Use of a 13C-aminopyrine blood test: first clinical impressions

The purpose of this study was to collect initial data to determine the potential clinical usefulness of a 13C-aminopyrine demethylation blood test, and whether additional clinical investigation is warranted. Six dogs, initially suspected of having hepatic disease based on their history, physical examination, imaging studies, general laboratory parameters, or any combination of the above, were enrolled in the study. A baseline blood sample was collected, 2 mg/kg 13C-aminopyrine was administered intravenously, and another blood sample was collected 45 min afterwards. Carbon dioxide was extracted from the blood samples and analyzed using fractional mass spectrometry. Results from the 13C-aminopyrine demethylation blood test were compared to clinical data and histologic findings. Intravenous administration of 13C-aminopyrine leads to a decrease in the percent dose of 13C recovered from dogs with histologically confirmed liver disease. Based on our results, a full-scale investigation of the potential clinical usefulness of a 13C-aminopyrine demethylation blood test for assessment of hepatic function in dogs is warranted.