Abstract
Objective—To determine the optimal sample handling and processing conditions for the carbon 13 (13C)-labeled aminopyrine demethylation blood test (ADBT; phase 1) and determine the reference range for test results (phase 2) in apparently healthy dogs.
Animals—44 apparently healthy dogs (phase 1, 19 dogs; phase 2, 44 dogs).
Procedures—In phase 1, a blood sample from each dog was collected before and 45 minutes after (day 0) IV administration of 13C-labeled aminopyrine (2 mg/kg); aliquots were immediately transferred into tubes containing sodium heparin and hydrochloric acid (samples A and B), sodium heparin alone (samples C, D, and E), or sodium fluoride (sample F). Hydrochloric acid was added to samples C through F at days 7, 14, 21, and 21, respectively. The baseline and 45-minute samples' absolute 13C:12C ratios were determined via fractional mass spectrometry on day 0 (control sample A) or 21 (samples B through F) and used to calculate the percentage dose of 13C recovered in CO2 extracted from samples (PCD). In phase 2, blood samples from each dog were collected into tubes containing sodium fluoride and processed within 3 weeks.
Results—Compared with the control sample value, PCDs for samples C through E differed significantly, whereas PCD in sample F did not. The 13C-ADBT–derived PCD reference range (central 95th percentile) for apparently healthy dogs was 0.08% to 0.2%.
Conclusions and Clinical Relevance—Glycolytic CO2 production in canine blood samples collected during 13C-ADBTs was sufficiently inhibited by sodium fluoride to allow delayed sample analysis and avoid transportation of hydrochloric acid–treated samples.
