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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:

Blood:

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.

Faeces:

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)