ALT
Also reported as: Alanine aminotransferase · SGPT
An enzyme concentrated in liver cells, released into blood when they are stressed or damaged.
Traditional ceilings of 40–55 U/L; updated thresholds put the true upper limit closer to 30 for men and 20 for women.
Revised healthy-population thresholds place the upper limit at about 30 U/L for men and 19–20 U/L for women.
Check your result
Enter the number from your report. Nothing is sent anywhere — this runs in your browser.
Where the thresholds sit
| Band | Range (U/L) | Note |
|---|---|---|
| Optimal | < 25 | — |
| Borderline | 25–40 | — |
| Elevated | 40–100 | — |
| Markedly elevated | > 100 | Needs medical assessment. |
Why it matters
The most specific routine marker of liver cell injury, and in practice the commonest reason it is raised is fatty liver — which now affects roughly a quarter of adults and is tightly bound up with insulin resistance. Conventional upper limits were set from populations that already included a great many people with undiagnosed fatty liver, so the 'normal' ceiling is too generous.
What raises it
- Fatty liver disease
- Alcohol
- Intense exercise in the preceding days — muscle contains some ALT
- Medications including paracetamol, statins and some antibiotics
- Viral hepatitis
- Coeliac disease
What lowers it
- Weight loss
- Alcohol reduction
- Treating the underlying cause
How to move it
- 1Avoid hard training for 48 hours before the test — exercise alone can push ALT above the reference range.
- 2If it stays raised, fatty liver is the most likely explanation, and weight loss of 7–10% reverses it in most people.
- 3Reduce alcohol and fructose.
- 4Persistent elevation deserves proper investigation rather than watchful waiting.
What moves this marker
Interventions on this site with evidence behind them for this specific marker. None of them replaces working out why yours is where it is.
What makes a single reading misleading
- Skeletal muscle damage raises ALT, so a heavy session or rhabdomyolysis can mimic liver injury.
- A normal ALT does not exclude significant liver fibrosis — cirrhosis can present with normal enzymes.
- Sex-specific thresholds matter here more than for most markers.
Sources
Read next
Educational only. Reference ranges are not diagnostic thresholds and this page cannot account for your medical history, medication or symptoms. Discuss any result that concerns you with a qualified clinician. See our medical disclaimer.