blood xenobiotic metabolism measurement calculated liver physiological measurement hepatic extraction fraction 2021-10-07T18:23:40Z CMO:0003842 CMO:0003846 HEF PMID:30208622 This is the fraction of a drug entering the liver from the blood which is irreversibly removed (extracted) during one pass of the blood through the liver. The hepatic extraction fraction (HEF) depends on the hepatic blood flow, uptake into hepatocytes, and enzyme metabolism. HEF can be calculated using deconvolution analysis of the liver using scintigraphic data. clinical_measurement_ontology hepatic extraction ratio slaulede