Pork (Sus d 1) IgE Test · Blood

If you have ever flushed, broken out in hives, wheezed, or had a stomach reaction after eating pork, your body may be making antibodies that treat pig protein as a threat. This blood test looks for one of those antibodies, called Sus d 1 IgE (an immune protein your body makes against a specific pig allergen).

It is most useful for people who suspect pork allergy, who work around pigs or raw pork, or who are sensitized to cats and notice reactions when eating pork. The result helps connect a symptom to a specific trigger so you can make confident decisions about what to eat and what to avoid.

What This Test Actually Measures

This is a blood test for IgE (immunoglobulin E, the antibody class that drives classic allergic reactions) directed at pork allergens. Sus d 1 is a name used in allergen databases for a pig-derived protein. In practice, allergy labs measure IgE to extracts of pork meat or to pig serum albumin (the most studied pork allergen component). The result tells you whether your immune system has built a targeted antibody response to pig protein.

A positive result means you are sensitized. It does not by itself mean you will have a reaction every time you eat pork, which is why the result is interpreted alongside your symptom history.

Why Pork Allergy Is Worth Taking Seriously

Pork allergy can show up in three distinct patterns, and a specific IgE test helps sort them out. The first is classic immediate allergy: hives, swelling, wheezing, or anaphylaxis within minutes to an hour of eating pork. A clinical series of slaughterhouse workers documented this pattern, with asthma, rhinitis, and contact urticaria after raw-pork exposure, confirmed by positive skin prick tests, elevated pork-specific IgE, and positive nasal provocation tests with pork extract.

The second is pork-cat syndrome, where people who are first sensitized to cat develop reactions to pork because the IgE that recognizes cat serum albumin also binds to a similar protein in pig. In an initial U.S. case series of 8 patients, every patient had IgE to both cat and pork serum albumin, and reactions ranged from oral itching to anaphylaxis. A separate case report described pork-cat syndrome presenting as food-dependent exercise-induced anaphylaxis, where pork was tolerated at rest but triggered systemic reactions when paired with exercise.

The third is alpha-gal syndrome, a delayed allergy to red meats (including pork) caused by IgE to a sugar called galactose-alpha-1,3-galactose. Reactions typically appear 3 to 7 hours after eating mammalian meat, not minutes. A foundational case series of 24 patients described delayed anaphylaxis, angioedema, or hives after beef, pork, or lamb, with fewer episodes once patients followed an avoidance diet. A U.S. surveillance analysis identified more than 34,000 people with positive alpha-gal testing between 2010 and 2018, with cases concentrated in southern, midwestern, and mid-Atlantic regions where the Amblyomma americanum tick is common.

Distinguishing Pork Allergy From Alpha-Gal Syndrome

This is the key interpretive question for anyone reacting to pork, because the diseases look different and call for different avoidance strategies. Pork-specific IgE that targets pig protein points toward classic pork allergy or pork-cat syndrome. Alpha-gal IgE points toward delayed red meat allergy that also affects beef and lamb.

In a study of 51 Korean adults, IgE to cetuximab and bovine thyroglobulin (both used to measure alpha-gal antibodies) accurately separated alpha-gal syndrome from immediate classical meat allergy and from asymptomatic sensitization. In a South African study of 157 people in a region with high reported red meat allergy, alpha-gal IgE levels and the ratio of alpha-gal IgE to total IgE strongly correlated with oral food challenge-confirmed meat allergy. The clinical implication: if you react to pork, a pork-specific IgE result is most informative when paired with an alpha-gal IgE result and, when relevant, a cat allergen test.

Connection to Cat Allergy

Cat owners with allergic symptoms have an unusually high chance of reacting to pork through pork-cat syndrome. The cross-reactivity was first documented in a study of 10 patients with allergic reactions to pork, where cat serum albumin IgE was identified as a marker for potential cross-sensitization to pig serum albumin and other mammal albumins. A later case described recurrent hives in a 6-year-old with cat allergy whose cat albumin IgE cross-reacted with pork.

Broader research on furry-animal cross-reactivity in 211 adults with rhinitis showed that serum albumin sensitization links sensitization across cats, dogs, and other mammals, and is associated with more rhinitis symptoms. If you are a cat owner who reacts to pork, testing for pork-specific IgE together with cat-specific tests (especially the cat albumin component, Fel d 2) gives you a clear picture of whether your pork reactions are driven by cross-reactivity rather than a primary pork allergy.

Tracking Your Trend

Allergen-specific IgE is a marker of sensitization, not a fixed number. Levels can rise with continued exposure, drift down during sustained avoidance, and shift after major immune events. A single reading establishes whether you are sensitized; serial readings tell you whether that sensitization is stable, intensifying, or resolving.

A practical cadence: get a baseline now, retest in 6 to 12 months if you are actively avoiding pork or pursuing treatment, and then at least every 1 to 2 years if symptoms persist or change. Pair each test with notes on what you ate, any reactions, and tick or pet exposures, because the IgE number on its own does not tell the full story.

Decision Pathway for an Out-of-Pattern Result

A positive pork-specific IgE is the start of a workup, not the end. The next step depends on what surrounds it. If you have had clear reactions to pork, an allergist (a doctor who specializes in allergic conditions) should be the next stop, since interpretation depends on the clinical pattern.

• Pair with alpha-gal IgE: if your reactions are delayed by hours, alpha-gal testing (often via bovine thyroglobulin or cetuximab IgE) is essential to distinguish red meat allergy from classic pork allergy.
• Pair with cat-related testing: if you own a cat or react to other mammalian meats, ask about cat dander and Fel d 2 (cat serum albumin) IgE to assess pork-cat syndrome.
• Pair with total IgE: the ratio of allergen-specific to total IgE can sharpen interpretation, particularly for alpha-gal syndrome.
• Consider provocation testing: if results are ambiguous, an oral food challenge under medical supervision is the most definitive way to confirm or rule out true clinical allergy.

What this means for you: a positive pork IgE plus a delayed reaction pattern plus a tick bite history points toward alpha-gal syndrome. A positive pork IgE plus a cat in the home plus immediate reactions points toward pork-cat syndrome. A positive pork IgE without either context points toward classic pork allergy. Each pathway has a different avoidance strategy.

When Results Can Be Misleading

• Sensitization without symptoms: a positive IgE means your immune system has made the antibody, not that you will react when you eat pork. Some sensitized people tolerate pork without issue.
• Component mismatch: if your reactions are delayed (hours, not minutes), the relevant test may be alpha-gal IgE rather than pork extract IgE. A negative pork IgE does not rule out alpha-gal syndrome.
• Cross-reactive confusion: a positive pork IgE in someone with strong cat sensitization may reflect cross-reactivity rather than a primary pork allergy. Cat albumin and pig albumin look similar enough to your antibodies that one test can flag both.
• Recent illness or vaccination: general immune activation around the time of testing can subtly shift IgE values, though specific IgE is considered relatively stable from day to day.