Type of test Blood
 Normal findings
 Male and female age 45 years and older: 8-38 units/L or 8-38 international units/L (SI units)
 Female younger than age 45 years: 5-27 units/L or 5-27 inter national units/L (SI units)
 Elderly: slightly higher than adult level
Child: similar to adult level
Newborn: five times higher than adult level
Test explanation and related physiology
This test is used to detect liver cell dysfunction, and it very accurately indicates even the slightest degree of cholestasis. This is the most sensitive liver enzyme in detecting biliary obstruction, cholangitis, or cholecystitis. As with leucine aminopeptidase and 5-nucleotidase (pp. 566 and 652), the elevation of GGTP generally parallels that of alkaline phosphatase; however, GGTP is more sensitive. GGTP is not increased in bone diseases as is alkaline phosphatase. A normal GGTP level with an elevated alkaline phosphatase level implies skeletal disease. Elevated GGTP and alkaline phosphatase levels imply hepatobiliary disease. Another important clinical aspect of GGTP is that it can detect chronic alcohol ingestion. Therefore it is very useful in the screening and evaluation of patients with alcoholism. GGTP is elevated in approximately 75% of patients who chronically drink alcohol.
Why this enzyme is elevated after an acute myocardial infarction is not clear. It may represent the associated hepatic insult (if elevation occurs in the first 7 days) or the proliferation of capillary endothelial cells in the granulation tissue that replaces the infarcted myocardium. The elevation usually occurs 1 to 2 weeks after infarction.
Interfering factors
 • Values may be decreased in late pregnancy.
* Drugs that may cause increased GGTP levels include alcohol, phenobarbital, and phenytoin.
* Drugs that may cause decreased levels include clofibrate and oral contraceptives.
Procedure and patient care
 • See inside front cover for Routine Blood Testing.
• Fasting: yes
• Blood tube commonly used: red
• Patients with liver dysfunction often have prolonged clotting times.
Abnormal findings
 Increased levels
- Hepatitis
- Cirrhosis
- Hepatic necrosis
- Hepatic tumor or metastasis
- Hepatotoxic drugs
- Cholestasis
- Jaundice
- Myocardial infarction
- Alcohol ingestion
- Pancreatitis
- Cancer of the pancreas
- Epstein-Barr virus (infectious mononucleosis)
- Cytomegalovirus infections
- Reye syndrome