Biomarker-Based Evaluation of Liver Function: The Emerging Roles of Indocyanine Green and B-Type Natriuretic Peptide

Background: The liver is a key metabolic center, and even the conventional liver function tests are not always able to detect early dysfunction or give real-time measurements of functional capacity. The review examines Indocyanine Green and B-type Natriuretic Peptide as high-sensitivity biomarkers that escape the shortcomings of traditional markers such as ALT, AST and bilirubin. Methods: The review of the literature was carried out using the main medical databases (PubMed, Scopus, and Web of Science) to locate the clinical studies and physiological reviews related to the topic of hepatic biomarkers. We have examined the pharmacokinetics of ICG clearance as a direct reflection of the activity of the hepatocytes and have assessed clinical evidence on BNP as a surrogate of the cardiac-liver axis. These new markers were synthesized to provide comparisons of these new markers against conventional scoring systems such as MELD and Child-Pugh with respect to their usefulness in cirrhosis, hepatocellular carcinoma, and liver transplantation. Results: ICG clearance is a dynamic and real-time measurement of hepatic perfusion and hepatic metabolic reserve, and it is very important in the perioperative time of hepatocellular carcinoma and liver transplantation. On the other hand, high levels of BNP have been found to be related to the extent of portal hypertension and systemic vascular resistance, and it can be used to predict the occurrence of complications including ascites and variceal bleeding. The ICG is a direct evaluation of hepatic fitness, whereas BNP is an assessment of the systemic and cardiovascular load of the liver disease. Conclusion: ICG and BNP are successfully integrated in clinical practice and can help to approach hepatology more holistically. Together with the emerging technologies such as the portable bedside monitors and AI-based analytics, these biomarkers are the future of precision medicine, which can be used to deliver early intervention, tailored therapeutic monitoring, and a higher level of prognostic accuracy in patients with chronic and acute liver pathologies.