Is Hashimoto's an Autoimmune Disease?
Before we begin with the topic of Hashimoto’s disease one must be clear about an autoimmune disease. So how will you define an autoimmune disease?
In very simple words in autoimmune disease body attacks its own cells. This means that the immune system considers the body cells as a foreign body material and thus, mounts an immune attack against it; the auto-regulatory mechanism is disrupted. Moving on to our main topic that is Hashimoto’s disease an autoimmune disease?
Is Hashimoto's an Autoimmune Disease?
Yes, it is an autoimmune disease in which body attacks its own thyroid gland. There is marked lymphocytic infiltration of the thyroid glands. In later stages, there is atrophy of thyroid follicles and depletion of colloid associated with fibrosis of thyroid follicles. Atrophic thyroiditis is the end stage of this disorder where there is no chance of recovery.
Every autoimmune disease occurs in association with environmental and genetic factors. In this particular disease HLA- DR3, HLA-DR4 and DR5 are considered as a risk factor and polymorphism in any of these genes will lead to the disease. But besides these elements, the environmental factors also contribute to the development of the disease.
At times this autoimmune disease occurs in association with other autoimmune diseases like diabetes mellitus, in which body mounts an attack against beta cells of the pancreas, vitiligo, body mounts attacks against pigment cells of the skin, pernicious anemia in which immune attack is mounted against intrinsic factor which leads to decreased absorption of vitamin B12.
Autoimmunity is imparted against thyroid peroxidase and thyroglobulin. Few studies have proved that infection can even be the cause of Hashimoto's disease as it seen that Rubella syndrome is most commonly encountered in Hashimoto’s disease.
T-cells are mainly responsible for the destruction of thyroid follicles. CD8+ cells are primarily responsible. Thyroid cells have FAS death receptors on their surface, which are activated by T cells when they bind with these death receptors. Once the inflammatory process begins a cascade of events occurs, which lead to the destruction of the thyroid gland.
Clinical features include-
All the features of hypothyroidism are seen in this particular disorder which includes-
- Dry skin
- Intolerance to cold
- Weight gain
- Hair loss
- Impairment of memory and difficulty in learning
- Hoarse voice
The most important sign which helps in diagnosis is delayed tendon reflex relaxation.
- Carpel tunnel syndrome
- Puffiness around the eyes is commonly seen
- Peripheral edema
- Effusion in various cavities
- Carotene accumulation imparts a yellow color to the skin.
- Decreased nail growth and absence of lateral half of eyebrows.
- Fertility is reduced and galactorrhea is often a common complaint.
- When the fluid accumulates in middle ear usually patient comes with a complaint of conductive deafness.
Since neonatal hypothyroidism is frequently encountered these days screening is conducted to decrease the prevalence of neonatal hypothyroidism. Heel prick test is done and T4 and TSH levels are also monitored. The normal level of T4 should be maintained as there is a high chance of creationism in children which leads to mental retardation and decreased IQ. Early treatment can decrease the neurological abnormalities in further life. Thyroid hormone should be given to mother in an appropriate amount if she is pregnant so that there is no chance creationism in new-born.
The best way of diagnosing Hashimoto is by evaluation of TSH levels. If it is elevated which usually happens in hypothyroidism so as to increase the production of T4. If it is found to be elevated then check T4 level. If T4 level comes normal then it is a case of mild hypothyroidism. But when T4 comes low then it is considered an autoimmune disease.
Autoimmune antibodies against thyroid peroxidase may be found in blood. So proper analysis should be done, after analysis, levothyroxine should be given in apt amount.
Thyroid should be treated as early as possible else further complications may arise. The pregnant women and neonates are at high risk so mandatory screening should be done in this particular group of people. If correctly diagnosed and treated there are very few chances of complications.