Alanine Aminotransferase (ALT)
How It Feels
The blood sample is taken from a vein in your arm. An elastic band
is wrapped around your upper arm. It may feel tight. You may feel nothing at
all from the needle, or you may feel a quick sting or pinch.
There is very little chance of a problem from having blood sample
taken from a vein.
- You may get a small bruise at the site. You can
lower the chance of bruising by keeping pressure on the site for several
- In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.
- Ongoing bleeding can be a
problem for people with bleeding disorders. Aspirin, warfarin (Coumadin), and
other blood-thinning medicines can make bleeding more likely. If you have
bleeding or clotting problems, or if you take blood-thinning medicines, tell
your doctor before your blood sample is taken.
An alanine aminotransferase (ALT) test measures the amount of this
enzyme in the blood. Results are usually available
within 12 hours.
The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.
units per liter (U/L) or 0.17–0.68 microkatals per liter (mckat/L)
7–35 U/L or 0.12–0.60 mckat/L
High levels of ALT may be caused by:
- Liver damage from conditions such as
hepatitis or cirrhosis.
- Lead poisoning.
- Exposure to carbon
- Decay of a large tumor (necrosis).
- Many medicines, such
- Growth spurts, especially in young children. Rapid growth can cause mildly elevated levels of ALT.