Coeliac disease and gluten: symptoms, testing and a gluten-free diet

Coeliac disease is often missed, because its symptoms can look like other gut problems or may be absent ^{[1, 3]}. This article explains what coeliac disease is, who gets it, how it is found and how it is managed, using information from the NHS, the US National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and MedlinePlus.

1. Introduction

Coeliac disease is an autoimmune condition, which means the immune system attacks the body's own tissue. In coeliac disease the immune system reacts to gluten and damages the lining of the small intestine, so the body cannot absorb nutrients properly ^[1]. Gluten is a protein found in wheat, barley and rye ^{[1, 2, 3]}.

It is different from a wheat allergy and from gluten sensitivity, because only coeliac disease damages the small intestine ^[3]. NIDDK estimates that about 1 in 100 people worldwide have coeliac disease, and many of them have not been diagnosed ^[2]. The NHS says that at least 1 in 100 people in the UK are affected ^[1].

2. Causes and risk factors

The cause is not fully understood, but both genes and environment seem to play a part ^[1]. NIDDK states that a person must carry certain genes to develop the disease ^[2]. The NHS and NIDDK name these groups as having a higher risk ^{[1, 2]}:

• Close relatives, meaning parents, brothers, sisters and children, of someone with coeliac disease
• People with type 1 diabetes or autoimmune thyroid disease
• People with Down syndrome or Turner syndrome

It can develop at any age and is diagnosed more often in women than in men ^{[1, 2]}.

3. Signs and symptoms

Symptoms vary a lot and can come and go. The NHS and MedlinePlus list ^{[1, 3]}:

• Diarrhoea, stomach aches, bloating, wind, indigestion or constipation
• Tiredness and unintended weight loss
• An itchy, blistering skin rash called dermatitis herpetiformis
• Bone or joint pain, and mouth problems such as canker sores
• Slow growth and delayed puberty in children
• Nerve problems, and in some people, low mood or anxiety

MedlinePlus notes that symptoms can be mistaken for other conditions or can be absent ^[3]. The NHS says milder cases may be mistaken for irritable bowel syndrome ^[1].

4. Diagnosis and tests

The NHS says routine testing is not done in England, but it is usually recommended for people with symptoms or an increased risk, such as a family history. Close relatives of people with coeliac disease should be tested ^[1].

According to MedlinePlus, a provider reviews your history and examines you. Blood tests and a small intestine biopsy, in which tiny samples of the lining are taken, are the most common ways to diagnose it. The biopsy is usually taken during an upper endoscopy, a camera test through the mouth ^[3].

Ask your doctor before changing your diet.

5. Treatment and management

The main treatment is a gluten-free diet for life. MedlinePlus states that it can treat or prevent many symptoms and complications and, in most cases, allows the intestine to heal ^[3]. The NHS says the diet helps control symptoms and prevent long-term complications, and is recommended even for mild symptoms or when tests show coeliac disease without noticeable symptoms ^[1].

Practical points from the sources:

• Gluten is in pasta, cakes, breakfast cereals, most breads, some sauces and some ready meals. Most beers are made with barley ^[1].
• Oats do not contain gluten themselves, but can cause a reaction if they are produced alongside wheat, barley or rye. A small number of people react to pure oats ^[1].
• Gluten can also hide in items such as certain supplements, cosmetics and toothpaste, so read labels. If a label is unclear, the maker can supply an ingredient list ^[3].
• A registered dietitian can help plan a healthy, balanced gluten-free diet ^[3].

In rare cases, a person still has trouble absorbing nutrients despite a strict gluten-free diet. This is called refractory coeliac disease and needs specialist care ^[2].

6. Complications

Complications mainly affect people who keep eating gluten or who have not yet been diagnosed. The NHS lists ^[1]:

• Osteoporosis, which is weakening of the bones
• Iron-deficiency anaemia, and anaemia from low vitamin B12 or folate
• Less commonly, some cancers such as bowel cancer, and pregnancy problems such as low birth weight

NIDDK also mentions malnutrition, nerve problems and reproductive problems ^[2].

7. Special groups

Children may grow more slowly and may have delayed puberty ^[1]. Close relatives should ask about testing even without symptoms ^[1]. People with type 1 diabetes or thyroid disease should mention any digestive symptoms to their doctor, because these conditions are linked with coeliac disease ^{[1, 2]}.

8. When to see a doctor

The NHS says testing is usually recommended for people with symptoms or a higher risk ^[1]. See a doctor if you have long-lasting diarrhoea, bloating, tiredness, weight loss, an itchy blistering rash, or if a close relative has coeliac disease. Ask your doctor before starting a gluten-free diet on your own. If a child is growing slowly or has long-lasting tummy problems, speak to a doctor.

In an emergency, call your local emergency number (112 in India, 911 in the United States).

9. Conclusion

Coeliac disease is a long-term immune reaction to gluten that can affect the gut and the rest of the body. Blood tests and a biopsy confirm it, and a strict gluten-free diet planned with a dietitian is the main treatment. Complications such as anaemia and weak bones mainly affect people who keep eating gluten or have not been diagnosed.