GGT and AP (Cholestatic Liver Enzymes)

Several researches have came to the same conclusion- high levels of GGT and AP could be possible sign of  blockage of the bile ducts, or of possible injury to, or inflammation of, the bile ducts. This liver injury is known as cholestatic liver injury. Cholestasis can be:

1. Intrahepatic - intrahepatic cholestasis refers to bile duct blockage or injury within the liver. It occurs in people with primary biliary cirrhosis or liver cancer
2. Extrahepatic - this type of cholestasis refers to bile duct blockage or injury occurring outside the liver. It may also occur in people with gallstones.

When a blockage or inflammation of the bile ducts occurs, the GGT and AP can overflow and seep out of the liver and into the bloodstream. GGT is found predominantly in the liver. AP is mainly found in the bones and the liver but can also be found in many other organs, such as the intestines, kidneys, and placenta.  People who smoke cigarettes appear to have higher AP and GGT than nonsmokers for reasons that are still unknown.

Normal levels of AP range from 35 to 115 IU/L and normal levels of GGT range from 3 to 60 IU/L. Some causes of elevated AP and/or GGT include the following:

• Primary biliary cirrhosis
• Primary sclerosing cholangitis
• Nonalcoholic fatty liver disease   
• Alcoholic liver disease
• Liver tumors
• Drug-induced liver disease
• Gallstones

Liver function test

What exactly is a liver function test? Blood samples are analyzed for levels of specific enzymes in the blood stream and there are generally 5 – 6 specific things that are checked. Collectively these tests are called a “Liver Function Test”. It is proven that different diseases of the liver will cause Differing types of damage and affect liver function tests accordingly. These tests are helpful, but they do not tell the whole story. They are also useful for monitoring someone with liver disease, but are not always accurate.

A typical liver function test

Each laboratory provides a patient with a“reference range”. This is the average reading that is marked a ‘normal’ reading for the majority of the population. The normal values for liver function tests will vary between men and women, at different times of the day and will change as you get older.

Different laboratories may have slightly Differing reference ranges.

Result Unit Reference

• AP (Alkaline Phosphatase) U/L (30 to 120)
• GGT (Gamma GT) U/L (5 to 35)
• LD Lactate Dehydrogenase U/L (100-225)
• AST (Aspartate aminotransferase) U/L (5 to 45)
• ALT (Alanine aminotransferase) U/L (5 to 45)
• Albumin g/L (38-55)
• Clotting Studies (Prothrombin Time) Seconds (11 to 13.5)
• Total Bilirubin - Normal range is 3 - 18 umol/L (0.174 - 1.04mg/dL)