Quantitative assessment of hepatic function by breath analysis after oral administration of (14C)aminopyrine.

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 less than 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 equals 0.92), serum albumin (r equals 0.75), and retention of bromsulphalein (r equals 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.