Liver Function Tests

Order or review ALT, AST, alkaline phosphatase, total and direct bilirubin, prothrombin time, and albumin together when assessing clinically meaningful liver abnormalities. ALT and AST primarily indicate hepatocellular damage; alkaline phosphatase suggests cholestatic or infiltrative disease; bilirubin may reflect cholestasis, impaired conjugation, or biliary obstruction; prothrombin time and albumin contribute to assessment of hepatic function. ScienceDirect+1ScienceDirectEvaluation of Abnormal Liver Biochemical Test ResultsScienceDirectAGA technical review on the evaluation of liver chemistry tests - ScienceDirect

Treat acute liver failure as a critical-care and transplant-center problem. It is dynamic, can require organ support and early liver transplantation, and management must include rapid cause identification plus active prevention and treatment of complications such as intracranial hypertension and sepsis. Therapeutic plasma exchange and, in some centers, early renal replacement therapy are established components of care; artificial liver devices other than these approaches lack supporting evidence for routine practice. ScienceDirectScienceDirectAcute liver failure: A practical update

Use the magnitude of aminotransferase elevation to narrow urgency. ALT or AST elevations greater than 15 times the upper limit of normal are associated with acute viral hepatitis, medications or toxins, ischemic hepatitis, autoimmune hepatitis, Wilson disease, acute bile duct obstruction, acute Budd-Chiari syndrome, or hepatic artery ligation; evaluate these branches without deferring assessment to serial routine monitoring. ScienceDirectScienceDirectAGA technical review on the evaluation of liver chemistry tests - ScienceDirect

A hepatocellular pattern is ALT- and AST-predominant. For mild aminotransferase elevations below 5 times the upper limit of normal, the differential differs according to whether ALT or AST predominates; persistent abnormalities warrant etiologic evaluation rather than attributing the result to metabolic disease solely from the presence of obesity or diabetes. ScienceDirectScienceDirectAGA technical review on the evaluation of liver chemistry tests - ScienceDirect

A cholestatic or infiltrative pattern is alkaline-phosphatase predominant, often with bilirubin elevation. Interpret bilirubin in this setting as a potential marker of cholestasis or obstruction, then determine whether the clinical trajectory suggests acute obstruction, chronic cholestatic disease, infiltrative disease, or congestion. ScienceDirectScienceDirectAGA technical review on the evaluation of liver chemistry tests - ScienceDirect

A mixed pattern should retain both branches in the differential. Avoid assigning causality from a single analyte: aminotransferase elevations reflect injury rather than hepatic reserve, whereas prothrombin time and albumin help assess functional impairment. ScienceDirect+1ScienceDirectEvaluation of Abnormal Liver Biochemical Test ResultsScienceDirectAGA technical review on the evaluation of liver chemistry tests - ScienceDirect

For marked hepatocellular injury, obtain exposure and chronology data before labeling the process idiopathic: prescribed drugs, over-the-counter agents, herbal or dietary supplements, toxins, hypotensive episodes, viral risk, and autoimmune context directly determine the priority differential. Acute viral hepatitis, medications or toxins, ischemic hepatitis, autoimmune hepatitis, Wilson disease, acute bile duct obstruction, and acute Budd-Chiari syndrome are recognized causes of severe aminotransferase elevation. ScienceDirectScienceDirectAGA technical review on the evaluation of liver chemistry tests - ScienceDirect

For suspected drug-induced liver injury, stop or reconsider the implicated exposure according to clinical severity and monitor aminotransferases, total bilirubin, and alkaline phosphatase closely. FDA guidance emphasizes prompt retesting when aminotransferases are markedly abnormal or bilirubin is elevated, because a delay may allow progression when the initial abnormality is the herald of a severe reaction. fdafda[PDF] Guidance for Industry: Drug-Induced Liver Injury - FDA

For metabolic dysfunction-associated steatotic liver disease, establish steatosis and at least one cardiometabolic risk factor while accounting for alcohol exposure and competing liver diseases. MASLD is defined by steatosis with one or more cardiometabolic risk factors in the absence of harmful alcohol intake; terminology now replaces NAFLD with MASLD and NASH with MASH. ScienceDirect+2ScienceDirectEASL Clinical Practice Guidelines on nutrition in chronic liver diseaseWolters KluwerMetabolic dysfunction–associated steatotic liver... : HepatologyGastroenterologyNonalcoholic Fatty Liver Disease Gets Renamed as Metabolic Dysfunction–Associated Steatotic Liver Disease: Progress But With Challenges - Gastroenterology

Repeat testing should be prompt, not routine-delay follow-up, when a potential hepatotoxic reaction is accompanied by aminotransferases above 3 times the upper limit of normal or total bilirubin above 2 times the upper limit of normal. Record the local laboratory reference range and make results immediately available to the treating team when testing occurs outside the primary site of care. fdafda[PDF] Guidance for Industry: Drug-Induced Liver Injury - FDA

For chronic metabolic liver disease, serial aminotransferases do not replace fibrosis risk assessment. Patients with cardiometabolic risk factors, abnormal liver enzymes, or radiologic steatosis should enter a fibrosis-oriented pathway using FIB-4 and transient elastography, because advanced fibrosis predicts liver-related outcomes. ScienceDirectScienceDirectEASL Clinical Practice Guidelines on nutrition in chronic liver disease

In heart failure, interpret serial bilirubin, AST, and ALT in the hemodynamic context because these values predict mortality in acute and chronic heart failure and may reflect congestion rather than the degree of fixed hepatic fibrosis. jaccjaccThe Cardiohepatic Axis in Heart Failure