Biochemistry Test

Alpha1-proteinase inhibitor

Dr. Simi Paknikar
Medically Reviewed by Dr. Simi Paknikar, MD
Last Updated on Mar 28, 2014
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Test : Alpha1-proteinase inhibitor

Indications : Alpha1-Proteinase Inhibitor test is a laboratory test that is carried out to measure the amount of A1AT enzyme in your blood.

This test is useful in diagnosing A1AT deficiency that causes a rare form of emphysema in adults and a rare form of cirrhosis in both children and adults. A1AT deficiency causes the liver and the lung to be exposed to the damaging effects of the proteases. This condition is hereditary and is likely to pass through families.

Most of us have two copies of the A1AT gene. However, some individuals with sub optimal levels of the enzyme have one normal and one abnormal gene, while those with the severe form of the disease have two abnormal copies of the gene.

The blood sample for the test is usually acquired by puncturing a vein in the forearm. This procedure involves very little risk.

Physiology : Alpha-1 proteinase, also known as Alpha-1 Anti-Trypsin (A1AT), is an enzyme that functions as an inhibitor of a variety of proteins cleaving enzymes (proteases) such as elastase, trypsin and chymotrypsin. In other words, this A1AT protects the liver and the lungs from the damaging effects of certain harmful enzymes.

A1AT deficiency is an inherited disorder which impacts both adults and children. In normal individuals the liver produces adequate quantity of AAT and releases it into the blood stream; but for those with faulty genes, the enzyme is produced in inadequate measures, or not produced at all, causing lung disease (emphysema) in adults and liver disease in both adults and children.

Normal Range : 150-250mg/100ml

Interpretation : Normal value of A1AT ranges from 150-250mg/100ml. This value can vary between different laboratories.

Lower than normal levels could indicate -

Cirrhosis
Emphysema
Obstructive jaundice
Portal hypertension
Tumors in the liver

More Information

Children with A1AT deficiency are likely to develop liver problems that lasts all through their lives. The condition cannot be cured but can be treated.

One method of treatment is gene therapy which involves replacing the missing gene. This treatment is not popular world- wide and is still in its nascent stage. The other treatment option is to undergo a lung transplant.

Smoking aggravates the symptoms of AAT deficiency. Those at risk must stay away from cigarette smoke.

AAT Test

How the Test is performed

A blood sample is needed. For information on how this is done, see: Venipuncture

How to prepare for the Test

There is no special preparation.

What you will feel when the Test is performed

When the needle is inserted to draw blood, you may feel moderate pain, or only a prick with an accompanying slight stinging sensation. Afterward, there may be some throbbing.

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