When preparing for a celiac blood test, fasting is not required. Unlike some medical tests that necessitate dietary restrictions beforehand, the primary consideration for a celiac blood test involves your gluten consumption.
Understanding Celiac Blood Tests
Celiac blood tests are designed to detect specific antibodies produced by the immune system in response to gluten consumption. In individuals with celiac disease, the immune system mistakenly identifies gluten as a threat, leading to the production of these autoantibodies. The main antibodies screened include tissue transglutaminase IgA (tTG-IgA), endomysial antibodies (EMA), and deamidated gliadin peptide (DGP) IgA and IgG.
The tTG-IgA test is the initial and most sensitive screening tool for most adults and children over two years old. If a person has an IgA deficiency, IgG-based tests like tTG-IgG or DGP-IgG are used because IgA tests might yield false negative results. These blood tests serve as a screening method to identify individuals who may have celiac disease, prompting further investigation.
Preparing for Your Celiac Blood Test
Fasting is not necessary for a celiac blood test. The most important aspect of preparation is to maintain a regular, gluten-containing diet for several weeks leading up to the test. This is often referred to as a “gluten challenge.” The reason for this is that the immune system needs to be actively exposed to gluten to produce the antibodies that the test measures.
If you have already adopted a gluten-free diet, reintroducing gluten is essential for accurate results. It is recommended to consume about 3 to 10 grams of gluten daily, which is roughly equivalent to 1.5 to 5 slices of wheat bread, for a period of 6 to 8 weeks before the test. Consuming less gluten or for a shorter duration might still cause changes in the small intestine or positive antibodies in some individuals, but a higher intake for the recommended period increases the likelihood of diagnostic changes. It is important to discuss the specific amount and duration of gluten intake with your healthcare provider, especially if you experience severe symptoms during this period. Certain medications or other medical conditions could also influence test results, so it is advisable to inform your doctor about any current prescriptions or health issues.
Interpreting Your Celiac Blood Test Results
After your blood test, results indicate whether antibodies are positive, negative, or borderline. A positive result suggests the presence of celiac disease markers, but it does not confirm a diagnosis on its own. A negative result means antibodies were not detected, lowering the probability of celiac disease.
Regardless of the initial blood test outcome, if celiac disease is suspected, further confirmation is needed. This involves an upper endoscopy with a biopsy of the small intestine to check for characteristic damage to the villi, the small finger-like projections that absorb nutrients. It is recommended to discuss your specific blood test results with a healthcare professional, who can interpret them in the context of your symptoms and medical history, and guide you on the next appropriate steps.