Medical Analysis

Understanding Gluten: Composition, Sources, and Clinical Impact

Gluten constitutes more than 85% of the protein found in wheat. It is primarily a conglomerate of two proteins: gliadin and glutenin. Because these proteins are particularly rich in the amino acids glutamine and proline, they are also classified as prolamines. Gluten is prevalent in many common grains, including wheat, barley, and rye, and is therefore a standard component of foods such as bread, pasta, pizza, and various cereals.

From a nutritional perspective, gluten provides no essential nutrients. However, its unique functional properties make it a highly valuable ingredient in baking, as it serves as a common additive in processed foods to improve texture, volume, and moisture retention. Despite its technological utility, gluten proteins can trigger a harmful immune response in individuals diagnosed with celiac disease.

Pathophysiology of Gluten Sensitivity and Clinical Indications

In genetically susceptible individuals—specifically those possessing human leukocyte antigen DQ2/DQ8 molecules on antigen-presenting cells—gluten triggers a T-cell mediated autoimmune enteropathy. This process ultimately results in inflammation, damage to the intestinal lining, and villous atrophy. Consequently, the dietary ingestion of gluten leads to nutrient malabsorption. The pathogenesis of this condition involves complex interactions between environmental, genetic, and immunologic factors. Furthermore, in cases of gluten ataxia, the body produces antibodies against gluten that mistakenly attack the cerebellum—the part of the brain responsible for motor control, balance, and muscle tone—resulting in ataxia.

Functional Roles of Gluten

Beyond its role in food technology, gluten supports germination and seedling development within the grain itself. It adds protein, texture, and flavor to food products, while also acting as a binding agent that holds processed foods together and gives them shape. Whole grains containing gluten can even help regulate blood sugar and lower cholesterol levels. Furthermore, these grains serve as sources of fiber, antioxidants, magnesium, iron, folic acid, B vitamins, and vitamin E.

Clinical Indications for Estimation

Clinical evaluation for gluten sensitivity is indicated in the following scenarios:

• Celiac Disease

• Non-celiac gluten sensitivity/non-celiac wheat sensitivity (NCGS/NCWS)

• Cerebellar Ataxia

• Dermatitis Herpetiformis

• Type 1 Diabetes

• Unexplained weight loss

• Malabsorption

• Persistent or unexplained gastrointestinal symptoms, such as chronic abdominal pain, bloating, and chronic diarrhea

• Unexplained iron deficiency anaemia

• Unexplained elevated liver enzymes

• Delayed puberty

Dermatitis Herpetiformis: Diagnosis and Management

Dermatitis herpetiformis (DH) is a cutaneous manifestation of gluten-sensitive enteropathy (celiac disease) and is often described as “celiac disease of the skin”. Patients diagnosed with DH typically possess serum IgA antibodies against both tissue transglutaminase and epidermal transglutaminase. If a patient’s tests indicate a high risk for celiac disease, clinical procedures such as an endoscopy—where a biopsy from the intestine is submitted for histological examination—are often ordered. Capsule endoscopy, which utilizes a camera inside a vitamin-sized capsule to take thousands of pictures of the GI tract, may be used when an examination of the entire small intestine is required.

Laboratory Diagnostics: Sample Collection and Testing Methods

For accurate blood sample collection, a fasting sample is preferred. Serum is required, involving the collection of 2 to 3 ml of blood via venipuncture transferred into a plain tube with a red cap. Samples should be stored at 2 to 8°C. Samples that are found to be icteric, hemorrhagic, or grossly lipemic cannot be accepted, nor can food samples.

Methods of Estimation

The following table outlines the methods and purposes of gluten-related testing:

Anti-Gliadin Antibodies (AGA): IgA and IgG Uses

IgA is generally more useful in detecting celiac disease because it is produced in the small intestine, the site where gluten causes inflammation and irritation in sensitive individuals. While IgG levels are less specific to celiac disease, they remain useful in diagnosing autoimmune problems, particularly in patients who are deficient in IgA. It is crucial to remember that while IgA is more sensitive for the detection of celiac disease, the IgG test is more useful for those with IgA deficiency.

For Non-Medicos: Understanding Anti-tTG and Test Limitations

Anti-tissue transglutaminase (Anti-tTG) antibodies are highly useful for diagnosing celiac disease. These antibodies are produced by the immune system as a mistaken reaction to gluten, wherein the immune system attacks the tissue transglutaminase enzyme in the small intestine and other tissues. An anti-tTG blood test measures these levels; elevated levels indicate an immune response to gluten.

Interpretation of Anti-tissue Transglutaminase Antibodies

Interpretation of Anti-Gliadin Antibodies

Limitations and Clinical Utility

There are specific limitations to these tests: in cases of extremely low total IgA values, one cannot rely on the results of Gliadin antibodies. Generally, the sensitivity and specificity of these tests hover around 90%. Clinically, these tests are utilized to manage and diagnose celiac disease and to determine if a gluten-free diet is essential. If such a diet is necessary, testing is used to monitor the introduction of the diet and its efficacy. Finally, testing is applied to ensure the accuracy of gluten-free food labelling and to prevent cross-contamination during food production.

References:

• Catassi, C., Verdu, E. F., Bai, J. C., et al. (2022). Coeliac disease. Lancet, 399(10344), 2413–2426. Cited by: 9

• Lebwohl, B., Ludvigsson, J. F., & Green, P. H. R. (2015). Celiac disease and non-celiac gluten sensitivity. BMJ, 351, h4347. Cited by: 455

• Levescot, A., Malamut, G., & Cerf-Bensussan, N. (2022). Immunopathogenesis and environmental triggers in coeliac disease. Gut, 71(11), 2337–2349. Cited by: 116

• Pelkowski, T. D., & Viera, A. J. (2014). Celiac disease: Diagnosis and management. American Family Physician, 89(2), 99–105. Cited by: 115

• Rubio-Tapia, A., Hill, I. D., Semrad, C., et al. (2023). American College of Gastroenterology guidelines update: Diagnosis and management of celiac disease. The American Journal of Gastroenterology, 118(1), 59–76.

• Sharma, N., Bhatia, S., Chunduri, V., et al. (2020). Pathogenesis of celiac disease and other gluten related disorders in wheat and strategies for mitigating them. Frontiers in Nutrition, 7, 6. Cited by: 283

• Gatti, S., Rubio-Tapia, A., Makharia, G., et al. (2024). Patient and community health global burden in a world with more celiac disease. Gastroenterology, 167(1), 23–33.

• Ludvigsson, J. F., Yao, J., Lebwohl, B., et al. (2025). Coeliac disease: Complications and comorbidities. Nature Reviews Gastroenterology & Hepatology, 22(3), 252–264.

• Abadie, V., Han, A., Jabri, B., et al. (2024). New insights on genes, gluten and immunopathogenesis of celiac disease. Gastroenterology, 167(1), 4–22.

• Mirza, H. A., & Baban, A. (2025). Dermatitis herpetiformis. StatPearls. Cited by: 20

• Fontana, G., & et al. (2025). Intestinal celiac disease-related autoantibodies. Frontiers in Immunology, 16, 1567416. Cited by: 4

• Syage, J., Ramos, A., Loskutov, V., et al. (2023). Dynamics of serologic change to gluten in celiac disease patients. Nutrients, 15(24), 5083. Cited by: 8

• Arnold, M. J. (2024). Diagnosis and management of celiac disease: Guidelines from the American College of Gastroenterology. American Family Physician, 109(1), 92–93. Cited by: 1

FAQ’s:

• What is gluten composed of?
  Gluten is a conglomerate of gliadin and glutenin proteins, primarily found in wheat.

• Where is gluten commonly found?
  It is found in grains like wheat, barley, rye, bread, pasta, pizza, and cereals.

• Why is gluten added to food?
  It improves texture, volume, and moisture retention while acting as a functional binding agent.

• What causes gluten sensitivity?
  Genetics and immune responses to gluten trigger damage to the intestinal lining in susceptible individuals.

• What is gluten ataxia?
  It occurs when gluten antibodies mistakenly attack the cerebellum, resulting in balance and motor control issues.

• Which conditions require gluten testing?
  Indications include celiac disease, dermatitis herpetiformis, unexplained weight loss, and chronic gastrointestinal symptoms.

• What is dermatitis herpetiformis?
  It is a cutaneous manifestation of celiac disease, often described as “celiac disease of the skin”.

• How is gluten sensitivity diagnosed?
  Diagnosis involves serological testing, such as Anti-tTG and Anti-Gliadin antibodies, and sometimes intestinal biopsy.

• Are fasting blood samples required?
  Yes, a fasting blood sample collected via venipuncture is preferred for accurate gluten sensitivity testing.

• Why monitor with lab tests?
  Testing helps diagnose celiac disease, verify diet compliance, and prevent cross-contamination in food production.

Related Tests 

• Gliadin Antibodies (AGA)