Blood Test: Aspartate Aminotransferase (AST, or SGOT)





Blood Test: Aspartate Aminotransferase (AST, or SGOT)
What It Is



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

The liver plays a variety of important roles in the body: 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. AST (or
SGOT, which stands for serum glutamic-oxaloacetic transaminase) is one
of these enzymes.

AST is found in many tissues throughout the body, including the
liver, heart, muscles, kidney, and brain. If any of these organs or
tissues is affected by disease or injury, AST is released into the
bloodstream. This means that AST isn't as specific an indicator of liver
damage as ALT (also known as alanine aminotransferase, another type of
enzyme found almost entirely in the liver).

However, when doctors look at blood levels of AST — especially in
relation to the amounts of other liver enzymes — they can get important
information about how well the liver is functioning and what type of
disease or problem might be affecting it.

Why It's Done



If your child is experiencing symptoms of liver disease — including
jaundice (yellowish skin or eyes), dark urine, nausea, vomiting, or
abdominal swelling — the AST test may be ordered. It may also be ordered
to help diagnose infections of the liver such as viral hepatitis, or to
monitor patients taking medications that can cause liver-related side
effects.

The AST test is often performed as part of a full hepatic function
panel that includes other liver enzyme tests. Looking at AST levels
along with those of other liver enzymes — such as ALT 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 within 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 AST 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 AST test, speak with your doctor.