All about Hypothyroidism (Part 3): What are the types of Hypothyroidism?
Updated: Mar 2
Types of Hypothyroidism
1. Juvenile /pediatric/ congenital / Transient hypothyroid
At birth, there are two forms of hypothyroidism.
Transient hypothyroidism is characterized by abnormal thyroid hormone levels during birth as a result of the mother’s thyroid medication or antibodies. It normally clears up on its own and does not require long-term therapy.
Congenital hypothyroidism is a condition that is present at birth and can be detected through neonatal screening. This type can lead to mental retardation if not treated.
Children’s hypothyroidism symptoms differ from those of adults. Each youngster may have a different set of symptoms–or none at all. The following are the most prevalent symptoms, organised by age:
Newborns – Jaundice (a yellowish hue to the skin), constipation, and diarrhoea are common among newborns.
Children – slow growth
Teenagers – delayed puberty
Acquired hypothyroid
Atrophy of thyroid gland; Antibody attack causes atrophic thyroiditis, a severe form of primary hypothyroidism in which the thyroid gland shrinks and shrivels.
Induced hypothyroid (Amiodarone induced)
Hypothyroidism is a potential side effect of Amiodarone, an antiarrhythmic drug.
Pregnancy induced/ maternal hypothyroid
Hypothyroidism in pregnant women is known as maternal hypothyroidism. It may offer risks not only to the mother, but also to the unborn, and needs appropriate treatment.
Another classification of Hypothyroidism is
Primary hypothyroid –
In this type, the thyroid gland is sufficiently activated. The thyroid gland, on the other hand, is unable to create enough thyroid hormones for the body to function properly. This indicates that the problem is caused by the thyroid gland.
Secondary Hypothyroidism
In this type, the pituitary gland does not stimulate the thyroid gland enough to create sufficient hormones. To put it another way, the issue is not with the thyroid gland.
Tertiary Hypothyroidism
In tertiary hypothyroidism, insufficient thyrotropin-releasing hormone (TRH) secretion from the hypothalamus results in insufficient TSH release, which leads to insufficient thyroid activation.
Iatrogenic hypothyroidism:
Patients under treatment for hyperthyroidism with Neo-mercazole may develop Hypothyroidism as an adverse effect.
What are the Causes and risk factors of Hypothyroidism?
The most frequent cause of hypothyroidism in children and teenagers is Hashimoto thyroiditis (also known as autoimmune hypothyroidism or chronic lymphocytic thyroiditis).
There is a female predominance, like with other autoimmune diseases (approximately 2:1). In 40-50 percent of patients, there is a family history of autoimmune hypothyroidism.
Autoimmune hypothyroidism can arise in the presence of other autoimmune diseases, the most frequent of which is Type 1 diabetes.
Addison’s illness, celiac disease, vitiligo, and systemic lupus erythematosus are all linked to it.
Autoimmune hypothyroidism is caused by chromosomal abnormalities.
Hypothyroidism is more common in children with Down’s and Turner syndromes, hence routine testing is recommended in these individuals. TSH levels may be evaluated in children with Down’s syndrome at birth, 12 months, and then annually following the first year of life.
After the age of four years, girls with Turner syndrome should have their TSH measured once a year.
In the differential diagnosis of acquired hypothyroidism, other diseases should be investigated. Iodine deficiency is the most prevalent cause of hypothyroidism worldwide, despite its rarity in the developed countries.
Hypothyroidism is caused by radioiodine therapy and surgical excision of the thyroid gland after treatment for Graves’ disease or thyroid cancer.
Children are at risk of hypothyroidism after receiving radiation to the neck for various disorders (most commonly Hodgkin’s lymphoma or prior to a bone marrow transplant).
Anti-thyroid medicines (propylthiouracil or methimazole), lithium, amiodarone, and anti-epileptic medications all affect thyroid function.
Cassava, broccoli, sweet potato, soybeans, and certain industrial chemicals, such as perchlorate and polychlorinated biphenyls, are all goitrogens.
Secondary or central hypothyroidism can be caused by a tumour, surgery, or trauma. Low TSH and T4 concentrations can be caused by acute or chronic sickness, and this might be misconstrued for central hypothyroidism.
This non-thyroidal ailment (often referred to as “euthyroid sick” condition) does not require treatment, and thyroid function returns to normal as the disease process progresses.
Thyroid hormone binds to thyroid hormone binding globulin and circulates in the bloodstream (TBG). Low T4 with normal serum TSH and free T4 levels is the result of familial TBG deficiency, which is inherited in an X-linked pattern (depending on the assay).