Alpha-1-Antitrypsin
Label Mnemonic: A1AC
Epic code: LAB2565
Downtime form: A-1a Doctor/Provider Orders - Pathology Core and Specialty Care Nursery
Commercial Mail-out Laboratory
5231 RCP
356-8593
Specimen(s):
Feces and Serum
Both feces and serum are required.

Blood must be drawn during the stool collection period.
Specimen Instructions:
Feces and serum should be shipped together. Specimens shipped separately may delay testing.
Collection Medium:
and
24, 48, 72 hour fecal specimen, stool container(s) Red top tube 5 mL (Clot Activator)
Minimum:
Collect a 24 hr fecal collection. If no specimen is obtained within 24 hours, extend collection time to 48 to 72 hours. Document time frame.

Also collect 1.0 mL serum (Min: 0.5 mL) from red top or serum gel tube.

Fecal specimen must be collected in special containers available from Mailouts at 356-8395 Monday-Friday, or Specimen Control (6240 RCP) at 356-3527. Draw serum sample during stool collection period. In the absence of either a 24-hour stool collection or a contemporary serum specimen, the fecal concentration of alpha-1-antitrypsin (A1A) can be used as a surrogate marker. The clearance is preferred in order to normalize the large range of serum A1A concentrations and the variability in random stool A1A concentration.
Rejection Criteria:
Specimens other than stool plus serum.
Delivery Instructions:
Submit specimen to laboratory as soon as possible after collection period is completed.
Testing Schedule:
Test performed Monday through Saturday.
Turn Around Time:
1 day upon receipt at reference laboratory
Reference Range:
Clearance: < or = 27 mL/24 hours
Fecal alpha-1-antitrypsin concentration: < or = 54 mg/dL
Serum alpha-1-antitrypsin concentration: 100 - 190 mg/dL
Interpretive Data:
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 greater than 50 mL/24 hours and A1A fecal concentrations above 100 mg/mL.

Borderline elevations above the normal range are equivocal for protein-losing enteropathies.
Comments:
Useful for: Diagnosing protein-losing enteropathies

Cautions: In the absence of either a 24-hour fecal collection or a contemporary serum specimen, the fecal concentration of alpha-1-antitrypsin (A1A) can be used as a surrogate marker. The clearance is preferred in order to normalize the large range of serum A1A concentrations and the variability in random fecal A1A concentration.
Methodology:
Nephelometry
CPT Code:
82103 x2