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SGPT / ALT Test (Liver Enzyme)

SGPT (also called ALT) is the most important liver enzyme in your blood test. A raised SGPT is often the first sign of liver damage. Here's what your number means.

Written and clinically reviewed by Suman Konda, PharmD, Clinical Pharmacist · Based on peer-reviewed sources · Editorial policy · Not medical advice

Last reviewed and updated: · How we check our content

What is SGPT / ALT?

SGPT stands for Serum Glutamic Pyruvic Transaminase. Its modern name is ALT (Alanine Aminotransferase). It is an enzyme found mainly in liver cells. When liver cells are damaged or inflamed, they release SGPT into the bloodstream: causing blood levels to rise. SGPT is the most liver-specific enzyme: a raised SGPT almost always means the liver is involved.

SGPT Normal Range

GroupNormal Range (U/L)
Men7 – 56 U/L
Women7 – 45 U/L
Children7 – 45 U/L
Mild elevation1–3× upper limit
Moderate elevation3–10× upper limit
Severe elevation>10× upper limit

Why “Normal” ALT Is Set Higher Than It Should Be

The reference range your laboratory prints was not handed down from first principles. It was derived by measuring ALT in a group of apparently healthy people and taking the middle 95%. The problem is what counted as healthy. The thresholds in common use were established in the 1980s, from reference populations that would have contained a substantial number of people with undiagnosed hepatitis C and fatty liver disease — conditions that raise ALT.2

Building a “normal” range from a group that included liver disease sets the ceiling too high. The consequence is that a meaningful number of people whose ALT falls inside the quoted range have ongoing liver inflammation and scarring, and are at risk of progression, while being told their liver tests are fine.2

Men and Women Do Not Share a Healthy Range

When researchers rebuild the range from a genuinely screened population — excluding viral hepatitis, fatty liver, raised BMI, blood pressure and lipids — two things emerge. The healthy values sit much lower than the printed range, and they differ markedly by sex.

In one such study of 6,677 adults, the median ALT among healthy participants was 18 U/L in men and 13 U/L in women. The upper limit derived from that healthy group was 40 U/L for men but only 28 U/L for women.3 Many laboratories still report a single range for both.

What this means for a woman with an ALT of 35Reported against a combined range topping out near 40, that result is filed as normal. Measured against a range derived from healthy women, it sits above the limit. It does not diagnose anything on its own, but it is a reason to look at the usual drivers — weight, alcohol, medicines, viral hepatitis — rather than to stop asking.

The factors that pushed ALT up in that study are the ones worth acting on: being overweight, raised triglycerides and cholesterol, higher blood pressure, and fatty liver.3 These cluster together, and ALT is often the first of them to appear on a blood test.

One further caution. ALT reports liver cell damage, not liver function. In advanced cirrhosis, when few working liver cells remain to leak the enzyme, ALT can fall back into the normal range while the liver is failing. A normal ALT is reassuring in someone otherwise well; it is not reassuring on its own in someone with known liver disease.

What does HIGH SGPT mean?

HIGH SGPT mildly elevated (1–3× normal)

Mild elevation is extremely common and often caused by: fatty liver disease (NAFLD, the most common cause), alcohol consumption, obesity, Type 2 diabetes, certain medications (statins, paracetamol, antibiotics), vigorous exercise before the test, or thyroid disease. A single mildly elevated SGPT without symptoms usually warrants a repeat test in 4–6 weeks before any action.

HIGH SGPT moderately elevated (3–10× normal)

Moderate elevation suggests more significant liver injury. Causes include: acute viral hepatitis (Hepatitis A, B, E), alcoholic hepatitis, drug-induced liver injury (DILI), or autoimmune hepatitis. Requires further investigation: Hepatitis B surface antigen, Hepatitis C antibody, ultrasound abdomen.

HIGH SGPT severely elevated (>10× normal)

Severe elevation is a liver emergency. Causes: acute viral hepatitis, paracetamol (acetaminophen) overdose, ischaemic hepatitis (shock liver), or severe drug reaction. Seek immediate medical attention if SGPT is more than 10 times the upper limit of normal.

SGPT vs SGOT: what's the difference?

SGPT is more liver-specific than SGOT

SGOT (AST) is found in the liver, heart, muscles and kidneys. SGPT (ALT) is almost exclusively in the liver. So a raised SGPT with normal SGOT points strongly to liver disease. A raised SGOT with normal or mildly raised SGPT may suggest heart attack, muscle damage or alcohol-related liver disease. The SGOT:SGPT ratio (De Ritis ratio) >2 suggests alcoholic liver disease.

Questions to ask your doctor

  • Is my SGPT rise from fatty liver, medication or a virus?
  • Should I test for Hepatitis B and C?
  • Do I need a liver ultrasound?
  • Which medications should I stop or reduce?

Frequently asked questions

Why does my lab's SGPT / ALT range differ from the one shown here?
Every laboratory sets its own reference interval from the analyser, reagents and reference population it uses, so two labs can publish different SGPT / ALT intervals and both be correct, even reporting in the same U/L. Read your result against the range printed on your own report.
Is a slightly abnormal SGPT / ALT a reason to worry?
Rarely on its own. Reference intervals are built to contain the middle 95% of a healthy population, so mild deviations are common in well people. The size of the deviation, its direction over time and your symptoms decide whether it means anything.
How soon should SGPT / ALT be rechecked after an abnormal result?
It depends on how abnormal the value was and why it was ordered, from days for a markedly abnormal result to months for routine monitoring. If no interval was given, that is worth asking rather than assuming.

References

The clinical information on this page is drawn from peer-reviewed sources indexed by the US National Library of Medicine. Links go to the source so you can read it yourself.

  1. Liver Function Tests. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK482489
  2. Liver Toxicity. In: StatPearls. Treasure Island (FL): StatPearls Publishing. NCBI Bookshelf NBK526106
  3. Pacifico L, Ferraro F, Bonci E, Anania C, Romaggioli S, Chiesa C. Upper limit of normal for alanine aminotransferase: quo vadis? Clin Chim Acta. 2013;422:29–39. PMID 23566931 · doi:10.1016/j.cca.2013.03.030
  4. Huong NTC, Karimzadeh S, Thanh NT, et al. Updated upper limit of normal for serum alanine aminotransferase value in Vietnamese population. BMJ Open Gastroenterol. 2022;9(1):e000870. PMID 35613736 · doi:10.1136/bmjgast-2022-000870

Related reading

Medical Disclaimer: This page is for general educational purposes only. It does not constitute medical advice. Always consult a qualified doctor before making any health decisions.