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What is TSH and how to interpret your TSH level

Updated: Mar 27, 2023

When talking about the thyroid gland and possible health problems related to it, it is important to know more about the hormone called TSH (thyroid-stimulating hormone).

How does the thyroid work?

The thyroid gland is located in the front of the neck and plays a key role in many of the basic functions of the human body such as its metabolism and energy regulation. The work of this gland is controlled by the pituitary gland and the hypothalamus.

It is the pituitary gland (a small endocrine organ located at the base of the brain) that produces TSH, which in turn stimulates the production and release of thyroid hormones. In other words, the pituitary gland and its hormone (TSH) communicate to the thyroid gland how many hormones it should release.

How do thyroid hormones and TSH interact?

As a result of the TSH stimulus, the thyroid gland produces two main hormones – triiodothyronine (T3) and thyroxine (T4). These thyroid hormones regulate our metabolism, oxygen consumption, energy balance, heat production, and other vital body functions.

When thyroid hormone levels are too low, the TSH level rises (a condition called hypothyroidism). Conversely, when thyroid hormones are too high, the TSH level is usually below the norm (hyperthyroidism).

Therefore, measuring the TSH level in the blood can be a reliable indication of any cause for concern in the thyroid’s function. The THYRO-Check® test can easily and quickly provide you with the results you need even at home.

Good to know: There is a third hormone produced by the thyroid gland called calcitonin. It has nothing to do with hormonal changes, but it is responsible for regulating calcium and phosphorus in the body.

How do you interpret the level of TSH in the blood?

When taking a blood sample from a healthy person, the TSH level should not fall below 0.45 µIU/mL and should not exceed the upper limit of 4.5 µIU/mL. For pregnant women, these reference values would be different because the physiology of the thyroid gland changes during pregnancy.

The level of TSH in the blood can also vary depending on the age and sex of the person.

When the level of TSH is above the norm, you may be diagnosed with hypothyroidism (inactive thyroid gland). In most cases, hypothyroidism develops as a result of an autoimmune disease known as Hashimoto’s disease. Your metabolism slows down and you may experience symptoms such as fatigue, weight gain, poor sleep, and depression.

In the opposite case, when the TSH is below the lower reference limit, you may have a condition called hyperthyroidism – an overactive thyroid gland. The most common cause of hyperthyroidism is an autoimmune disease known as Graves’ disease. Symptoms include irritability, intolerance to heat, sweating, and sleep disturbances.

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