Use of quantitative liver function tests — caffeine clearance and galactose elimination capacity — after orthotopic liver transplantation

Abstract To establish the potential value of quantitative tests of liver function following orthotopic liver transplantation (OLT), a total of 100 determinations of caffeine clearance (CafCl) and galactose elimination capacity (GEC) were made in ten OLT recipients early in the post-operative course (days 2, 4, 6, 8 and 12) and later when clinically stable (3–12 months). Values were compared with a reference range in six normal volunteers in whom it was shown that the standard doses of caffeine (125 mg) and galactose (0.5 g per kg body weight) could be given together without interference. In orthotopic liver transplantation recipients initial GEC and CafCl measurements showed no correlation with peri-operative blood loss, donor ischaemia time, initial bile flow or survival. Throughout the early post-operative period, there were wide inter- and intraindividual variations in both CafCl (17-fold range from 0.16 to 2.7 ml · min −1 · kg −1 ) and GEC (2.4-fold range from 5.1 to 12 mg · min −1 · kg −1 ), but the only correlation of test values with standard liver function test results was between GEC and γ-glutamyltranspeptidase. However, GEC values fell by 19% during periods of acute rejection and there was an inverse correlation of GEC with white cell count probably related to sepsis. There was no consistent profile of changing CafCl or GEC values during the post-operative course with median CafCl values (0.87–1.2 ml · min −1 · kg −1 ) never significantly different from those in volunteers (1.1 ml · min −1 · kg −1 ) but median GEC results (ranging from 7.3 mg · min −1 · kg −1 at day 12 to 8.2 mg · min −1 · kg −1 at day 4) significantly lower than in normal volunteers (9.5 mg · min −1 · kg −1 ) at all times including late follow-up (7.7. mg · min −1 · kg −1 ) when six patients were clinically well. Mean CafCl increased 46% in four patients who were smoking at follow-up, while the introduction of new drug therapies was associated with decreases up to 59% for nine of eleven drugs, with corresponding changes for GEC never exceeding 11%. CafCl and GEC were of little benefit in differential diagnosis of early post-operative complications in this small heterogeneous group of orthotopic liver transplantation recipients, with interindividual variability and susceptibility to modulation by factors other than liver function (e.g., drug ingestion) severely limiting the value of these procedurally complex tests.