Autoimmune diseases are a diverse group of illnesses caused by misdirected immune system activity. Normally, the immune system's sophisticated seek-and-destroy activities target only invading organisms. With autoimmune diseases, the immune system mistakenly attacks various tissues within the body causing damage, cell death and scarring. Several autoimmune diseases can cause weight loss, either by direct involvement of the gastrointestinal system or via changes in the body's metabolism. Effective control of the autoimmune disease often eliminates or minimizes unintentional weight loss.
Graves' Disease
Graves' disease is an autoimmune disorder affecting the thyroid gland. The immune system produces antibodies that attach to the thyroid, stimulating excessive production of the thyroid hormones. According to a report in the August 2005 "American Family Physician," Graves' disease is the leading cause of an overactive thyroid, also known as hyperthyroidism. Elevated levels of the thyroid hormones increase the activity of cells throughout the body. This increase in metabolic rate commonly causes weight loss. The National Institutes of Health reports Graves' disease is five to 10 times more prevalent in women than in men. The disease most commonly affects adults under age 40.
Autoimmune Pernicious Anemia
Autoimmune pernicious anemia is characterized by immune system destruction of cells in the stomach that produce the chemical intrinsic factor. An intrinsic factor deficiency results. The absorption of dietary vitamin B12 requires the presence of intrinsic factor. As noted by the National Heart, Lung and Blood Institute, vitamin B12 is required for the production of red blood cells. Without sufficient intrinsic factor the body lacks vitamin B12, and this deficiency leads to anemia. The University of Virginia Health System reports common symptoms of pernicious anemia include decreased appetite, nausea, diarrhea and weight loss.
Scleroderma
Scleroderma is an autoimmune disease in which the immune system attacks and stimulates cells that lay down scar tissue. The primary sites of excessive scar tissue formation distinguish the various forms of this disease. The National Institute of Arthritis and Musculoskeletal and Skin Diseases points out that although skin involvement is the hallmark of scleroderma, other organs including the lungs, heart, kidneys and those of the gastrointestinal system are also frequently affected with this disease. Damage in the esophagus, stomach and intestines can cause eating and digestion difficulties. "The Merck Manual for Healthcare Professionals" reports narrowing of the esophagus due to scar tissue is a common symptom of scleroderma. Such narrowing can cause mild to severe swallowing difficulties. Intestinal damage may cause impaired absorption of dietary nutrients. Weight loss is a common symptom among people with scleroderma with gastrointestinal involvement.
References
- National Endocrine and Metabolic Diseases Information Service: Graves' Disease
- University of Maryland Medical Center: Graves Disease
- American Family Physician: Hyperthyroidism Diagnosis and Treatment
- National Heart, Lung and Blood Institute: What is Pernicious Anemia?
- University of Virginia Health System: Megaloblastic (Pernicious) Anemia
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