Hashimoto’s disease is the most common thyroid disorder, in which there is lymphocytic infiltration of the thyroid gland that leads to the destruction of thyroid gland causing decreased production of thyroid hormone, clinically known as hypothyroidism; this is the reason Hashimoto’s thyroiditis is also known as chronic lymphocytic thyroiditis. This decreased production of thyroid hormone is the reason for manifestation of different signs and symptoms in the body. The most common clinical presentation of Hashimoto’s thyroiditis (HT) is the enlargement of thyroid gland known as goiter, but it may not be present in some of the patients. HT also shows an increased level of thyroid antibodies, thyroid peroxidase (TPO) and thyroglobulin (Tg), in the sera of patients with the disease. Research has shown that TPO is present in about 90% of all HT patients and Tg in about 80% of the patients.
The clinical manifestation of HT may be varied ranging from normal thyroid function to severe hypothyroidism. Initially, it may present with thyrotoxicosis for a short duration before gradually progressing to mild to moderate or severe hypothyroidism. Hashimoto’s disease presents with symptoms of hypothyroidism that are increased fatigue, sleepiness, weight gain and inability to lose weight, goiter, puffiness and paleness of face, muscle and joint pain, susceptibility to cold, constipation, hair loss or thinning of hair, dry/brittle hair, irregular periods, inability to get pregnant which sometimes lead to infertility, slow heart rate, mental problems such as inability to concentrate, fogginess, forgetfulness and it also may lead to depression. The patient of HT may present with one or more symptoms and should visit a doctor if one notices any of the symptoms.
Is Hashimoto’s Disease Inherited?
Genetics And Hashimoto’s Disease
In spite of high prevalence of Hashimoto’s disease, the etiology and pathogenesis of the disease is still unclear. It’s postulated to be a complex trigger of genetics and environmental factors. It is also interesting to know that people with Hashimoto’s thyroiditis are also susceptible to other autoimmune diseases such as type 1 diabetes, rheumatoid arthritis, multiple sclerosis, pernicious anemia, Addison’s disease and vitiligo to name a few.
Several genes have been associated with HT and the most common of them is the human leukocyte antigen (HLA) complex. The role of HLA complex is to help immune system differentiate between body’s own proteins and foreign proteins such as produced by various viruses and bacteria. The other genes that are related to Hashimoto’s disease are Cytotoxic T Lymphocyte Antigen-4 (CTLA-4) gene, Protein Tyrosine Phosphatase Nonreceptor-Type 22 (PTPN22) gene, Thyroglobulin (Tg) gene, Vitamin D Receptor (VDR) gene, cytokine genes and other immune related genes.
After numerous studies, it is still unclear whether Hashimoto’s disease is inherited or not because its etiology remains unclear, there are many genetic and environmental factors that are implicated in this disease. However, Hashimoto’s disease has been closely linked in females, family members, relatives and twins.
Hashimoto’s disease is more common in females than in males and after various studies it has been implicated that there might be defects in X chromosome that might play an important role in immunity thus leading to autoantibody production. Apart from genetics, environmental factors have also an important role to play in Hashimoto’s disease. The environmental factors that might trigger HT include infections such as hepatitis C infection and exposure to other viruses including parvovirus, herpes simplex virus, Epstein Barr virus, rubella and human T-lymphotropic virus; exposure to chemicals such as polychlorinated biphenyls or polyaromatic hydrocarbons;
Certain drugs such as interferons (used extensively in the treatment of chronic hepatitis), interleukins (used in the treatment of renal carcinoma and melanoma), lithium and amiodarone; excessive iodine intake; exposure to radiation (Chernobyl nuclear accident, atomic bombs in Hiroshima and Nagasaki, radiation treatment for blood cancer such as Hodgkin’s lymhoma); and also hormonal changes such as changes in hormones when a woman is pregnant. The studies are ongoing and we will be better able to understand the etiology and pathogenesis of Hashimoto’s disease with advanced research and further studies.