What is the role of thyroid hormones in the human body?

Question

Hi doctor,

I am a 28-year-old female. I want to know the role of thyroid hormones, such as T3 (triiodothyronine) and T4 (thyroxine) in the body. How do these hormones contribute to maintaining optimal health, and what happens when their levels get imbalanced? What is the cause behind hypothyroidism and hyperthyroidism? May I know the importance of thyroid glands in getting conceived? When having a thyroid disorder, what are the available treatment options? How is the appropriate treatment determined, and what lifestyle changes can individuals do to support thyroid health? Are there any preventive measures and lifestyle practices that can help maintain healthy thyroid function? Please help.

Thank you.

Answer 1

Hi,

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I really appreciate your keen interest in thyroid function. However, it is a wide topic for discussion.

Graves disease (diffuse toxic goiter), the most common form of overt hyperthyroidism, is an autoimmune condition, in which autoantibodies are directed against the thyroid-stimulating hormone (TSH) receptor.

Treatment for hyperthyroidism can be based on the symptoms. Treatment of hyperthyroidism and thyrotoxicosis includes symptom relief, while hyperthyroidism also requires anti-thyroid pharmacotherapy, radioactive iodine-131 (131I) therapy, or thyroidectomy. However, antithyroid medications are not effective in thyrotoxicosis (a clinical state where there is an inappropriately high level of circulating thyroid hormones), in which scintigraphy (a procedure that produces pictures of structures inside the body) shows low uptake of iodine-123 (123I), as in patients with subacute thyroiditis (an immune reaction of the thyroid gland that often follows an upper respiratory infection). These cases are a result of a release of preformed thyroid hormone.

A thyroid storm is a rare and potentially fatal complication of hyperthyroidism. It typically occurs in patients with untreated or partially treated thyrotoxicosis who experience a precipitating event such as surgery, infection, or trauma.

Elevation of free thyroxine (T4) and low to undetectable thyroid-stimulating hormone (TSH) levels are diagnostic of thyrotoxicosis; in earlier stages, triiodothyronine (T3) rise precedes T4 rise.

However, in the case of hypothyroidism, primary hypothyroidism is virtually the only disease that is characterized by sustained rises in TSH (thyroid stimulating hormone) levels. As the TSH level increases early in the disease, conversion of T4 to T3 also increases, maintaining T3 levels. In early hypothyroidism, TSH levels are elevated, T4 levels are normal to low, and T3 levels are normal. Given this early protection of the T3 level, routine checking of T3 is not recommended if one suspects that a patient is hypothyroid. Drawing a reverse T3 is also not recommended as a routine part of the hypothyroidism workup.

For the treatment of hypothyroidism, thyroid hormone is administered to supplement or replace endogenous production. In general, hypothyroidism can be adequately treated with a constant daily dose of levothyroxine (LT4).

I hope this information helps provide some insight into your symptoms.

Please do not hesitate to reach out if you have any further questions or concerns.

Thank you.