A method for estimating portal blood flow and hepatic function in a subject is provided. In one example, the STAT test is an in vitro simplified, convenient test intended for screening purposes that can reasonably estimate the portal blood flow from a single blood sample taken 60 minutes after orally administered deuterated-cholate. The test can be administered to a patient having, or suspected of having, Chronic Hepatitis C, Primary Sclerosing Cholangitis (PSC), Non-Alcoholic Fatty Liver Disease (NAFLD), or any chronic liver disease.
