Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

A1APP
26953
A1AF
182
Butz ML, et al: Diagnosis of alpha-1-antitrypsin deficiency: an algorithm of quantification, genotyping,
and phenotyping. Clin Chem 2006;52:2236-2242
Alpha-1-Antitrypsin Phenotype
Clinical Information: Alpha-1-antitrypsin (A1A) is the most abundant serum protease inhibitor
and inhibits trypsin and elastin, as well as several other proteases. The release of proteolytic enzymes
from plasma onto organ surfaces and into tissue spaces results in tissue damage unless inhibitors are
present. Congenital deficiency of A1A is associated with the development of emphysema at an
unusually early age and with an increased incidence of neonatal hepatitis, usually progressing to
cirrhosis. See "Alpha-1-Antitrypsin-A Comprehensive Testing Algorithm" in Special Instructions.
Useful For: Identification of homozygous and heterozygous phenotypes of the alpha-1-antitrypsin
deficiency.
Interpretation: There are >40 Alpha-1-antitrypsin (A1A) phenotypes (most of these are associated
with normal quantitative levels of protein). The most common normal phenotype is M (M, M1, or M2),
and >90% of Caucasians are homozygous M (MM) genotype. A1A deficiency is usually associated with
the Z phenotype (ZZ genotype), but genotypes such as SS and SZ are also associated with decreased
A1A levels.
Reference Values:
ALPHA-1-ANTITRYPSIN
100-190 mg/dL
ALPHA-1-ANTITRYPSIN PHENOTYPE
Most normal individuals have the M phenotype (M, M1, or M2). Over 99% of M phenotypes are
genotypically MM. In the absence of family studies, the phenotype (M) and quantitative level can be
used to infer the genotype (MM). The most common alleles associated with a quantitative deficiency are
Z and S. The reports for the rare alleles will indicate whether or not they have been associated with
reduced quantitative levels.
Clinical References: Morse JO: Alpha-1-antitrypsin deficiency. N Engl J Med
1978;299:1045-1048; 1099-1105.
Alpha-1-Antitrypsin, Random, Feces
Clinical Information: Alpha-1-antitrypsin (A1A) is resistant to degradation by digestive enzymes
and is, therefore, used as an endogenous marker for the presence of blood proteins in the intestinal tract.
A1A clearance is reliable for measuring protein loss distal to the pylorus. Gastrointestinal protein
enteropathy has been associated with regional enteritis, sprue, Whipple's intestinal lipodystrophy,
gastric carcinoma, allergic gastroenteropathy, intestinal lymphangiectasia, constrictive pericarditis,
congenital hypogammaglobulinemia, and iron deficiency anemia associated with intolerance to cow's
milk.
Useful For: Diagnosing protein-losing enteropathies, especially when used in conjunction with
serum alpha-1-antitrypsin (A1A) levels as a part of A1A clearance studies (see #8835
"Alpha-1-Antitrypsin Clearance, Feces and Serum"; preferred test)
Interpretation: Patients with protein-losing enteropathies generally have alpha-1-antitrypsin stool
concentrations >100 mg/mL. Borderline elevations above the normal range are equivocal for
protein-losing enteropathies.
Reference Values:
< or =54 mg/dL
Clinical References: 1. Florent C, L'Hirondel C, Desmazures C, et al: Intestinal clearance of alpha
1-antitrypsin. A sensitive method for the detection of protein losing enteropathy. Gastroenterology
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