Quantitative Assessment of Hepatic Function by Breath Analysis after Oral Administration of [¹⁴C]aminopyrine

Abstract

The rate of hepatic metabolism of dimethylaminoantipyrine (aminopyrine), which occurs primarily through N-demethylation, was assessed by measurement of the specific activity of ¹⁴CO₂ excreted in breath samples obtained 2 hours after oral administration of a trace dose of [¹⁴C]aminopyrine. The percentage of administered ¹⁴C excreted in ¹⁴CO₂ in 2 hours was 7.0 ± 1.3 (SD)% in control patients, and significantly less (P < 0.01) in patients with portal cirrhosis (2.6 ± 1.2%), fatty liver (4.7 ± 1.1%), hepatitis (2.6 ± 1.4%), and hepatic malignancy (3.5 ± 1.8%). In 16 of 24 subjects with cholestasis not caused by malignant disease the mean ¹⁴CO₂ excretion was normal. The ¹⁴CO₂ excretion in patients with portal cirrhosis correlated highly with aminopyrine metabolic clearance rate (r = 0.92), serum albumin (r = 0.75), and retention of bromsulphalein (r = 0.73). Abnormal ¹⁴CO₂ excretion returned to normal in patients with hepatitis, when the hepatitis resolved. The data suggest that the aminopyrine breath test is a safe, simple, qualitative and quantitative liver function test.