Turnaround Time: 14 Days
Test Type: Kit-Based, Blood
From a simple finger stick, the Bloodspot IgG4 Food Antibodies Profile offers a less invasive alternative to a blood draw in determining IgG4 food reactions.
Easy to implement in any practice and great option for follow-up testing.
- Does not require venipuncture
- Cost-effective testing
- Easy for patients to use at home
Offers the same levels of precision and reproducibility as standard methodsCirculating IgG4 food antibodies are not diagnostic for a specific condition but indicate an immune response to the presence of food antigens. IgG4 antibodies are produced in a delayed hypersensitivity reaction, which can occur one to seven days after exposure to the offending food antigen. These reactions are difficult to detect since there may be no obvious association with the offending food. Commonly reported symptoms for elevated IgG4 responses involve GI tract, skin, nose, and throat. In contrast, the immune response could be a normal response that would not necessarily cause symptoms. Therefore, test results should always be viewed in the context of the overall clinical picture.
Conditions associated with IgG4 food antibodies:
- Eosinophilic esophagitis
- Irritable bowel syndrome/ GI symptoms
- Crohn's disease
Of the 5 classes of antibodies, immunoglobulin G (IgG) is the most abundant circulating antibody, making up 75% of antibodies. The other classes of antibodies include IgE, IgA, IgM, and IgD. IgG has 4 subclasses including IgG1, IgG2, IgG3, and IgG4 making up 66%, 23%, 7%, and 4% of the IgG antigen pool respectively.
IgG4 is unique compared to the other subclasses. It acts as a blocking antibody to the allergy-producing IgE antibody, and with the IgE antibody, is considered part of the Th2 response. Increases in IgG4 levels correlate with improved clinical responses since it blocks the IgE anitbody allergic response; it is involved in establishing immunologic tolerance to that food. IgG4 does not activate complement compared to IgE3. Some speculate that IgG4 may be produced initially to attenuate IgE-mediated disease, but ultimately results in a pro-inflammatory process in susceptible atopic hosts.
• It is not necessary for the patient to fast
• It is not necessary to discontinue nutritional supplements prior to this test.
Abnormalities that may be found will reveal special needs that have not been met by
recent dietary and supplemental intake.
• The use of immunosuppressive drugs, such as cortisone, can give false negative
results. Discontinue the use of such drugs for 60 days before testing to allow antibody
reactions to be seen.
Bloodspot finger stick collection card.
1. Write patient’s first and last name, date of birth, gender and date of collection on
the Test Requisition Form (located in the pouch on top of the Specimen Collection
Kit Box), as well as where indicated on the absorbent collection card with the four
circles, using a permanent marker.
• IMPORTANT: To ensure accurate test results you must provide the requested
2. Complete the Test Requisition Form. Fill in “Date Specimen
Collected” on the Test Requisition Form under section #4. Fold and place the form inside the postage paid envelope.
3. Remove the clear cover from the lancet. One end of the lancet
has a small hole in the center; this will be the end that you push against your finger to engage the needle.
4. Warm your hands under warm water for a few minutes. Dry hands, then select your middle finger. Gently massage the entire length of the finger to increase the temperature and improve circulation.
5. Clean the tip of your finger with the alcohol pad.
6. Hang your arm down and gently shake your fingers a few seconds to increase blood pools in the finger.
7. Hold your hand lower than heart level; again gently massage the lower portion of the finger. Firmly grasp the lower portion of the finger for a few seconds to restrict return circulation.
8. Choose a site on the middle fingertip. Push the red tip end of the lancet firmly against your fingertip to depress the tip and release the needle. The needle will immediately retract safely after depression.
9. Dispose of the lancet in a suitable container (out of the reach of children and pets).
10. Using your thumb, gently massage entire length of the pricked finger to form repeated blood drops. As each drop forms, touch the tip of the drop to a circle on the absorbent collection card. Do
DO NOT TOUCH FINGERTIP TO THE CARD.
11. Repeat until blood has soaked to the border of the circle on the absorbent
collection card. Continue this procedure for all Four circles. Check the back of the card. Compare all blood saturated circles to the illustration shown as “YES” (see insert). Both the front and back of the card should look the same as the “YES” illustration.
12. If you are unable to get sufficient blood from the first collection, Return to step
3 using a different finger. To increase blood pools in the finger, the yellow rubber
band may be used. After you warm your hands under water for a few minutes, Wrap the yellow rubber band twice around your forearm - about where you would
wear a watch, then proceed to step 5. When finished, remove the yellow rubber
13. If necessary, use the absorbent pad to dry the site on your finger after your collection. Use the enclosed adhesive bandage as needed.
14. Allow absorbent collection card to air dry overnight, approximately 24 hours,
before placing in the resealable plastic bag with desiccant/moisture absorbent pack for shipping. If the card is not completely dry, your sample may be unusable.