Alpha-1-antitrypsin - serum

Last updated: Wednesday, 07, April, 2004

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Item Process
Specimen

5 mL blood in plain tube.

5 mL blood in lithium heparin tube for genotyping, if indicated.

Method

Immunoassay; IEF for phenotyping.

Reference Interval

0.9-1.7 g/L (method dependent).

Application

Detection of hereditary deficiency. Investigation of early onset emphysema; neonatal hepatitis; juvenile cirrhosis; panniculitis.

Interpretation

α1-antitrypsin deficiency is associated with early onset emphysema, hepatitis and cirrhosis and with panniculitis. If deficiency is documented, phenotyping should be done on proband and family. Levels of α1-antitrypsin are increased in an acute phase response and this may mask a deficiency state; if there is a high clinical suspicion of α1-antitrypsin deficiency, phenotyping should be performed, regardless of the α1-antitrypsin level.

Genetic variants with at least 100 alleles have been described; genotyping is currently available for two phenotypes associated with disease: S and Z.
Genotyping is currently not the preferred first test but may be used to distinguish ZZ from Z null or SS from S null patients without the need for family studies.

Reference

Perlmutter DH. Gastroenterol Clin N Amer 1995; 24: 27-43.