Alpha1-Proteinase Inhibitor (α1-PI)
Dogs: 2.2 - 18.7 µg/g fecal material
A mean three-day α1-PI of ≥13.9 μg/g feces or a
α1-PI of one individual sample of ≥21.0 μg/g feces is
Please note, this assay has only been
clinically validated for adult dogs (dogs that are one year of age
or older). Fecal α1-PI concentrations have been shown to
be increased in young healthy puppies. The reference range does
therefore not apply for puppies.
Cats: This assay is no longer available as of Nov 1,2014. We
apologize for any inconvenience.
What is the principle behind this test?
As a result of GI disease, the integrity of the intestinal
mucosa may be compromised and proteins can be lost into the
gastrointestinal lumen. Alpha1-PI is a plasma protein,
similar in size to albumin, and is lost into the gastrointestinal
lumen at about the same rate as albumin and other plasma proteins,
such as antithrombin III. But unlike most other plasma proteins,
α1-PI is a proteinase inhibitor and thus able to resist
degradation by digestive and bacterial proteinases (see Figure 1).
Alpha1-PI remains essentially intact in the
gastrointestinal lumen and can, therefore, be detected in feces by
use of an immunoassay.
Gastrointestinal protein loss can be associated with a variety
of gastrointestinal and systemic disorders such as idiopathic
inflammatory gastroenteropathies, gastrointestinal neoplasia,
foreign bodies, intussusceptions, small intestinal bacterial
overgrowth (SIBO), infectious enteritis, immune-mediated diseases,
or intestinal lymphangiectasia. Therefore, therapy and outcome
depend on the underlying disease.
A: After being lost into the intestinal lumen,
albumin and other plasma proteins are readily degraded by digestive
and bacterial proteinases. The resulting degradation products are
not immunoreactive and thus cannot be measured by
B: Alpha1-PI has a similar molecular
size to albumin. Unlike albumin, α1-PI resists
degradation by proteinases present in the intestinal lumen and can
thus be detected in feces by immunoassays.
How do fecal samples for this assay have to be collected?
Special pre-weighed fecal tubes have to be used and are
available through the Gastrointestinal Laboratory. Fresh fecal
samples (one gram each) from naturally-passed defecations from 3
consecutive days should be collected as soon as possible after
defecation. Each sample tube must be immediately frozen after
collection. All 3 samples should then be shipped frozen by
Shipping guidelines for canine Alpha1-Proteinase
Please note: Samples for this test must
arrive frozen at the laboratory in order to avoid
breakdown of proteins leading to false negative results. In our
experience, samples have the best chances for arriving frozen when
shipped either with dry ice or at least in a styrofoam container
with several frozen gel ice packs. Unfortunately cardboard
containers do not insulate well enough against
average Texas temperatures. These samples also must be shipped
overnight by either FedEx or UPS. Please do not
use the US Postal Service as these samples generally tend to
experience significant delays and are not delivered directly to the
laboratory. International shipments for this test must be sent on
dry ice. Please do not ship samples later than on a
Thursday since we are not able to receive any packages on
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