ALT (Alanine Aminotransferase)

What ALT Measures

ALT is an aminotransferase, part of a family of enzymes that move amino groups between molecules. ALT's specific job is transferring an amino group from alanine to alpha-ketoglutarate, producing glutamate and pyruvate.^[1] Most of the body's ALT sits inside liver cells. ALT activity in those cells runs about 3,000 times higher than in blood.^[1] That gap is what makes the test work. When liver cells lose membrane integrity, the enzyme spills into circulation, and a blood test picks up the rise.^[1]

Its sibling enzyme AST gets released the same way, but AST also lives in heart, skeletal muscle, kidney, brain, and blood cells. ALT is largely confined to the liver, which makes it the more liver-specific of the two.^[2] The AST entry covers that broader tissue story.

How It's Measured

ALT is measured from a standard blood draw and reported in units per liter (U/L). It usually arrives as one line on a liver panel or a comprehensive metabolic panel rather than as a stand-alone order.^[3] Older reports may call it SGPT, short for serum glutamic-pyruvic transaminase. That's a legacy name for the same enzyme and the same test.^[3] As with any lab value, your lab prints its own reference interval with the result, and intervals vary by lab and method.

Why People Track ALT

ALT comes back on almost any routine blood panel, so if you're keeping your lab history in one place, you already have ALT results to file. Tracking it over time turns scattered one-off numbers into a series you can actually look at, with each draw dated and in context.

Population research also shows ALT isn't a static number. In a large study of first-time blood donors, serum ALT was independently related to body mass index.^[4] Levels also run higher in men than in women at the population level.^[1] Those are group-level patterns, not a way to read your own result. Interpreting an individual ALT value is your clinician's job.

How Go Go Gaia Tracks ALT

Go Go Gaia doesn't draw blood or run lab work. You upload an ALT result from blood work you've already had done, and the app stores it as a dated data point labeled ALT (SGPT). From there, it's charted over time next to your other lab results and tracked health data, so each new panel lands in one timeline instead of a folder of PDFs.

What the Research Shows

The concentration gap is the core fact about ALT as a lab test. ALT activity inside liver cells is roughly 3,000 times higher than in serum, which is why cell stress shows up as a measurable rise in blood.^[1]

ALT and AST are both released into circulation when liver cells are injured, but ALT's narrower tissue distribution makes it the more specific marker of the two for the liver itself.^[2]

In a 2002 study of first-time blood donors published in Annals of Internal Medicine, serum ALT activity was independently related to body mass index and to lab markers of lipid and carbohydrate metabolism, and the healthy distribution differed between men and women.^[4]

Related Terms

Frequently Asked Questions

Educational information based on published sources. Not medical advice. For personal concerns, please consult your doctor.

What does SGPT mean on my lab report?

SGPT stands for serum glutamic-pyruvic transaminase. It's the older name for the same enzyme and the same test. Labs and apps that still print SGPT next to ALT are describing one measurement, not two.

What's the difference between ALT and AST?

Both are aminotransferase enzymes that appear in blood when liver cells are injured. ALT sits mostly in the liver, which makes it the more liver-specific of the two. AST also shows up in heart, skeletal muscle, kidney, brain, and blood cells, so its level reflects more tissues than the liver alone.

Does Go Go Gaia run ALT blood tests?

No. Go Go Gaia doesn't draw blood or run labs. You get an ALT result from blood work ordered through a clinician or lab service, then upload it to your Go Go Gaia account so it's stored and charted alongside your other tracked data.