Celiac Disease Screening#

A positive TTG IgA strongly suggests celiac disease, but it is not yet a confirmed diagnosis. In adults, the standard next step is a small-bowel biopsy through upper endoscopy by a gastroenterologist. You would arrange this through your family doctor or a walk-in clinic; TeleTest does not arrange gastroenterology referrals.

Important: Do not start a gluten-free diet between the positive blood test and the biopsy. The biopsy looks for damage caused by gluten - if you remove gluten, the lining starts to heal and the biopsy can come back falsely negative, leaving you without a definitive diagnosis.

A borderline TTG (just above the cutoff) is less specific than a strongly positive result. Possible interpretations:

• Early celiac disease
• Partial response to a partly gluten-free diet
• Another autoimmune condition causing a non-specific positive
• A laboratory variation

Next steps usually include:

• Repeat TTG IgA in 1 to 3 months on a continued gluten-containing diet
• EMA IgA (more specific confirmatory test)
• In-person assessment with a gastroenterologist for possible biopsy (arranged through your family doctor or a walk-in clinic; TeleTest does not arrange gastroenterology referrals)

About 2 to 3% of people have selective IgA deficiency, where the body produces less of the IgA antibody type than usual. By itself, IgA deficiency is usually not a health problem, but it complicates celiac testing because TTG IgA can be falsely negative.

When total IgA is low, your clinician will order:

• TTG IgG or
• DGP IgG (deamidated gliadin peptide IgG)

These IgG-based tests do not rely on the IgA antibody system and give a reliable result in someone with IgA deficiency.

A negative blood test on a gluten-containing diet makes celiac disease unlikely - but other conditions cause similar symptoms:

• Non-celiac gluten sensitivity: symptoms improve off gluten, but blood tests and biopsy are negative. This is a real entity but the cause is not fully understood.
• Irritable bowel syndrome (IBS): very common, often improves with low-FODMAP diet, fibre adjustments, or stress management.
• Lactose or other carbohydrate intolerance.
• Small intestinal bacterial overgrowth (SIBO).
• Inflammatory bowel disease (Crohn's, ulcerative colitis): screened with different blood tests, stool tests, and colonoscopy.
• Other food sensitivities, microscopic colitis, bile-acid malabsorption.

Discuss persistent symptoms with a clinician - further investigation (calprotectin, lactose breath test, colonoscopy) may be appropriate.

The standard blood test will not be reliable in someone already on a gluten-free diet. Two options:

1. Gluten challenge: Restart a regular gluten-containing diet for at least 6 to 8 weeks (ideally 12), then test. This is uncomfortable but gives a reliable answer.
2. HLA-DQ2 / HLA-DQ8 genetic testing: Does not require eating gluten. A negative result essentially rules out celiac disease. A positive result is inconclusive (about 30 to 40% of the general population is HLA-positive without having celiac).

For most people who have improved on a gluten-free diet without a formal diagnosis, the practical recommendation is: continue gluten-free if it helps and you can maintain it long-term, or pursue a gluten challenge if you need a confirmed diagnosis (for example, for family screening, school accommodations, disability benefits, or your own peace of mind).

Dermatitis herpetiformis is a very itchy skin rash with small blisters and bumps, most often on the elbows, knees, buttocks, and scalp. It is the skin manifestation of celiac disease and affects about 1 in 4 people with celiac. The diagnosis is usually confirmed by a skin biopsy showing IgA deposits.

Treatment is the same lifelong gluten-free diet used for intestinal celiac disease. Specific medication may be added temporarily to control the rash while gluten withdrawal takes effect.

Celiac disease is associated with:

• Iron, B12, folate, vitamin D, calcium, and zinc deficiencies
• Osteoporosis and increased fracture risk
• Type 1 diabetes
• Autoimmune thyroid disease (Hashimoto's, Graves')
• Other autoimmune conditions (autoimmune liver disease, Sjögren's syndrome, lupus)
• Infertility and recurrent miscarriage
• Some lymphomas of the small intestine (uncommon, and risk falls with a strict gluten-free diet)
• Reduced absorption of medications taken orally

Most of these are reduced or prevented with a strict, lifelong gluten-free diet.

First-degree relatives (parent, sibling, child) of someone with celiac disease have about a 5 to 10% risk of also having celiac. Canadian and international guidelines recommend testing all first-degree relatives at least once, even without symptoms - usually starting around school age and again in adulthood. Children with symptoms should be tested earlier.

TeleTest does not currently provide pediatric care - children should be tested through their family doctor or pediatrician.

Undiagnosed celiac disease is associated with infertility, miscarriage, and lower birth weight. If you have symptoms suggesting celiac and are planning pregnancy, screening before conception is reasonable. If you already have a celiac diagnosis, a strict gluten-free diet during pregnancy is essential, and your obstetric provider should be informed.

TeleTest does not currently manage prenatal care.

In adults, yes - biopsy is the gold standard. In children, some pediatric guidelines now allow a "no-biopsy" diagnosis under very specific conditions (very high TTG, positive confirmatory EMA, classic symptoms, and HLA confirmation), but this is a pediatric pathway and is done by a pediatric gastroenterologist.

Possible explanations:

• You had already started reducing gluten before the biopsy (the most common explanation).
• The biopsy missed patchy damage (the gastroenterologist usually takes multiple biopsy samples to reduce this).
• You have potential celiac disease - antibodies are positive but the intestine has not yet shown damage. This sometimes progresses to full celiac later and is monitored.
• The TTG was a non-specific positive (less likely if it was strongly positive).

Your gastroenterologist will decide whether to repeat biopsy, monitor, or proceed as if celiac is confirmed based on the full clinical picture.

A strict, lifelong gluten-free diet is currently the only proven treatment. Several investigational treatments (medications that break down gluten in the gut, immune-modulating treatments) are in clinical trials but none are approved for routine use in Canada. Even a small amount of gluten can trigger immune damage in people with celiac disease, so "mostly gluten-free" is not sufficient.

A registered dietitian with celiac expertise is invaluable for new diagnoses. Canadian Celiac Association local chapters and support groups also help.

Once on a strict gluten-free diet, follow-up usually includes:

• TTG IgA repeated every 6 to 12 months until normalized (this usually takes 1 to 2 years of strict gluten avoidance)
• Nutritional bloodwork (iron studies, B12, folate, vitamin D) at diagnosis and then annually
• CBC at diagnosis and annually
• Bone-density (DEXA) scan at diagnosis (especially in adults) and at intervals afterward
• Repeat biopsy in some cases if antibodies do not normalize or symptoms persist

A persistently elevated TTG on a gluten-free diet usually means hidden gluten exposure rather than treatment failure. A dietitian can help identify hidden sources.

There is no cure - but a strict gluten-free diet controls symptoms, allows the intestine to heal, normalizes blood antibody levels, and prevents most complications. With good adherence, people with celiac disease have a similar life expectancy to those without celiac.

Celiac disease is caused by an interaction between genetics (HLA-DQ2 or HLA-DQ8) and an environmental trigger (gluten). The exact mechanism is complex - the immune system mis-reads a small peptide from gluten as a threat and attacks the lining of the small intestine. Why some people with the genetic background develop celiac and others do not is still being studied.