Sorted By Test Name - Mayo Medical Laboratories

CA1A
8835
A1ATR
83050
content, alpha-1-acid glycoprotein is identical to immunosuppressive
acidic protein (IAP).
Test Performed by
Focus Diagnostics
5785 Corporate Avenue
Cypress, CA 90630-4750
Alpha-1-Antitrypsin Clearance, Feces and Serum
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
Interpretation: Elevated alpha-1-antitrypsin (A1A) clearance suggests excessive gastrointestinal
protein loss. (The positive predictive value of the test has been found to be 97.7% and the negative
predictive value is 75%.) Patients with protein-losing enteropathies generally have A1A clearance values
>50 mL/24 hours and A1A stool concentrations >100 mg/mL. Borderline elevations above the normal
range are equivocal for protein-losing enteropathies.
Reference Values:
Clearance: < or =27 mL/24 hours
Fecal alpha-1-antitrypsin concentration: < or =54 mg/dL
Serum alpha-1-antitrypsin concentration: 100-190 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
1981;81:777-780 2. Crossley JR, Elliott RB: Simple method for diagnosing protein-losing enteropathy. Br
Med J 1977;1:428-429 3. Perrault J, Markowitz H: Protein-losing gastroenteropathy and the intestinal
clearance of serum alpha-1-antitrypsin. Mayo Clin Proc 1984;59:278-279
Alpha-1-Antitrypsin Deficiency Profile
Clinical Information: Alpha-1-antitrypsin (A1A) is a protein that inhibits the enzyme neutrophil
elastase. It is predominantly synthesized in the liver and secreted into the bloodstream. The inhibition
function is especially important in the lungs because it protects against excess tissue degradation. Tissue
degradation due to A1A deficiency is associated with an increased risk for early onset panlobar
emphysema, which initially affects the lung bases (as opposed to smoking related emphysema, which
presents with upper lung field emphysema). Patients may become symptomatic in their 30's and 40's. The
most frequent symptoms reported in a National Institute of Health study of 1,129 patients with severe
deficiency (mean age 46 years) included cough (42%), wheezing (65%), and dyspnea with exertion
(84%). Many patients were misdiagnosed as having asthma. It is estimated that approximately one sixth
of all lung transplants are for A1A deficiency. Liver disease can also occur, particularly in children; it
occurs much less commonly than emphysema in adults. A1A deficiency is a relatively common disorder
in Northern European Caucasians. The diagnosis of A1A deficiency is initially made by quantitation of
protein levels in serum followed by determination of specific allelic variants by isoelectric focusing (IEF).
While there are many different alleles in this gene, only 3 are common. The 3 major alleles include: M
(full functioning, normal allele), S (associated with reduced levels of protein), and Z (disease-causing
mutation associated with liver disease and premature emphysema). The S and Z alleles account for the
majority of the abnormal alleles detected in affected patients. As a codominant disorder, both alleles are
expressed. An individual of SZ or S-null genotype may have a small increased risk for emphysema (but
not liver disease) due to slightly reduced protein levels. On the other hand, an individual with the ZZ
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