Alpha-1 Antitrypsin Lab Test Guide

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The alpha-1 antitrypsin is a blood test performed to measure how much alpha-1 antitrypsin is in the patient’s blood. This test is performed for a number of reasons, but most often to determine what the cause of liver dysfunction or early onset emphysema is. This test is also referred to as the AAT test or A1AT test.

How this Test is Used

This test is primarily used to assist in determining the cause of early onset emphysema, specifically when the patient does not have obvious risk factors, such as exposure to lung irritants like fumes and dust, or smoking. The cause of persistent jaundice or other signs indicating liver dysfunction may also be diagnosed with this test. In most cases, this test is performed on young children and infants, but in some cases, it is done in patients of all ages. DNA testing may be performed to follow-up on this test to determine which SERPINA 1 gene alleles are existing.

When is it Ordered?

The alpha-1 antitrypsin test for a variety of reasons, such as when an infant or newborn has jaundice persisting for longer than a week, ascites, pruritus, an enlarged spleen, or other liver injury signs.

When a patient less than 40 years of age presents with bronchitis or a chronic cough, wheezing, experiences shortness of breath after being exerted and/or other signs and symptoms of emphysema. This is particularly true when the patient has not has exposure to any things known to irritate the lungs, is not a smoker, and when any lung damaged appears to be confined in the lower lungs.

Patients who have a close family member with an alpha-1 antitrypsin deficiency may also be recommended for this blood test.

Preparation and Procedure

For most patients, no preparation is needed. If an individual patient does need to do something to prepare, their doctor will let them know and will provide adequate instructions.

This test may cause minor discomfort, but most patients do not experience any pain.

Young children or infants can have their blood sample obtained through the use of a lancet. This will puncture the skin to make it bleed enough to collect a blood sample that will collect onto a test strip or slide, or into a pipette (small glass tube).

Older children and adults will have their blood sample obtained through venipuncture. A needle is inserted into the vein and the blood collects into a special vial.

What do the Results Mean?

If the results of this blood test are considered normal, the patient’s doctor will discuss if any further testing needs to be performed. If A1AT levels are lower than normal it may indicate:

  • Cirrhosis
  • Liver tumors
  • Portal hypertension
  • Emphysema
  • Obstructive jaundice


Lab Tests Online. (2010). Alpha-1 Antitrypsin. Retrieved on September 8, 2010 from Lab Tests Online:

MedlinePlus. (2010). Alpha-1 Antitrypsin Test. Retrieved on September 8, 2010 from MedlinePlus: