We use cookies to help us improve the website and your experience using it. You may delete and block all cookies from this site at any time. However, please note this may result in parts of the site no longer working correctly. If you continue without changing your settings we will assume you are happy to receive all cookies on this site.


Alpha-1-Antitrypsin; A1AT

Pseudonyms: Alpha 1 antiproteinase; A1PI.

General information

Collection container (blood):

Adults - serum (with gel separator, 4.9mL Sarstedt brown top).

Paediatrics - lithium heparin plasma (1.2mL Sarstedt orange top tube).

Collection container (faeces):

Adults - plain universal container, minimum 5g

Paediatrics - plain universal container, minimum 5g

Specimen transport/special precautions: N/A

Laboratory information

Method principle: Immunoturbidimetry

Biological reference ranges:

Blood 0.9 - 2.0 g/L
Faeces 0.13 - 2.8 mg A1AT per g faeces (wet weight)

Turnaround times:


A1AT Concentration - The test is analysed as a batch so results should be available within 1 working week.

A1AT Phenotype - This test is referred to a third party laboratory. Results may take up to 4 weeks to return.


This test is referred to third party laboratory. Results may take up to 4 weeks to return.

Clinical information

In paediatrics measurement of blood levels of A1AT is used to exclude inherited forms of alpha 1 antitrypsin deficiency. Although this is mainly in infants and children, this reason for the test may apply to patients at any age. Samples with levels below 1.2g/L have an electrophoretic phenotype test added automatically. An A1AT deficiency allele (S, Z or Null) is extremely unlikely when blood [A1AT] is >1.2g/L Genotyping is usually not required except in specific family studies requested by a clinical geneticist.

In older patients an alpha-1 antitrypsin (A1AT) level may be requested to help diagnose the cause of early emphysema, especially when a person does not have obvious risk factors such as smoking or exposure to lung irritants such as dust and fumes or there is a family history of early emphysema.

A1AT may be measured in faeces if there is suspicion of a protein-losing enteropathy. The test is indicated if the patient is clinically euvolaemic and has persistent low plasma albumin and whose urine is negative for protein/albumin on dipstick.

Factors known to significantly affect the results: A1AT is a positive acute-phase reactant whose blood levels rise in response to acute inflammation

Further information:

(Last reviewed 16th December 2016)