MedlinePlus Medical Encyclopedia: Leucine aminopeptidase

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Leucine aminopeptidase - serum

Contents of this page:
Illustrations Alternative names Definition How the test is performed How to prepare for the test How the test will feel	Why the test is performed Normal Values What abnormal results mean What the risks are Special considerations

Illustrations

Blood test

Alternative names Return to top

Serum leucine aminopeptidase

Definition Return to top

This is a blood test that measures the amount of the enzyme leucine aminopeptidase (LAP).

How the test is performed Return to top

Blood is drawn from a vein, usually on the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and an elastic band is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the band to fill with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

For an infant or young child:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.

How to prepare for the test Return to top

The health care provider may advise you to discontinue drugs that can affect the test (see "Special considerations").

For infants and children:
The preparation you can provide for this test depends on your child's age and previous experiences. For specific information regarding how you can prepare your child, see the following topics:

infant test or procedure preparation (birth to 1 year)
toddler test or procedure preparation (1 to 3 years)
preschooler test or procedure preparation (3 to 6 years)
schoolage test or procedure preparation (6 to 12 years)
adolescent test or procedure preparation (12 to 18 years)

How the test will feel Return to top

When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.

Why the test is performed Return to top

LAP is an enzyme normally found in liver cells (hepatocytes). It is is also released into the blood after damage to liver cells, such as from drugs or infection (for example, hepatitis). Measurement of LAP in blood may serve as an indicator of liver damage.

LAP can also be released into blood by tumors that arise in the liver, so it may also serve as a tumor marker or indicator.Other enzymes, such as ALT, AST, ALP, LDH, and GGT, are more commonly measured for the same purpose.

Testing serum LAP is generally not as sensitive or as convenient as testing other liver enzymes to detect some liver problems. Unlike other liver enzymes, LAP can be measured in the urine (see LAP - urine).

Normal Values Return to top

male: 80 to 200 U/ml
female: 75 to 185 U/ml

Note: U/ml = units per milliliter

What abnormal results mean Return to top

cholestasis
cirrhosis
hepatic (liver) ischemia (blood deficiency)
hepatic necrosis (tissue death)
hepatic tumor
hepatitis

What the risks are Return to top

excessive bleeding
fainting or feeling light-headed
hematoma (blood accumulating under the skin)
infection (a slight risk any time the skin is broken)
multiple punctures to locate veins

Special considerations Return to top

Drugs that can affect LAP measurements include estrogens and progesterones.

Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Update Date: 9/3/2003

Updated by: Michael C. Milone, M.D., Ph.D., Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.

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