May 16, 2022

What is TSH?

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The thyroid is a butterfly-shaped gland located in the neck. This gland is important for the production of certain hormones that control the body’s metabolism. With a thyroid disorder, the gland can either work too quickly or too slowly, which can affect many different body systems and cause a number of unpleasant symptoms. With Homed-IQ’s Thyroid Blood Test you measure the amount of TSH and other key thyroid hormones in your blood, so you know whether your thyroid is functioning properly or not.

What is TSH?

TSH stands for Thyroid Stimulating Hormone and is a hormone produced by the pituitary gland. TSH directs the thyroid gland to produce thyroid hormones. These hormones are then brought into our body cells via the bloodstream to moderate metabolism. Thyroid hormones are important in cell metabolism and thus influence our total physical and mental well-being.

When thyroid hormone levels are high, the production of TSH decreases, and when thyroid hormones are low the production of TSH increases. 

What does TSH do?

TSH stimulates the thyroid gland to produce the thyroid hormones T4 and T3. These hormones have an important function in your body. For example, they influence the metabolism of organs and cells. TSH also has an effect on development, growth and energy levels. A TSH value that is too high causes the body’s metabolism to slow down (hypothyroidism), and too low a TSH value causes the metabolism to run too fast (hyperthyroidism). In general, T4 and T3 have an effect on the heart, muscles, bones, nervous system, intestines and oxygen consumption, including on:

  • Heart rhythm
  • Fat Burning
  • Protein breakdown
  • Bone growth
  • Brain development
  • Absorption of sugars
  • Oxygen consumption

What is the difference between TSH and T3/T4?

While TSH and T3/T4 are related to thyroid function, they have several differences in function. The production of TSH takes place in the pituitary gland, which functions as a hormone-producing gland in the brain. TSH ensures the production of the optimal amount of T4 and T3. T3 regulates your energy level and functions as a thermostat in the body. Free T4 is a hormone that ensures that processes in the body run quickly enough.

What are normal TSH levels?

A normal TSH value is within the reference range (Wiersinga, Dutch Journal of Medicine, 2003). This is as follows:

  • Reference interval normal TSH value: 0.4 – 4.0 mE/l

If a thyroid test shows that the value is between these numbers, then this means you have a normal TSH value.

What does a high TSH value mean?

A TSH value that is too high means that the pituitary gland produces too much TSH, which means that there are too little thyroid hormones in the body. The medical term for this is hypothyroidism, or underactive thyroid.

What does a low TSH level mean?

A low value means that the pituitary gland produces too little TSH, causing an overactive thyroid gland. The medical term for this is hyperthyroidism.

What are the causes of an elevated TSH level?

An important cause of elevated TSH or underactive thyroid is Hashimoto’s disease. In this disease, the immune system is confused and attacks the thyroid gland. The thyroid then makes lower amounts of hormones and eventually even stops. In addition to this autoimmune disease, there are a number of other causes for high TSH values:

  • Problems with the immune system
  • Inflamed thyroid gland after childbirth
  • Thyroid surgery
  • Radiation of the neck
  • Medicines containing iodine
  • Medicines containing lithium
  • Treatment with radioactive iodine

You are more likely to develop an underactive thyroid if this condition runs in your family. The risk also increases after childbirth, especially in the first year after. Overall, women and elderly people are more likely to develop a thyroid condition. 

What are the causes of a low TSH level?

A TSH value that is too low causes the thyroid gland to work too quickly, and can be caused by various reasons. The most well-known cause is Graves’ disease. This autoimmune disease causes the body to develop antibodies against the thyroid gland. This gland responds by producing more hormones. Other causes also include (Isala, 2022):

  • Goiter: thyroid gland grows with increasing production of thyroid hormone
  • Quervain’s disease: painful inflammation of the thyroid gland (non-chronic)
  • Thyroiditis: non-painful inflammation of the thyroid gland

The symptoms of a TSH value that is too high

Several health consequences are possible with a TSH value that is too high, causing an underactive thyroid (Thuisarts, 2019):

  • Getting cold quickly
  • Weight gain
  • Fatigue
  • Slower heart rate
  • Constipation
  • Hair loss
  • Pale skin
  • Thick eyelids
  • Thyroid swelling
  • Voice change
  • Irregular periods

The symptoms of a TSH value that is too low

With a TSH that is too low or an overactive thyroid gland, there are different symptoms:

  • Palpitations
  • Trembling
  • Sweating
  • Anxiety
  • Fatigue
  • Intestinal problems
  • Weight loss
  • Warm skin
  • Bulging eyes
  • Blurred vision
  • Irregular periods
  • Enlarged thyroid

Are there any diseases related to TSH?

There are several diseases related to TSH, such as Hashimoto’s disease, Graves’ disease, goiter, Quervain’s disease, and thyroiditis (Nederlands Huisartsen Genootschap).

TSH testing

TSH testing with a Homed-IQ home test is useful if you want to know whether your thyroid values are normal. Using a home test, you can measure your TSH levels without a visit to a doctor. This is very easy, with blood collection involving only a simple finger prick.. Your blood sample will then be analyzed by a certified laboratory. The thyroid test not only provides insight into the value of the thyroid stimulating hormone TSH, but also gives you the values of FT3 (free thyronine) and FT4 (free thyroxine).

What can I do if my TSH value is too high or too low?

An overactive thyroid can be treated in different ways. Your GP  can prescribe medication, but it is also possible to undergo surgery or receive treatment with radioactive iodine. An underactive thyroid can be treated with drugs that contain thyroid hormones. The effect is noticeable after a few weeks, with most symptoms completely disappearing. 

About the author

Lauren Dobischok

Lauren is a health scientist and science communicator currently living in the Netherlands. Originally from Canada, she completed a Research Master’s in Health Sciences at the Netherlands Institute of Health Sciences at Erasmus University Rotterdam (NIHES) with a specialisation in epidemiology. Prior to her master’s degree, she completed a Bachelor’s degree in Health Sciences at Simon Fraser University. With a background in public health, her goal is to create accurate scientific content that is easy to understand and empowers people to make informed decisions. Within Homed-IQ, Lauren works as a Product Developer and Content Lead, working closely with physicians and scientists on medical devices for Homed-IQ’s new products and written communications.