Celiac disease (CD) is a chronic intestinal autoimmune disease caused by intolerance to gluten, which are various proteins found in wheat and in other grains such as barley, and rye. 

Upon exposure to ingested gluten, an abnormal immune response may lead to the production of several different autoantibodies that can affect a number of different organs. In the small bowel, this causes an inflammatory reaction (Pic. 1), which damages the mucosal lining of the intestine and may lead to structural changes, such as shortening of the villi and even flattening of the folds in the wall of the small intestine (Pic. 2). This affects the absorption of nutrients, frequently leading to anaemia (decreased amounts of hemoglobin in blood). 

The disorder has a multifactorial etiology (many causative factors are involved in varying proportions) in which the triggering environmental factor, the gluten, and the main genetic factors, Human Leukocyte Antigen (cellular proteins that can trigger an immune system response) HLA-DQA1 and HLA-DQB1, are well known. 

Diagnosis is typically made by a combination of blood antibody tests and intestinal biopsies, helped by specific genetic testing. Celiac disease diagnosis can be established by serological tests, searching for anti-tissue transglutaminase (anti-TG2) and anti-endomysium (EMA) auto-antibodies (which are both serological markers for an active gluten-sensitive enteropathy), but confirmation of the intestinal damage relies on the small bowel biopsy and histological analysis. Making the diagnosis is not always straightforward. Frequently, the autoantibodies in the blood are negative and many people have only minor intestinal changes with normal villi. 

Celiac disease may present with typical symptoms such as diarrhea, steatorrhea (voluminous, fatty and foul-smelling stool), weight loss, and growth failure or non-typical symptoms not involving the gastrointestinal tract. The classic presentation of celiac disease is more common in young children, consisting primarily of gastrointestinal symptoms. In adults, the presentation of celiac disease is often more subtle and can be mistaken for irritable bowel syndrome. Some patients lack any evident gastrointestinal symptoms and instead present with nutritional deficiencies (most commonly iron deficiency) or extra-intestinal symptoms, or are asymptomatic.

A life-long gluten-free diet is the only available and effective therapy, which leads to normalization of histological and serological parameters and to complete remission of all clinical signs.

Symptoms

Fully developed symptoms such as malabsorption, steatorrhea and anemia are usually only seen in infants and young children. Adults more frequently present with atypic and less pronounced symptoms, commonly extraintestinal (affecting other systems than the gastrointestinal tract) or mimicking common issues such as dyspepsia (abdominal dyscomfort or pain) or irritable bowel syndrome.

Gastrointestinal symptoms

The diarrhea that is characteristic of coeliac disease is (chronic) pale, voluminous, and abnormally malodorous. Abdominal pain and cramping, bloatedness with abdominal distension (thought to be due to fermentative production of bowel gas), and mouth ulcers may be present. As the bowel becomes more damaged, a degree of lactose intolerance (means the body cannot easily digest lactose, a type of natural sugar found in milk and dairy products) may develop. 

Coeliac disease leads to an increased risk of both adenocarcinoma (a malignant tumour originating in glandular tissue) and lymphoma (a tumour composed of lymphocytes), termed enteropathy-associated T-cell lymphoma, or EATL, of the small bowel. This risk is also higher in first-degree relatives such as siblings, parents, and children. Whether or not a gluten-free diet brings this risk back to baseline is not clear. 

Long-standing and untreated disease may lead to other complications, such as ulcerative jejunitis (ulcer formation of the small bowel) and stricturing (narrowing as a result of scarring with obstruction of the bowel). 

Malabsorption-related symptoms

The changes in the bowel make it less able to absorb nutrients, minerals, and the fat-soluble vitamins A, D, E, and K. 

  • The inability to absorb carbohydrates and fats may cause weight loss (or failure to thrive/stunted growth in children) and fatigue or lack of energy.
  • Anaemia may develop in several ways: iron (Fe)malabsorption may cause iron deficiency anaemia, and folic acid and vitamin B12 malabsorption may give rise to megaloblastic anaemia (anemia caused by vitamin B12 deficiency).
  • Calcium (Ca) and vitamin D malabsorption may cause osteopenia (decreased mineral content of the bone) or osteoporosis (bone weakening and risk of fragility fractures).
  • Selenium (Se) malabsorption in coeliac disease, combined with low selenium content in many gluten-free foods, confers a risk of selenium deficiency. 
  • Copper (Cu) and zinc (Zn) deficiencies have also been associated with coeliac disease. 
  • A small proportion have abnormal coagulation due to vitamin K deficiency and are slightly at risk for abnormal bleeding.

Extraintestinal symptoms

Coeliac disease has been linked with a number of conditions. In many cases, it is unclear whether the gluten-induced bowel disease is a causative factor or whether these conditions share a common predisposition

  • IgA (immunoglobulin A) deficiency leads to an increased risk of infections.
  • Dermatitis herpetiformis (chronic blistering skin condition, characterised by blisters filled with a watery fluid), an itchy cutaneous condition (Pic. 3), features small-bowel changes identical to those in coeliac disease, and may respond to gluten withdrawal even if no gastrointestinal symptoms are present.
  • Growth failure and/or pubertal delay in later childhood can occur even without obvious bowel symptoms or severe malnutrition. Evaluation of growth failure often includes coeliac screening. 
  • Pregnancy complications can occur in case of coeliac disease as an intercurrent disease in pregnancy, with significant complications including miscarriage, intrauterine growth restriction, low birthweight and preterm birth.
  • Hyposplenism (a small and underactive spleen) occurs in about a third of cases and may predispose to infection given the role of the spleen in protecting against bacteria. Abnormal liver function tests (randomly detected on blood tests) may be seen. 
It is also possible to have coeliac disease without any symptoms whatsoever.

Associated diseases

  • type I diabetes
  • thyroid diseases (Grave’s disease, Hashimoto’s thyroiditis)
  • dermatitis herpetiformis
  • alopecia areata (a condition in which hair is lost from some or all areas of the body)
  • Sjogren’s syndrome (a long-term autoimmune disease in which the exocrine glands of the body are affected)
  • systemic lupus erythematosus (an autoimmune disease in which the body's immune system mistakenly attacks healthy tissue in many parts of the body)
  • juvenile idiopathic arthritis (the most common chronic rheumatologic disease in children and is one of the most common chronic diseases of childhood )
  • autoimmune hepatitis (liver inflammation)
  • psoriasis (a long-lasting autoimmune disease which is characterized by patches of abnormal skin)
  • sarcoidosis (a disease involving abnormal collections of inflammatory cells that form lumps known as granulomas)
  • thromboembolic phenomena (formation in a blood vessel of a clot (thrombus) that breaks loose and is carried by the blood stream to plug another vessel)
  • anaemia
  • growth failure
  • delayed puberty
Complications

Malignant tumours

Coeliac disease is associated with an increased risk of malignancy, not only of intestinal lymphoma, but also of small intestinal adenocarcinoma, which is 82 times more common in patients with celiac disease than in the normal population. Enteropathy-associated T-cell lymphoma (EATL) is a very rare peripheral T-cell lymphoma which is mostly associated with celiac disease.
Complications during pregnancy 

CD can induce malabsorption and deficiencies of micronutrients such as iron, folic acid and vitamin K, which are essential for organogenesis. The number of pregnancies ended in a miscarriage in celiac women has been observed to be almost twice that of healthy women, although the association in question is not statistically significant. In general, a larger number of complications have been observed in celiac women full term pregnancies compared to healthy women. In particular, the likelihood of having at least one complication during pregnancy has been estimated to be at least four times higher in celiac women than in healthy women. Moreover, a significant correlation has emerged for all the disorders under consideration (threatened abortion, gestational hypertension, placenta abruption, severe anaemia, uterine hyperkinesia, intrauterine growth restriction) and celiac disease. 

Risk factors

As for other autoimmune diseases, CD occurs more often in female than in male subjects with a gender ratio of about 2:1. 
Furthermore, gluten intolerance is more frequent in at-risk groups, such as first-degree relatives of patients as well as individuals with specific genetic syndromes (Down, Turner, Williams) or autoimmune diseases, mainly type 1 diabetes, thyroiditis (an inflammation of thyroid gland) and multiple sclerosis (a disease in which the myelin sheaths, the insulating covers of nerve cells in the brain and spinal cord are damaged).

Prevention

At present, the only effective treatment is a lifelong gluten-free diet. No medication exists that would prevent organ damage or prevent the body’s immune system from attacking the gut when gluten is ingested. Strict adherence to the diet allows the intestines to heal, leading to resolution of all symptoms in most cases and, depending on how early the diet is initiated, can also eliminate the increased risk of osteoporosis and intestinal cancer. The diet can be cumbersome; failure to comply with the diet may cause relapse (a recurrence of a past condition).

Dietitian input is generally requested to ensure the person is aware which foods contain gluten, which foods are safe, and how to have a balanced diet despite the limitations. In many countries, gluten-free products are available on prescription and may be reimbursed by health insurance plans. Gluten-free products are usually more expensive and harder to find than common gluten-containing foods. 

Female fertility

Malnutrition and its derived symptoms most commonly present in undiagnosed females with celiac disease. This symptom can directly compromise the potential and ability to conceive due to a negative energy balance and the decreased ability to maintain fat storage in afflicted females. Those with undiagnosed celiac disease and who do not follow a gluten-free diet may intensify unfavorable conditions for conception within the body and, more specifically, within the reproductive system. 

Due to celiac disease, women have deficiency of folic acid, iron, zinc and selenium, which is neccassary for a healthy reproductive life. All of them are essential for hormone production, and with lower levels of hormones, the ability of ovulation is decreased. Without ovulation, it is not possible to concieve a child.

Also women with celiac disease may start their periiods later and have earlier menopause, which leads to shorter period of fertility.

Male fertility

Men also suffer from infertility stemming from undiagnosed celiac disease. Affected males show a phenomenon of tissue resistance (insensitivity) to androgens (especially testosterone), which are neccessary for sperm development. The increased levels of follicle-stimulating hormone (FSH) and prolactin, which control the levels of androgens and thus also the sperm production, may indicate an imbalance at hypothalamus-pituitary (the highest regulatory centers of endocrine functions) level. Hypogonadism (diminished functional activity of the gonads—the testes in males) is a known factor in male infertility and has been found in 7% of celiac males in one survey.

Depending on the extent of the celiac disease at the time of diagnosis and also extent of complications and diet complication, the prognosis may vary. However, the prognosis is generally regarded as good. People with celiac disease are at higher risk of mortality than the general population. Although people with celiac disease had an increased risk of gastrointestinal and lymphoproliferative malignancies compared with the general population, it has been shown that they are in a lower risk of breast or lung cancer. The presence of gastrointestinal malignancies is associated with a particularly poor prognosis among patients with celiac disease.

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Sources

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