ALT and AST Liver Enzymes Explained
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ALT and AST (liver enzymes)

Also called ALT, AST, SGPT, SGOT, liver enzymes, alanine aminotransferase, aspartate aminotransferase · Reviewed

Definition: ALT (alanine transaminase) and AST (aspartate aminotransferase) are enzymes that are normally low in the blood. When liver cells are damaged, they release these enzymes, so high levels can be a sign of liver injury. Both are usually measured together as part of a group of liver function tests.

How the two differ

MedlinePlus says ALT is found mainly in the liver, so it checks more specifically for liver damage. AST is found in the liver but also in the heart, muscles and other tissues. That means a high AST can come from places other than the liver.

MedlinePlus also says the amount of ALT in the blood is not related to how much the liver may be damaged.

Why it shows up on labs when you track doses

The Depo-Testosterone label says long-term high doses of androgens, mainly the 17-alpha alkyl androgens, have been linked to liver tumors and peliosis hepatis, which can be life-threatening. The Xyosted label says long-term intramuscular testosterone enanthate has produced multiple liver adenomas, that Xyosted is not known to do this, and to report signs such as jaundice.

MedlinePlus lists taking medicines that can harm the liver as one reason to check ALT.

Common mix-ups

  • Hard exercise. MedlinePlus says intense exercise can affect ALT, and that exercise can affect AST. A heavy session before a draw is worth mentioning.
  • Fasting. These tests are often ordered with others that need fasting; MedlinePlus says up to 12 hours for AST panels.
  • Old names. ALT may appear as SGPT and AST as SGOT on some reports.

Each lab sets its own reference range, so read your result against the range printed on your own report, and talk with your clinician about what it means for you.

Read more on Dose Track: Testosterone enanthate guide · Logging lab results in Dose Track

General education drawn from labels and published studies, not personal medical advice. Your prescriber, pharmacist and the label that came with your product are the final word.
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Frequently asked questions

Can working out raise liver enzymes?+
MedlinePlus says intense exercise can affect ALT, and AST is also found in muscle. Tell your provider about hard training before the draw.
What is the difference between ALT and AST?+
ALT is mostly in the liver, so it is more specific to liver damage. AST is also in the heart and muscles, so it can rise for other reasons.

Sources

  1. MedlinePlus (NIH): ALT Blood Test
  2. MedlinePlus (NIH): AST Test
  3. MedlinePlus (NIH): Liver Function Tests
  4. Depo-Testosterone (testosterone cypionate) US prescribing information, DailyMed
  5. Xyosted (testosterone enanthate) US prescribing information, sections 1, 5 and 12.3, DailyMed

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