Comparing Refrigeration to Immediate Room Temperature Testing for Uric Acid Monitoring in Rasburicase-Treated...

Area of Science:

• Clinical Chemistry
• Preanalytical Variables
• Pharmacokinetics

Background:

• Rasburicase maintains activity at room temperature (RT), necessitating cooling for uric acid monitoring specimens.
• Current preanalytical requirements for uric acid testing may hinder compliance.

Purpose of the Study:

• To evaluate if easing preanalytical requirements for uric acid specimen transport and storage improves compliance without compromising accuracy.
• To determine the impact of room temperature versus iced transport on uric acid stability.

Main Methods:

• Fifty pairs of patient specimens were collected for uric acid-level monitoring.
• Specimens were transported and stored either on ice or at room temperature.
• Uric acid levels were tested at three time points: immediately (approx. 45 min), 90 min, and 135 min postcollection.

Main Results:

• Uric acid concentrations showed no significant clinical difference between room temperature and iced specimens when tested within 45 minutes.
• A negative bias was observed in room temperature specimens tested at 90 min (-9.1%) and 135 min (-17.5%).
• Specimens tested 90 minutes postcollection at room temperature showed an additional 24% decrease in uric acid if tested within two rasburicase half-lives; higher rasburicase doses also influenced results.

Conclusions:

• Rapid laboratory testing of uric acid specimens (within 45 minutes) may allow for validation of alternative preanalytical methods, moving away from ice transport.
• Laboratories capable of prompt testing can potentially relax stringent cooling protocols for uric acid monitoring.