Alpha-1 Antitrypsin (A1AT, AAT)

This is a test to diagnose the cause of early onset emphysema and/or liver problems. It also helps determine the risk of developing alpha-1 antitrypsin-related emphysema and/or liver disease in infants and children who may inherit this risk. This is a test that is often done when there are signs of liver disease as an infant or young child, when you develop emphysema (a disease that damages the lungs) before age 40, or when you have a close relative with alpha-1 antitrypsin deficiency.

Alpha-1 antitrypsin deficiency is thought to be one of the most frequent genetic deficiencies in Caucasians. In the U.S. about 1 in 2,000 have some degree of AAT deficiency.


No preparation or fasting is necessary unless you have been informed otherwise. A blood sample is obtained by inserting a needle into a vein in the arm.


  • Adults 18 to 60 years of age (M-phenotype): 78-200 mg/dL (0.78-2.00 g/L)

  • Adults > age 60: 115-200 mg/dL (1.15-2.00 g/L)

  • Neonate: 145-270 mg/dL (1.45-2.70 g/L

Ranges for normal findings may vary among different laboratories and hospitals. You should always check with your doctor after having lab work or other tests done to discuss the meaning of your test results and whether your values are considered within normal limits.


Your caregiver will go over the test results with you and discuss the importance and meaning of your results, as well as treatment options and the need for additional tests if necessary.


It is your responsibility to obtain your test results. Ask the lab or department performing the test when and how you will get your results.