Leucine aminopeptidase is a protein, called an enzyme, that is normally found in liver cells. This article discusses the test to measure how much of this protein appears in your urine.

Your blood can also be checked for this protein. See also: Serum leucine aminopeptidase

A 24-hour urine sample is needed:

• On day 1, urinate into the toilet when you get up in the morning.
• Afterwards, collect all urine in a special container for the next 24 hours.
• On day 2, urinate into the container when you get up in the morning.
• 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 the 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. Diaper as usual over the secured bag.

This procedure may take a couple of attempts. The infant should be checked frequently and the bag changed after the infant has urinated into the bag. The urine is drained into the container before taking it to the laboratory.

Deliver the sample to the laboratory or your health care provider as instructed.

Your health care provider may tell you to stop taking any drugs that could affect the test. Drugs that can affect the results of this test include estrogen and progesterone. Never stop taking any medicine without first talking to your doctor.

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

Your doctor may order this test to see if your liver is damaged. It may also be done to check for certain cancers and systemic lupus erythematosus (SLE).

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

Note: Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

Increased levels of leucine aminopeptidase can be seen in several conditions:

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

There is essentially no risk.

McPherson RA, Pincus MR. Henry's Clinical Diagnosis and Management by Laboratory Methods. 21st ed. St. Louis, Mo: WB Saunders; 2006.