ALPHA-1-ANTITRYPSIN - serum

---

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: 1.7-3.4 g/L (method dependent).

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

Interpretation: a1-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 a1-antitrypsin are increased in an acute phase response and this may mask a deficiency state; if there is a high clinical suspicion of a1-antitrypsin deficiency, phenotyping should be performed, regardless of the a1-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 distinguishes 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.

---