Blood Test: Alanine Aminotransferase (ALT, or SGPT)





What It Is



An alanine aminotransferase (ALT) test is often part of an initial screening for liver disease.

The liver plays several important roles: It stores fuel from food,
makes proteins, and helps remove toxins from the body. The liver also
makes bile, a fluid that helps in digestion. Proteins called enzymes
help the liver build and break down proteins. ALT (or SGPT, which stands
for serum glutamic-pyruvic transaminase) is one of these enzymes. It's
found in particularly large amounts in the liver and plays an important
role in metabolism, the process that converts food into energy.

Normally, ALT is found inside liver cells. But if the liver is
inflamed or injured, ALT is released into the bloodstream. Measuring
blood levels of ALT can give doctors important information about how
well the liver is functioning and whether a disease, drug, or other
problem is affecting it.

Why It's Done



The ALT test may be ordered if your child is experiencing symptoms of
liver disease, including jaundice (yellowish skin or eyes), dark urine,
nausea, vomiting, or abdominal pain. It also might be ordered to help
diagnose infections of the liver such as viral hepatitis (ALT levels are
high with acute hepatitis) or to monitor patients taking medications
that cause liver-related side effects.

The ALT test is often performed as part of a full hepatic function
panel that includes other liver enzyme tests. Looking at ALT levels
along with those of other liver enzymes — such as aspartate
aminotransferase (AST) and alkaline phosphatase (ALP) — can give doctors
more specific information about liver problems.

Preparation



No special preparations are needed for this test. You should tell
your doctor about any medications your child is taking because certain
drugs might alter the test results.

On the day of the test, having your child wear a short-sleeve shirt
can make things faster and easier for the technician who will be drawing
the blood.The Procedure



A health professional will usually draw the blood from a vein. For an
infant, the blood may be obtained by puncturing the heel with a small
needle (lancet). If the blood is being drawn from a vein, the skin
surface is cleaned with antiseptic, and an elastic band (tourniquet) is
placed around the upper arm to apply pressure and cause the veins to
swell with blood. A needle is inserted into a vein (usually in the arm
inside of the elbow or on the back of the hand) and blood is withdrawn
and collected in a vial or syringe.

After the procedure, the elastic band is removed. Once the blood has
been collected, the needle is removed and the area is covered with
cotton or a bandage to stop the bleeding. Collecting blood for this test
will only take a few minutes.




What to Expect



Either method (heel or vein withdrawal) of collecting a sample of
blood is only temporarily uncomfortable and can feel like a quick
pinprick. Afterward, there may be some mild bruising, which should go
away in a few days.

Getting the Results



The blood sample will be processed by a machine. The results are usually reported after a few hours or the next day.

If the results seem to point to liver damage or disease, further
testing may be necessary to determine what's causing the problem and how
to treat it.

Risks



The ALT test is considered a safe procedure. However, as with many
medical tests, some problems can occur with having blood drawn, such as:

• fainting or feeling lightheaded
  
• hematoma (blood accumulating under the skin causing a lump or bruise)
  
• pain associated with multiple punctures to locate a vein
  

Helping Your Child



Having a blood test is relatively painless. Still, many kids are
afraid of needles. Explaining the test in terms your child can
understand might help ease some of the fear.

Allow your child to ask the technician any questions he or she might
have. Tell your child to try to relax and stay still during the
procedure, as tensing muscles and moving can make it harder and more
painful to draw blood. It also may help if your child looks away when
the needle is being inserted into the skin.

If You Have Questions



If you have questions about the ALT test, speak with your doctor.