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Leucine aminopeptidase - urine

Definition

This is a test that measures the amount of leucine aminopeptidase (LAP) in urine.

Alternative Names

How the Test is Performed

A 24-hour urine sample is needed. The health care provider will instruct you, if necessary, to discontinue drugs that may interfere with the test (see special considerations).

• On day 1, urinate into the toilet upon arising in the morning.
• Collect all subsequent urine (in a special container) for the next 24 hours.
• On day 2, urinate into the container in the morning upon arising.
• Cap the container. Keep it in the refrigerator or a cool place during the collection period. Label the container with your name, the date, the time of completion, and return it as instructed.

For an infant, thoroughly wash the area around the urethra. Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on your infant. For boys, the entire penis can be placed in the bag and the adhesive attached to the skin. For girls, the bag is placed over the labia. Place a diaper over the infant (bag and all).

The infant should be checked frequently and the bag changed after the infant has urinated into the bag. For active infants, this procedure may take a couple of attempts -- lively infants can displace the bag. The urine is drained into the container for transport to the laboratory.

Deliver it to the laboratory or your health care provider as soon as possible upon completion.

How to Prepare for the Test

No special preparation is necessary for this test, but if the collection is being taken from an infant, a couple of extra collection bags may be necessary.

How the Test Will Feel

The test involves only normal urination, and there is no discomfort.

Why the Test is Performed

Unlike other liver enzymes, LAP can be measured in the urine. This test may be appropriate in some cases as a screening test or to avoid the risks of having blood drawn. This test is performed much less commonly than the LAP blood test (leucine aminopeptidase - serum).

LAP is a proteolytic enzyme that breaks chemical bonds in proteins at specific sites next to leucine amino acids. Serum (blood) LAP is measured to diagnose liver dysfunction. However, LAP is made by virtually all tissues. Elevations are also seen in several cancers and systemic lupus erythematosus (SLE).

Normal Results

Normal values range from 2-18 units per 24 hours.

What Abnormal Results Mean

Elevated levels of LAP can be seen in several conditions:

• Cholestasis
• Cirrhosis
• Hepatic (liver) ischemia (blood deficiency)
• Hepatic necrosis (tissue death)
• Hepatic tumor
• Hepatitis
• Breast cancer
• Endometrial cancer
• Ovarian cancer
• Germ cell tumors of the ovary and testis
• Systemic lupus erythematosus

Risks

There is essentially no risk.

Considerations

Drugs that can affect LAP measurements include estrogens and progesterones (see Progestins - oral).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.