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  PTD - 160

Test Directory -  Faecal Alpha-1 Antitrypsin

Clinical Indications

Inflammatory bowel conditions can lead to a protein-losing enteropathy in which there is increased loss of plasma proteins into the gut. Alpha-1 antitrypsin, a protease inhibitor, is relatively resistant to breakdown by proteolytic enzymes found in the gut and may pass relatively unchanged into the faeces. 
Levels of alpha-1 antitrypsin in faeces may be used as a guide to the extent of protein loss into the gut, although some studies have show a high frequency of false negative results. Nevertheless, a positive finding may be useful in confirming a diagnosis of protein-losing enteropathy and monitoring progress of the disease. A negative result does not exclude protein-losing enteropathy.
It is recommended that a serum alpha-1 antitrypsin is measured to ensure normal serum levels.

Request Form

Combined Pathology Blood form (Yellow/Black)

Availability

Referred test: Analysed by Protein Reference Unit, St Georges Hospital, if specific criteria met.

Specific Criteria

Requested by Consultant Gastroenterologist or if agreed with Consultant Biochemist.

Turnaround Time

2 weeks

Specimen

Faeces 

Volume

10 gram minimum (approx. size of gooseberry).

Container

Plastic universal (blue-topped)
Samples must be transported to laboratory immediately after collection

Causes for Rejection

Delay in sample reaching the laboratory. Not meeting specific criteria for analysis.

Reference Range

Less than 5 mg/g dry weight faeces.
This range assumes normal serum alpha-1 antitrypsin levels and will apply to the PI M phenotype only.

Interpretation

False negative results may occur from protein degradation due to incorrect collection or alpha-1 antitrypsin deficiency. False positive results may occur in G.I. bleeding.

Lab. Handling

Referral: Test code SASOD. Freeze immediately and store in the separating freezer (CB40) at -20C. Sample must be sent frozen to the referral laboratory or BPRO and save in separating freezer (CB40) at -20C.


Version 1.1 / June 2015                                                                                                          Approved by: Consultant Biochemist