A B C D E F G H I J K L M N O P Q R S T U V W X Y Z # |
Alpha-1-Antitrypsin, Random Feces
Test Code14628
Alias/See Also
LAB01136
CPT Codes
82103
Preferred Specimen
10 grams random stool
Instructions
Collect fresh stool in a plastic leak-proof container. Adult and older children patients can collect the specimen by passing feces into plastic wrap stretched loosely over the toilet bowl. Then transfer 10 g of the stool specimen into the plastic container. With young children and infants wearing diapers, the diaper should be lined with clean plastic wrap to prevent absorption. A pediatric urine bag can be attached to the child to ensure that the stool specimen is not contaminated with urine. Then transfer 10 g of the stool specimen from the plastic lined diaper to the plastic container. Do not submit the diaper itself. Freeze and ship frozen.
Transport Container
Plastic screw-cap container
Transport Temperature
Frozen
Specimen Stability
Room temperature: Unacceptable
Refrigerated: 8 days
Frozen: 28 days
Refrigerated: 8 days
Frozen: 28 days
Methodology
Nephelometry
Setup Schedule
Daily
Report Available
3-4 days
Reference Range
<55 mg/dL
Clinical Significance
This test measures alpha-1-antitrypsin (AAT) concentration in a random stool specimen and may help screen for protein-losing enteropathy [1]. An AAT level measured in a 24-hour stool specimen and interpreted jointly with a simultaneous blood AAT level is generally preferred for the diagnosis of protein-losing enteropathy [2].
Protein-losing enteropathy is a disorder caused by inflammation or destruction of intestinal mucosa and subsequent increased loss of plasma protein through the gastrointestinal tract. Conditions associated with protein-losing enteropathy include but are not limited to inflammatory bowel disease, lymphoma, Whipple disease, systemic lupus erythematosus, and food allergies [3]. Measurement of radioactive albumin is the "gold standard" for gastrointestinal protein loss but is rarely performed because of the high cost and complex methodology [4]. AAT has a molecular weight similar to that of albumin and is resistant to proteolysis. Therefore, the excretion of AAT in stool can be used to estimate protein loss in the gastrointestinal tract [2,3].
Low stool AAT levels may also be caused by AAT deficiency or impaired hepatic synthesis of AAT; thus, they must be interpreted in conjunction with plasma AAT levels [3]. Abnormal results in patients with intestinal blood loss need to be interpreted carefully owing to the possibly increased AAT clearance [4].
An AAT level measured in a random stool specimen may not accurately reflect daily AAT excretion [2]. AAT clearance, calculated from AAT concentrations in a 24-hour fecal specimen and a serum specimen, is more reliable for estimating protein loss [5].
The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.
References
1. Thomas DW, et al. Gastroenterology. 1981;80(4):776-782.
2. Florent C, et al. Gastroenterology. 1981;81(4):777-780.
3. Sherwood RA, et al. Gastric, intestinal, and pancreatic function. In: Rifai R, et al, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier Inc; 2022.
4. Strygler B, et al. Gastroenterology. 1990;99(5):1380-1387.
5. Levitt DG, et al. Clin Exp Gastroenterol. 2017;10:147-168.
Protein-losing enteropathy is a disorder caused by inflammation or destruction of intestinal mucosa and subsequent increased loss of plasma protein through the gastrointestinal tract. Conditions associated with protein-losing enteropathy include but are not limited to inflammatory bowel disease, lymphoma, Whipple disease, systemic lupus erythematosus, and food allergies [3]. Measurement of radioactive albumin is the "gold standard" for gastrointestinal protein loss but is rarely performed because of the high cost and complex methodology [4]. AAT has a molecular weight similar to that of albumin and is resistant to proteolysis. Therefore, the excretion of AAT in stool can be used to estimate protein loss in the gastrointestinal tract [2,3].
Low stool AAT levels may also be caused by AAT deficiency or impaired hepatic synthesis of AAT; thus, they must be interpreted in conjunction with plasma AAT levels [3]. Abnormal results in patients with intestinal blood loss need to be interpreted carefully owing to the possibly increased AAT clearance [4].
An AAT level measured in a random stool specimen may not accurately reflect daily AAT excretion [2]. AAT clearance, calculated from AAT concentrations in a 24-hour fecal specimen and a serum specimen, is more reliable for estimating protein loss [5].
The results of this test should be interpreted in the context of pertinent clinical and family history and physical examination findings.
References
1. Thomas DW, et al. Gastroenterology. 1981;80(4):776-782.
2. Florent C, et al. Gastroenterology. 1981;81(4):777-780.
3. Sherwood RA, et al. Gastric, intestinal, and pancreatic function. In: Rifai R, et al, eds. Tietz Textbook of Laboratory Medicine. 7th ed. Elsevier Inc; 2022.
4. Strygler B, et al. Gastroenterology. 1990;99(5):1380-1387.
5. Levitt DG, et al. Clin Exp Gastroenterol. 2017;10:147-168.
Performing Laboratory
Quest Diagnostics Nichols Institute-Chantilly VA |
14225 Newbrook Drive |
Chantilly, VA 20151-2228 |