Davis's Lab & Diagnostic Tests

α1-Antitrypsin and α1-Antitrypsin Phenotyping

α1-Antitrypsin and α1-Antitrypsin Phenotyping is a topic covered in the Davis's Lab & Diagnostic Tests.

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α1-antitrypsin: A1AT, α1-AT, AAT; α1-antitrypsin phenotyping: A1AT phenotype, α1-AT phenotype, AAT phenotype, Pi phenotype.

Common Use:
To assist in the identification of chronic obstructive pulmonary disease (COPD) and liver disease associated with α1-antitrypsin (α1-AT) deficiency.

Serum for α1-AT and α1-AT phenotyping collected in a gold-, red-, or red/gray-top tube. Whole blood from one full lavender-top (EDTA) is also acceptable.

Normal Findings:
(Method: Rate nephelometry for α1-AT, isoelectric focusing/high-resolution electrophoresis for α1-AT phenotyping)


AgeConventional UnitsSI Units (Conventional Units × 0.01)
0–1 mo124–348 mg/dL1.24–3.48 g/L
2–6 mo111–297 mg/dL1.11–2.97 g/L
7 mo–2 yr95–251 mg/dL0.95–2.51 g/L
3–19 yr110–279 mg/dL1.1–2.79 g/L
Adult126–226 mg/dL1.26–2.26 g/L

α1-Antitrypsin Phenotyping

There are three major protease inhibitor phenotypes:

  • MM—Normal
  • SS—Intermediate; heterozygous
  • ZZ—Markedly abnormal; homozygous

The total level of measurable α1-AT varies with genotype. The effects of α1-AT deficiency depend on the patient’s personal habits but are most severe in patients who smoke tobacco.

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