What are CD and DH?

What is celiac disease?

Celiac disease or gluten sensitive enteropathy, is an inflammatory condition of the small intestine, induced by gluten. It has diverse clinical manifestations that resemble a multi-systemic disorder rather than a primary intestinal disease. Originally considered a rare disease of childhood, celiac disease is however now recognized as a common condition that may be diagnosed at any age. Characteristics include a close linkage to specific HLA alleles (DQ2/DQ8) and dependence on an environmental factor, gluten.

What is gluten?

Gluten is the term for the storage proteins of wheat. The alcohol-soluble fraction, called gliadin, has been most studied, but most or all gluten proteins are likely to be toxic in celiac disease, along with similar proteins in barley (hordeins) and rye (secalins). While the proteins of barley and rye are not strictly gluten they are commonly included in the term. These proteins induce in the intestine, in a dose dependent fashion, an inflammatory process that results in villous atrophy. Withdrawal of gluten from the diet results in regression of the process. The inflammatory process results in disturbed intestinal function, especially malabsorption of nutrients.

Characteristics of celiac disease

It is unclear whether celiac disease is an autoimmune disease or an inflammatory condition with autoimmune aspects.   The clinical classification of celiac disease is based on the presence of gastrointestinal symptoms. Symptomatic, active or classical celiac disease refers to presentations with diarrhea, with or without malabsorption, whereas in asymptomatic or silent celiac disease gastrointestinal symptoms are lacking or not prominent even though extra-intestinal symptoms may be present. The majority of individuals with celiac disease are considered to have the silent form.

Significance of celiac disease

Symptomatic celiac disease is associated with considerable morbidity due to chronic gastrointestinal symptoms and malabsorption of nutrients, weight loss, metabolic bone disease, anemia and general debility. The significance of the disease in the majority of individuals with silent celiac disease is less clear. However, most patients with silent celiac disease have occult manifestations of the disease, including reduced bone density, iron or folate deficiency and associated autoimmune diseases that are frequently more clinically significant. Celiac disease results in an increased risk of the development of various malignancies including lymphoma at any site, not only the small intestine. There is also an increased mortality rate in celiac disease, exceeding that of the general population by a factor of 1.9 to 3.8. The increased mortality is mainly due to malignancies. The excess mortality is reduced after 1 to 5 years on a gluten free diet, demonstrating protection by the gluten-free diet.

Clinical presentation of celiac disease

Infants and young children present with diarrhea, abdominal distension and failure to thrive. However, vomiting, irritability, anorexia and constipation are also common. Older children often present with extra-intestinal manifestations, such as short stature, neurologic symptoms or anemia.

Diarrhea, the hallmark of intestinal diseases, occurs in less than 50% of adults with celiac disease. When present diarrhea reflects a more extensive involvement of the length of the small intestine. Celiac disease should be high in the differential diagnosis of any patient who complains of diarrhea. Other ways in which patients present include more vague intestinal symptoms that may get labeled as an irritable bowel syndrome, or with weight loss or abdominal pain. Many patients get the diagnosis of celiac disease after upper intestinal endoscopy performed for ulcer-like symptoms or esophageal reflux symptoms. At the endoscopy the features of celiac disease may be recognized by the endoscopist when the disease had not previously been suspected.  Other patients present having been assessed for iron deficiency anemia or osteoporosis. The diagnosis may be established because of non-gastrointestinal manifestations of the disease. These include dermatitis herpetiformis (DH), neurological symptoms such as peripheral neuropathy, ataxia, or epilepsy, frequently with occipital calcifications. Other, less common presentations include apthous stomatitis, arthritis, dental enamel defects, and abnormal liver chemistries. The diagnosis may be established through screening groups at an increased risk to develop celiac disease. These include first-degree relatives of patients with celiac disease, those with Type 1 diabetes, Down syndrome or chronic liver disease, most notably primary biliary cirrhosis.

What is dermatitis herpetiformis (DH)?

DH is an intensely itchy vesicular rash occurring anywhere on the body, especially on the extensor surfaces (knees and elbows) and the scalp. Patients tend to experience the rash in the same area, for example on their hands, in their scalp or on the buttocks. Virtually 100% of patients with DH have celiac disease, though the intestinal lesion is usually milder than most patients who have predominantly gastrointestinal complaints. The lesions of DH are very sensitive to even the ingestion of small amounts of gluten. Other dietary factors, for example iodine, may exacerbate the rash or prevent its healing. The rash is however dependant on the ingestion of gluten. While Dapsone will control the skin lesions of DH, a gluten-free diet allows Dapsone to be discontinued, healing of the intestine and reduction in the risk of the development of lymphoma that is increased in patients with DH.