The ALT blood test, also known as alanine aminotransferase or SGPT, is one of the most important markers for understanding liver health. ALT is an enzyme stored in liver cells; when those cells are stressed or inflamed, ALT levels change.

But many people see results like ALT 8 (U/L), ALT “low”, or “mildly elevated” ALT, and don’t know what it means.

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What Is an ALT Blood Test?

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ALT (alanine aminotransferase) is an enzyme that helps your liver process amino acids. When liver cells are stressed or damaged, ALT can leak into the bloodstream.

You might also hear ALT Blood tests called: 

• SGPT test
• ALT test
• ALT blood test
• ALT series test (used when ALT is checked repeatedly over time)

You may be asked to test ALT if you notice: 

• Fatigue or low energy
• Right-upper-abdominal discomfort
• Unexplained nausea
• History of alcohol use
• Fatty liver risk factors
• High triglycerides or cholesterol
• Medication or supplement side effects
  
  

ALT Blood Test Normal Range

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Adult reference ranges can vary slightly from lab to lab. Typically, optimal ALT levels fall within the following ranges:

• Men: <55 U/L
• Women: <45 U/L

Important: A single high or low ALT is less meaningful than a series of trended results over time.

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ALT Interpretation Basics

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• Normal ALT → liver cells functioning normally
• Mild elevation → very common; often metabolic or lifestyle-related
• High ALT → inflammation or stress on liver cells
• Low ALT: Low ALT is often benign (especially in older age or lower muscle mass), but in some cases - especially when combined with other risk factors - may reflect malnutrition, deficiency (e.g. vitamin B6), or other underlying health conditions.

ALT is best interpreted alongside AST, GGT, and the AST:ALT ratio.

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So Your Results Came Back with High ALT Levels

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High ALT means your liver cells are irritated or inflamed. The most common reasons are fatty liver (NAFLD/MASLD), alcohol-related liver stress, or medication/supplement effects like Tylenol, statins, NSAIDs, antibiotics, antifungals, seizure meds, or bodybuilding supplements. Viral hepatitis can cause sharp spikes, and intense exercise in the last 2-3 days can temporarily bump ALT as well. Less commonly, autoimmune or genetic liver conditions can cause persistent elevation.

Typical retest window:
4–12 weeks, depending on underlying cause.

For alcohol-related elevations, retest may be recommended after 2-4 weeks of abstinence.

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How to Support Healthy ALT

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If your ALT comes back high; immediate actions you can take include:

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• Reduce alcohol
• Increase physical activity
• Improve metabolic health (lose visceral fat, reduce sugar intake)
• Review medications with your clinician
• Avoid unnecessary supplements
• Support liver-friendly nutrition (omega-3, antioxidants, B vitamins)
  
  

If ALT is low:

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• Check dietary vitamin B6
• Maintain or build muscle mass
• Ensure proper protein intake
• Check for chronic conditions if symptoms persist

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FAQS

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Is ALT or AST more important?

ALT is more liver-specific, but both matter. AST can rise from muscle injury.

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What is ALT in a blood test?

ALT (alanine aminotransferase) is a liver enzyme that helps your body process amino acids. It mostly lives inside liver cells, so when the liver becomes irritated or inflamed, ALT leaks into the bloodstream. This makes ALT one of the most specific markers of liver health.

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When should you worry about ALT levels?

ALT becomes more concerning when it stays elevated for >3 months, or when levels reach 5–20× normal which may indicate more significant liver injury, medication effects, or viral hepatitis.

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Is 70 a high ALT level?

Yes. ALT of 70 U/L is above normal for both men and women.

• For men, it’s typically ~1.5× the upper limit
  
• For women, it’s often ~2× the upper limit

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Conclusion

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ALT is one of the most important liver enzymes to track for overall health. Whether your ALT is high, low, or simply borderline, your results are best understood in context. Your lifestyle, medications, alcohol use, and metabolic health all influence ALT values.

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If you want clear insight into your liver enzymes without visiting a clinic, an at-home liver function test can help you monitor ALT, AST, and other markers quickly and conveniently