Indocyanine green clearance test

FIGURE 7.4 Relationship between Child-Pugh stages of liver disease severity and extent of impairment in antipyrine breath test (ABT), galactose elimination capacity (GEC), sorbitol clearance, and indocyanine green clearance (ICG). (Adapted from data published by Herold C, Heinz R, Niedobitek G et al. Liver 2001 21 260-5.)... 

Several tests have been developed to quantify actual liver function, including indocyanine green (ICG), aminopyrine and bromosulpho-thalein. The principle of these tests is to determine whether hepatic blood flow or cell function is reduced by administering a chemical which is exclusively taken up or metabolised by the liver. For example, in the ICG clearance test the ICG is a non-toxic chemical solely taken... 

Indocyanine green was introduced by J. Caesar et al. in 1961 as a liver function test. Anionic tricarbocyanine dye is referred to as an ideal test substance (1.) it is tolerated very well there have been no reports of any incidents so far, and even paravenous injection is tolerated (2.) it is excreted unchanged by hepatocytes in the bile as there is no bio transformation - this is why ICG clearance is valid as a measure of hepatocellular uptake and transport processes (3.) there is no interference with drugs (except rifamycin), haemolysis, bilirubin (up to approx. 4 mg/dl) or hyperlipidaemia (4.) the substance is not subject to the enterohepatic circulation (J.) the rapid elimination, which depends on hepatic perfusion ( flow-limited ), allows the calculation of the hepatic flow volume as a whole based on ICG clearance (6.) the method is simple to perform. 

Xenobiotics are foreign substances that are cleared and metabolized by the liver and some have been used as tests of liver function. For example, certain Hpophilic substances such as bromsulfophthalein (BSP), indocyanine green (ICG), aminopyrine, caffeine, Udocaine, and rose Bengal are excreted into bile as the intact parent compound, its conjugates, or both. The clearance of these xenobiotics by the liver is normally very rapid, and it is beUeved that uptake by hepa-... 

Clearance tests of liver function assess a number of physiologic activities including hepatic uptake, hepatic metabolism, and hepatic excretion. Typical clearance tests of liver function include indocyanine green (ICG), antipyrine clearance test and C aminopyrine breath test. These tests give an estimation of the ability of the liver to extract and detoxify exogenous toxins (xenobiotics). Measuring the excretion of endogenously produced serum bile acids is an additional measure of hepatic clearance and has been used as a sensitive measure of early solvent hepatotoxicity." "... 

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