Celiac Disease

Celiac Disease

Introduction

Celiac disease (CD), also known as celiac sprue, non-tropical sprue, and gluten sensitive enteropathy, is a multi symptom, multi system autoimmune disease. It causes an abnormal immune reaction to gluten and a resulting malabsorption of nutrients. What once was thought to be a rare childhood disorder is now known to be a common condition. It affects approximately 1% of individuals who are of European descent, and has been documented in North and South America, Europe, north Africa, south and west Asia, and Australia. As many as 3 million Americans may have the disease. Approximately 1 in 133 people have CD, but only 3% have been diagnosed. It is regularly misdiagnosed and underreported. (Maher, 2008)

CD was identified in the first century A.D. when a Greek Physician, Arataeus of Cappadocia, called it koilakos after koelia, which is the Greek word for abdomen. British physician Samuel Gee described it in 1887 as a chronic indigestion that especially affected children between the ages of one and five. Gluten was not identified as the causative factor until after WWII, when Dutch pediatrician Willem-Karel Dicke noticed that the death rate of children due to CD dropped from 35% to essentially zero during the war. He also noted that with the end of the conflict, and end of a resulting bread shortage, the rate immediately climbed back to pre war levels. (Jones, 2009)

Etiology

The cause of celiac disease is unknown. However, three things must be present for manifestation of the disease: a genetic disposition, a trigger factor and the presence of a diet including gluten. There seems to be a strong genetic link to specific human leukocyte antigens (HLA). HLAs normally bind to foreign antigens such as bacteria and viruses, and present them to T cells to initiate an immune response. Patients with CD have additional HLAs (HLA-DQ2 and HLA-DQ8), which bind to a protein called gliaden, a component of gluten found in wheat, rye and barley. People with celiac disease also have a higher than normal level of particular autoantibodies: anti-tissue transglutaminase antibodies (tTGA) and anti-endomysium antibodies (EMA). Many times, before the onset of symptoms, there is a precipitating factor such as surgery, pregnancy and childbirth, viral infection or severe emotional stress. Most importantly, for any symptoms or complications of the disease to occur, the individual must have a diet that includes gluten.(Alaedini, 2005) The onset of CD can happen at any age, and it is not gender specific, although more women than men are diagnosed. Other autoimmune diseases associated with an increased risk of CD are insulin-dependent Type 1 Diabetes Mellitus, Hashimoto's thyroiditis, lupus (SLE), Addison's disease, chronic active hepatitis, rheumatoid arthritis, Turner Syndrome, Sjögren's Syndrome, Raynaud's Syndrome, alopecia areata and scleroderma

Pathophysiology

As stated, the ingestion of gluten by an individual with CD stimulates the T cells to produce antibodies. These antibodies, in turn, attack the villi that line the small intestine. Millions of villi normally cover the small intestine like a shag carpet, but with CD, the villi are destroyed until the surface of the small intestine more closely resembles a worn tile floor with numerous ridges and crypts.(Kagnoff, 2007). The reduction or absence of villi in the intestine severely diminishes the intestine's ability to absorb nutrients including protein, carbohydrates, fats, vitamins and minerals. This may lead to several complications, including delayed puberty, anemia, diminished stature in children, and osteoporosis. (Hockenberry, 2009)

Signs and symptoms

Signs and symptoms of CD are varied, from asymptomatic to severe malnutrition. Most people with CD have complaints of intermittent diarrhea, abdominal pain, and bloating. Other less obvious signs include anemia, joint pain, stomach upset, muscle cramps, mouth sores, bone disorders, infertility, abnormal liver function and neuropathy. There may also be signs and symptoms related to malabsorption caused by the reduction in villi such as weight loss, diarrhea, foul smelling stools, and stunted growth in children. Some patients have no outward sign of the disease, but are found to have atrophy of the villi during unrelated endoscopies or biopsies. (Alaedini, 2005)

Diagnostics / Labs

There are several tests to diagnose or exclude CD. For testing accuracy, a person must follow a diet that contains gluten for at least 4 weeks prior to testing. Specific antibody tests are used for initial screening. They are anti-tissue transglutaminase antibody (tTG), anti-endomysial antibody (EMA), anti-deaminated gliadin peptide and total serum IgA. Anti-gliadin antibody is used for children under two because tTG and EMA antibodies are absent at that age. (Lurz, 2009) A positive antibody test cannot confirm a diagnosis of CD, but only suggest it. The next step is a small bowel biopsy. A positive biopsy is required to confirm the disease and to evaluate the amount of damage to the villi. However, biopsies can also yield a false negative result due to the patchy nature of the intestinal damage. A definitive diagnosis is only given with clinical improvements