obtained >2 half-lives post-infusion. The percentage of specimens that were processed and stored at room temperature and exceeded the total error allowance (17%) was higher among specimens that were taken <2 half-lives post infusion than those taken >2 half-lives post-infusion at the initial (5% versus 0%), 90 min (41% versus 7%), and 135 min (68% versus 15%) timepoints. An 18% larger decrease in uric acid levels during 90 min of room temperature processing and storage was also found in specimens from patients who received a 6 mg dose of rasburicase compared to specimens from patients who received a 3 mg dose.
Studies
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Study Purpose
This study compared uric acid levels in case-matched serum specimens that were transported, centrifuged and stored for up to 135 min chilled with those transported, centrifuged and stored at room temperature. The impact of timing relative to infusion with rasburicase as well as the dosage of rasburicase on the stability was also investigated. Fifty blood specimens were collected in lithium heparin plasma separator tubes from 19 patients taking rasburicase (7 patients was taking 6 mg and 12 patients were taking 3 mg) for tumor lysis syndrome. One specimen of each case-matched pair was collected into a pre-chilled tube and transported on ice, centrifuged at 4°C (duration and speed not specified), and immediately analyzed, whereas the other tube was transported and centrifuged at room temperature. Uric acid levels were quantified in serum using an Abbott Architect c (interassay %CV of 1.7) or an Abbott Alinity c analyzer (inter-assay %CV of 2.1). The authors selected a total allowable error threshold of <17%.
Summary of Findings:
Uric acid levels were very similar between case-matched serum specimens that were transported and processed chilled (ice/4°C, control) and those transported and processed at room temperature (Deming regression R2=0.99), with a bias of only -2.4% and no clinically significant differences observed at any of the uric acid concentrations examined (1-12 mg/dL). When specimens were stored chilled, uric levels remained comparable for up to 135 min post-venipuncture (Deming regression R2=1.00, bias -1.7% versus immediately processed and chilled specimens). However, when the specimens were processed and stored at room temperature, uric acid levels decreased slightly compared to control specimens processed immediately (Deming regression R2=0.95 after 90 min and R2=0.84 after 135 min). The bias compared to control specimens increased with room temperature storage (-9.1% after 90 min, -17.5% after 135 min). Importantly, uric acid levels decreased by >10% in 16 of the 50 specimens processed and stored at room temperature for 90 min relative to case-matched controls processed and analyzed immediately. Using stepwise regression analysis, rasburicase dose and the number of binned rasburicase half-lives since the last infusion were found to explain ~50% of the variability in the decrease in uric acid in specimens stored at room temperature for 90 min. Specimens that were taken <2 half-lives post-infusion lost 24% more uric acid during 90 min of room temperature processing and storage than in specimens obtained >2 half-lives post-infusion. The percentage of room temperature processed and stored specimens that exceeded the total error allowance (17%) was higher among specimens that were taken <2 half-lives post-infusion than those taken >2 half-lives post-infusion at the initial (5% versus 0%), 90 min (41% versus 7%), and 135 min (68% versus 15%) timepoints. An 18% larger decrease in uric acid levels during 90 min of room temperature processing and storage was also found in specimens from patients who received a 6 mg dose of rasburicase compared to specimens from patients who received a 3 mg dose.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Neoplastic - Not specified
- Other diagnoses
Platform:
Analyte Technology Platform Small molecule Clinical chemistry/auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Preaquisition Other drugs 6 mg rasburicase
3 mg rasburicase
Biospecimen Acquisition Time of biospecimen collection >2 half-lives post infusion
<2 half-lives post infusion
Storage Specimen transport duration/condition On ice
At room temperature
Storage Storage temperature At room temperature
On ice/4°C
Storage Storage duration ~45 min
90 min
135 min