How the low or high levels of TSH affects body?

How the low or high levels of TSH affects body?

What is TSH?

TSH stands for “Thyroid stimulating hormone”. TSH is also known as “thyrotropin”. Thyroid stimulating hormone controls the functioning of the thyroid.

How TSH is produced?

TSH is produced by the pituitary gland in the brain which is later released into the bloodstream. Then the thyroid stimulating hormone binds to the receptor of the thyroid gland and promotes the production of the following hormones:

  • Triiodothyronine (T3)
  • Thyroxine (T4)

Both hormones have a negative effect on the pituitary gland. If the levels of these hormones are too high then, the production of thyroid stimulating hormone is stopped. It also turns off the production of “thyrotropin-releasing hormone”. Thyrotropin-releasing hormone induces the production of “TSH” or Thyrotropin”. Both hormones are helpful in maintaining body functions.

How the production of thyroid hormones is regulated?

Triiodothyronine is the active form of thyroxin. 20% triiodothyronine is directly secreted into the bloodstream by the thyroid gland while 80% is produced by the conversion of thyroxine into triiodothyronine. This activation of thyroid hormones is controlled by the liver and kidney which is performed by the enzymes called deiodinases. Deiodinases convert thyroxine into triiodothyronine.

The mechanism of Feedback inhibition maintains the level of T3 in the body. The high levels of thyroid hormones thyroxine and triiodothyronine cause the inhibition of the “thyrotropin-releasing hormone” production. In this way, the production of thyroid hormones is regulated.

How the level of TSH can be tested?

The level of thyroid stimulating hormone can be found by the TSH test. TSH test is the blood test used to measure the amount of thyroid stimulating hormone in the body. During this test, blood samples are taken from the vein. This test usually takes only 5 minutes. If the TSH test reports are abnormal then others test is also performed to determine the root cause of the problem. Additional test performed are the following:

  • T3 tests
  • T4 tests
  • Tests to diagnose Hashimoto’s thyroiditis disease
  • Tests to diagnose Graves’s disease

The normal level of thyroid hormones:

The normal level of thyroid hormones in adults is the following:

Hormone Normal Range unit
TSH 0.4-4.0 mU/L
T4 9.0-25.0 pmol/L
T3  3.5-7.8 pmol/L

How high level of TSH affects the body?

Blood tests are performed to check the level of TSH in the body. High level of TSH indicates the under activity of the thyroid gland. Underactivity of thyroid means that a low level of the thyroid is present in the body and to compensate that deficiency more thyroid stimulating hormone is produced.

This condition is known as “hypothyroidism”. The symptoms of hypothyroidism are the following:

  • Increased heartbeat
  • Heart palpitations
  • Sweating
  • Increased appetite
  • Fatigue
  • Goiter (thyroid gland enlargement)
  • Weight gain

Causes of Hypothyroidism

Hypothyroidism can occur because of several reasons which are the following:

Hashimoto’s thyroiditis

It is an autoimmune disorder and can cause hypothyroidism. During this disorder, antibodies are produced against the thyroid and affect their ability to produce hormones.

Excessive treatment of hyperthyroidism

During hyperthyroidism is, patients are often treated with radioactive iodine. Excessive use of such medicines can affect the ability of thyroid gland to produce hormones. In this way, these patients can get hypothyroidism.

Thyroid surgery

Removal of thyroid can also low levels of thyroid hormones. In such cases, patients must take thyroid medicines throughout life.

Radiation therapy

Radiation used to treat cancers of the head and neck can affect your thyroid gland and may lead to hypothyroidism.

Excessive use of medicines 

Unnecessary use of medications can also cause hypothyroidism. For example, lithium is used to treat psychiatric disorders, but it can also lead to this condition. This medication should be used only after the recommendation of a doctor.

Radiation therapy

Radiation therapies are used to treat cancers of the head and neck. The use of radiations in these areas can affect the activity of thyroid gland and can cause hypothyroidism.

Treatment of hypothyroidism 

Medications are used to normalize the level of thyroid hormones. The normal level of TSH is very important for pregnant women to ensure the healthy development of babies. It can be treated by using the following:

  • Healthy diet
  • Thyroxine hormone extracts or supplements
  • Medications like levothyroxine

How low levels of TSH affects the body?

Low levels of thyroid stimulating hormones indicate high levels of thyroid hormones. This condition is known as “Hyperthyroidism”

Symptoms of hyperthyroidism are the following:

  • Unintentional weight loss
  • Increased appetite
  • Irregular heartbeat
  • Increased sensitivity to heat
  • Anxiety
  • Changes in the menstrual cycle
  • Fatigue
  • Tremors
  • A slightly enlarged thyroid gland

Causes of hyperthyroidism

Hyperthyroidism can be caused by the following reasons:

  • Graves’s disease

It is an autoimmune disease. During Graves’s disease immune system attack cells of the thyroid gland. As a result, thyroid gland starts to produce more thyroid hormones which cause hyperthyroidism. In some cases, patients of Grave’s disease develop reddish thickened skin which is called as “Graves’s dermopathy”. It is usually painless but can be painful in some cases. Graves’s disease can also can irregular heartbeat which can cause strokes and heart failure. It can also cause Graves’s ophthalmopathy. It can also increase the chances of osteoporosis

  • Plummer’s disease

This condition is also known as “toxic multinodular goiter”. During this condition, adenomas are developed and cause the production of more thyroid hormones. Adenoma is the part of the gland which forms noncancerous lumps and causes the enlargement of thyroid gland.

  • Thyroiditis

It is known as “inflammation of thyroid gland”. Inflammation can be caused by autoimmune diseases or pregnancy. During this condition, inflammation of the gland causes an excessive leakage of thyroid hormone stored in the thyroid gland. Some types of this disease are painful while others are painless.

Risk factors

Risk factors associated with hyperthyroidism are the following:

  • A family history of Grave’s disease
  • Chronic illnesses, like diabetes 1 or anemia

Treatment of Hyperthyroidism

Medicines are available to treat this condition. It can be treated using the following:

  • Radioactive iodine(orally) can be used to shrink the size of the thyroid gland
  • methimazole can be used to inhibit the excessive production of thyroid hormone.

Untreated condition:

If the conditions caused by low or high levels of TSH are not treated. It can cause the following health problems:

  • Goiter
  • Heart problems
  • Neuropathy
  • Myxedema
  • Infertility
  • Birth defects
  • Mental health issues



Hilary Jensen

Hilary is a Food Science and Nutrition graduate with specialization in diet planning and weight loss. She enjoys reading and writing on Food, Nutrition, Diet, Weight Loss, and General Health.

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