Gamma-Glutamyl Transferase (GGT)
GGT is strongly right-skewed and rises with age, particularly in males (men), reflecting alcohol exposure, metabolic liver disease, medication effects, and cholestatic processes across the population.
Unit: U/L · 12 slices · age and sex · 1 source
Filed under panels: Liver Function , Metabolic Panel · topics: Liver , Metabolic
Gamma-glutamyl transferase (GGT) is a liver and biliary enzyme measured on the standard chemistry panel. It is highly sensitive to alcohol exposure, metabolic dysfunction, medication effects, and cholestatic disease, which gives the population distribution a pronounced right tail. These percentiles describe the full US population rather than a screened healthy subgroup, and the per-group pages break the distribution down by sex (men and women) and age.
Population Distribution
Browse by Demographic
| Age (years) | male (U/L) | female (U/L) |
|---|---|---|
| 20-29 | 10–76.7 (21) | 7–45.5 (14) |
| 30-39 | 11.1–93.2 (25.4) | 7–44.6 (15) |
| 40-49 | 12–105.3 (26) | 7.3–57 (15) |
| 50-59 | 13–115.8 (26) | 9–74 (20) |
| 60-69 | 11.8–91.8 (24) | 9–64.9 (18) |
| 70+ | 10.1–81 (22) | 9–58.7 (17) |
Frequently Asked Questions
Why is GGT so right-skewed?
Most adults have modest GGT values, but alcohol use, steatotic liver disease, medication exposure, cholestasis, and chronic cardiometabolic disease push a smaller subgroup much higher. That creates a long upper tail.
Why is GGT usually higher in males?
At the population level, males (men) have more of the exposures that shift GGT upward, especially alcohol-related and metabolic-liver contributors, so the whole distribution tends to sit higher than in females (women).
How is GGT used with ALP?
A high ALP with a high GGT points more strongly toward a hepatobiliary source. A high ALP with a normal GGT makes a bone source more plausible.
What is a normal GGT reference range for women?
There is no single value: among US women the median GGT runs from about 14 to 20 U/L across adult age groups, with most women (the middle 90%) falling roughly between 7-9 U/L at the low end and 50-75 U/L at the upper end, which rises with age. These are population percentiles, not a clinical reference interval. See the per-age female pages for the exact range in each women's age group.