ABSTRACT
OBJECTIVE: To evaluate glycine conjugation of para-aminobenzoic acid (PABA) to the hippurated metabolites, para-aminohippuric acid (PAHA), and para-acetamidohippuric acid (PAAHA) as a quantitative liver function test in patients with liver disease. DESIGN AND METHODS: Serum concentrations of PABA and metabolites were measured by high pressure liquid chromatography in 24 controls and 50 patients with hepatobiliary disease. RESULTS: Hippurate formation was significantly decreased in all patient groups with chronic liver disease versus controls. The hippurate ratio (% hippurated metabolites formed) correlated with severity of disease, serum albumin, and factor VII concentrations. PAHA concentration was a better prognostic indicator than factor VII concentrations in patients with acute liver disease; concentrations of zero correctly predicted a poor outcome in patients with fulminant liver failure. CONCLUSIONS: Glycine conjugation of PABA may be useful as a quantitative liver function test in patients with hepatobiliary disease and as a prognostic index in patients with fulminant liver failure.
Subject(s)
4-Aminobenzoic Acid/metabolism , Glycine/metabolism , Liver Diseases/diagnosis , Liver Function Tests/methods , 4-Aminobenzoic Acid/blood , Acute Disease , Adolescent , Aminohippuric Acids , Child , Child, Preschool , Chronic Disease , Factor VII/metabolism , Female , Hippurates/blood , Hippurates/metabolism , Humans , Infant , Liver Diseases/metabolism , Male , Predictive Value of Tests , Prognosis , Serum Albumin/metabolism , p-Aminohippuric Acid/blood , p-Aminohippuric Acid/metabolism , para-AminobenzoatesABSTRACT
This is a high-performance liquid-chromatographic method for measuring p-aminobenzoic acid (PABA) and its metabolites in plasma or serum. Samples are deproteinized, then extracted with organic solvents before chromatography. For quantification, the peak height of the individual compound is compared with that of the internal standard. Analytical recoveries ranged from 41% to 100%, depending on the compound studied. Comparison of patients' samples after oral administration of either N-benzoyl-L-tyrosyl-p-aminobenzoic acid or free PABA revealed that PABA is extensively metabolized and conjugated to either p-acetamidobenzoic acid, p-aminohippuric acid, or p-acetamidohippuric acid. PABA concentrations in serum as measured with the Bratton-Marshall ultraviolet spectrophotometric procedure would appear predominantly to reflect measurements of metabolites, with only a minor contribution from PABA itself.
Subject(s)
4-Aminobenzoic Acid/blood , Aminobenzoates/blood , 4-Aminobenzoic Acid/pharmacokinetics , Chromatography, High Pressure Liquid/methods , Humans , Reference Values , para-AminobenzoatesABSTRACT
We assessed the diagnostic capability of the bentiromide test using a high-pressure liquid-chromatography method to analyze p-aminobenzoic acid and its metabolites in plasma as an indirect measure of exocrine pancreatic function. Mean total amine concentration in pancreatic-insufficient subjects was significantly lower than in control subjects. There were 3 of 15 false-negative results and no false-positive results. We conclude that this chromatographic method is an effective means of analyzing p-aminobenzoic acid and its metabolites after ingestion of bentiromide.