Blood tests

• The following enzymes (GGT, AST, ALT, ALP, LDH) are in different cells in the body, but they are most concentrated inside hepatocytes.  Presence of these enzymes in high levels in the blood suggest hepatocyte leakage and lysis that has lead to the release of hepatic enzymes into the bloodstream.
• Hepatic function is measured by the amount of albumin in reference to the levels of total protein consumed.  This is an excellent way to measure hepatocyte function, as albumin is only made by hepatocytes, using the proteins made available from diet (measured by total protein).  Hepatic function is also measured by the amount of total and conjugated bilirubin (direct bilirubin) in the blood as a functional liver will have low levels of hydrophobic unconjugated bilirubin (indirect bilirubin) in the blood.
• Hepatic function is also assessed by how well ammonia is removed.  Low levels of ammonia in the blood suggests functional hepatocytes.

Coagulation panel

• platelet number – the number of platelets indicates if there is a problem with either production (i.e. lack of the liver hormone thrombopoietin),  accumulation in the spleen due to spelnomegaly (i.e. due to portal hypertension), or due to destruction (i.e. tortuous path of platelet flow in fibrotic liver)
• Clotting time:  a deficiency in any component of coagulation will result in a prolonged clotting time (PTT/INR)

Complete Blood Count (CBC)

Ultrasound

^{Use of Ultrasound in liver disease by Ken Marken, interviewed by Jennifer Kong under a CC-BY-NC license}

Liver biopsy

Section Summary

To assess the health of the liver, the liver can be both visualized and liver products & wastes measured to determine function.  The liver panel are blood tests which examine the extent of hepatocyte damage by measuring the presence of intra-hepatocyte enzymes floating around in the peripheral circulation:  an elevated presence of these hepatic enzymes leakiness or lysis of hepatoctyes.  Hepatocyte products such as albumin can be measured in the peripheral blood to determine the liver’s ability to synthesize plasma proteins.  As hepatocytes are responsible for most clotting factors and starting platelet synthesis, clotting times are also useful to determine liver function.  Similarly, the presence of undesired wastes such as ammonia or unconjugated (indirect) bilirubin will determine the liver’s function.   Liver can be visualized by ultrasound to determine size, shape, presence of nodules, and blood/bile flow.  Ultrasound is also used when obtaining a piece of liver for histopathological analysis (i.e. liver biopsy).  Liver biopsy is the definitive diagnostic test for liver disease and cirrhosis.

Review Questions