The GGTP [gamma-glutamyl transferase] blood test is used to detect certain types of liver and bone disease. It helps to determine the cause behind elevated levels of ALP [alkaline phosphatase] that may be present. GGTP and ALP are both elevated with some liver diseases and in bile duct disease. If there is a bone disease present, then only ALP will be present. This means a positive ALP result, but a normal GGTP result, will indicate the presence of bone disease.
High levels of GGTP and ALP may not necessarily indicate the presence of disease. If a bile duct is blocked for some reason, this will cause a positive blood test. In basic terms, it can measure the presence of damage within the liver. Other tests are ordered to follow-up a positive result to determine what the specific cause of damage may be.
GGTP is also elevated in 3 out of 4 heavy alcohol drinkers. If hepatitis caused by alcohol is present or someone is receiving treatment for a severe alcoholic habit, the GGTP blood test may be ordered to track health results over time.
When Is the GGTP Blood Test Ordered?
Most of the time, this blood test will be ordered to determine if high ALP levels are because of a bone disease or because of a liver disease. It may also be ordered as part of a routine panel of screenings to determine bone and liver health even though no symptoms may be present. Anyone who is suffering from weakness, jaundice, dark urine, constant itching, and nausea with abdominal swelling should speak to their doctor right away because there may be liver damage present.
Liver damage that would result in a positive GGTP blood test may also be as a result of the following conditions.
- Congestive heart failure.
Anything that is toxic to the liver, however, will cause high GGTP levels. Someone taking the maximum recommended dose of Tylenol over a period of time, for example, may have similar GGTP results as someone who is a chronic drinker. Someone suffering from hypertension, however, may also have elevated results with no other conditions present.
Those who have increased GGTP levels also have an increased risk of suffering from heart disease. There is also an increased risk of dying because of heart disease. The link between these two events is not known.
How To Prepare For the GGTP Blood Test
It is important to avoid all alcoholic products before the GGTP blood test. Any alcohol, even in small amounts, can cause an increase in GGTP that will create a false positive. This means avoiding mouthwash, cough medication, and other products that may contain alcohol that are regularly used.
Smoking is also known to create a false positive result. Smokers who need to have this blood test should attempt to refrain from smoking for as long as they can before the test.
A number of medications can also result in a false positive on the GGTP blood test. The most common drugs are NSAIDs, but histamine receptor blockers that stop excess stomach acid production, antidepressants, and antifungal medications can also affect the results. Older women have naturally higher levels of GGTP when compared to younger women.
GGTP Levels Can Fluctuate Quite a Bit
Although a positive result from the GGTP blood test may be concerning, it is important to remember that your GGTP is very sensitive and can increase even when there are no symptoms present. Just having a glass of wine within 24 hours of the test can skew the results. Even certain dishes can change GGTP levels temporarily. For this reason, a second follow-up test may be ordered if there is a higher than expected result to rule out a false positive.
People who have consumed alcohol chronically but have stopped may still have higher than normal GGTP levels as well. It can take 30+ days for GGTP levels to return to pre-drinking levels. Continuing to eat healthy foods and avoiding alcohol can help the liver begin to heal and have functions improve over time.
The GGTP blood test is often part of a liver panel. It is commonly ordered to screen for good health, but may also be ordered if specific symptoms are being experienced. If you receive a high result, then speak with your doctor immediately to determine what your options may be.