Optimization of sample handling and processing for the carbon 13-labeled aminopyrine demethylation blood test and determination of a reference range for test results in healthy dogs.
OBJECTIVE
To determine the optimal sample handling and processing conditions for the carbon 13 ((13)C)-labeled aminopyrine demethylation blood test (ADBT; phase 1) and determine the reference range for test results (phase 2) in apparently healthy dogs.


METHODS
44 apparently healthy dogs (phase 1, 19 dogs; phase 2, 44 dogs).


METHODS
In phase 1, a blood sample from each dog was collected before and 45 minutes after (day 0) IV administration of (13)C-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 (13)C:(12)C 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 (13)C recovered in CO(2) 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 (13)C-ADBT-derived PCD reference range (central 95th percentile) for apparently healthy dogs was 0.08% to 0.2%.


CONCLUSIONS
Glycolytic CO(2) production in canine blood samples collected during (13)C-ADBTs was sufficiently inhibited by sodium fluoride to allow delayed sample analysis and avoid transportation of hydrochloric acid-treated samples.
DeBiasio
John V
JV
Department of Small Animal Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77845, USA.
Steiner
Jörg M
JM
Suchodolski
Jan S
JS
Read
Sarah A
SA
D000633:Aminopyrine N-Demethylase / Q000008:administration & dosage / Q000097:blood*; D000818:Animals; D002247:Carbon Isotopes / Q000008:administration & dosage / Q000097:blood*; D004285:Dogs; D006403:Hematologic Tests / Q000379:methods / Q000662:veterinary*; D006851:Hydrochloric Acid; D007275:Injections, Intravenous; D012016:Reference Values; D012969:Sodium Fluoride; D013048:Specimen Handling / Q000379:methods / Q000662:veterinary*
D002247:Carbon Isotopes; D012969:Sodium Fluoride; D000633:Aminopyrine N-Demethylase; D006851:Hydrochloric Acid