GGT, glucose and coagulation testing

The liver is responsible for production of coagulation factors. The international normalized ratio (INR) measures the speed of a particular pathway of coagulation, comparing it to normal speeds. If the INR is increased, it means it is taking longer than usual for blood to clot. The INR will only be increased if the liver is so badly damaged that synthesis of vitamin K-dependent coagulation factors has been impaired - it is not a sensitive measure of liver function. It is very important to normalize the INR before operating on people with any liver problem (usually by transfusion with blood plasma containing the deficient factors) as they could bleed excessively.

The GGT test helps to detect liver disease and bile duct injury. Doctors can also use the test to help find out the reason for a raised level of alkaline phosphatase (ALP). Both ALP and GGT are elevated in disease of the bile ducts and in some liver diseases, but only ALP will be elevated in bone disease. If the GGT level is normal in a person with a high ALP, then the cause is most likely to be bone disease. GGT can also be used to screen for alcohol abuse also as it will be elevated in about 75% of long-term drinkers.

A doctor usually requests GGT along with other tests to evaluate a person who has signs or symptoms that suggest some liver disease. Some of the symptoms of liver injury include jaundice, nausea, vomiting, abdominal (around the stomach area) swelling, abdominal pain, and tiredness. GGT is increased in most diseases that cause damage to the liver or bile ducts, but is usually not helpful in distinguishing between different causes of liver damage. GGT is also useful in determining the cause of a high ALP. In people with a history of alcohol abuse who are undergoing treatment, GGT may be used to check that the person is following the treatment program properly.

Raised GGT levels indicate that something is going on with your liver but not specifically what. In general, the higher the level the greater the damage to your liver. Elevated levels may be due to liver disease, but they may also be due to congestive heart failure, drinking alcohol, and use of many prescription and non-prescription drugs including nonsteroidal anti-inflammatory drugs (NSAIDs), lipid-lowering drugs, histamine blockers (used to treat excess stomach acid production), antifungal agents, anticonvulsants (seizure control medications), antidepressants, and hormones such as testosterone. Oral contraceptives (birth control pills) and clofibrate can decrease GGT levels.

Even very small amounts of alcohol within 24 hours of your GGT test may cause a temporary increase in the GGT. If this occurs, your doctor may want to repeat the test to verify that it is normal. GGT levels fall after meals, so it is best to be tested when you have not eaten for at least 8 hours. Several drugs increase (induce) the concentration of GGT in the blood. Please note that the increases do not indicate damage to the liver and can be considered an interference.

Glucose is a simple sugar that serves as the main source of energy for the body. The carbohydrates we eat are broken down into glucose, absorbed by the small intestine, and circulated throughout the body. Most of the body’s cells require glucose for energy production; brain and nervous system cells not only rely on glucose for energy, they can only function when glucose levels in the blood remain above certain levels.

Severe, acute hyperglycemia or hypoglycemia can be life-threatening, causing organ failure, brain damage, coma, and, in extreme cases, death. Chronically high blood glucose levels can cause progressive damage to body organs such as the kidneys, eyes, heart and blood vessels, and nerves. Chronic hypoglycemia can lead to brain and nerve damage.
Some women may develop hyperglycemia during pregnancy and this may lead to gestational diabetes. If untreated, this can cause these mothers to give birth to large babies who may have low glucose levels. Women who have had gestational diabetes may or may not go on to develop diabetes.