TSH
TSH stands for “thyroid stimulating hormone” and the test measures how much of this hormone is in your blood. TSH is produced by the pituitary gland in your brain. This gland tells your thyroid to make and release the thyroid hormones into your blood.
The thyroid is small, butterfly-shaped gland located in the front of the neck. It’s an important gland that creates three primary hormones: triiodothyronine (T3)، thyroxine (T4)and calcitonin.The thyroid controls numerous different bodily functions, including metabolism and growth, through the release of these three hormones. In general, the TSH test is performed to determine the following:
- A TSH test is often performed to determine the underlying cause of abnormal thyroid hormone levels.
- It’s also used to screen for an underactive or overactive thyroid gland.
- By measuring the level of TSH in the blood, your doctor can determine how well the thyroid is working.
Normal TSH level
The normal range of TSH levels is 0.4 to 4.0 milli-international units per liter. If you’re already being treated for a thyroid disorder, the normal range is 0.5 to 3.0 milli-international units per liter.
- A value above the normal range usually indicates that the thyroid is underactive. This indicates hypothyroidism. When the thyroid isn’t producing enough hormones, the pituitary gland releases more TSH to try to stimulate it.
- A value below the normal range means that the thyroid is overactive. This indicates hyperthyroidism. When the thyroid is producing too many hormones, the pituitary gland releases less TSH.
Depending on the results, your doctor may want to perform additional tests to confirm the diagnosis.
Why Is a Thyroid-Stimulating Hormone Test Performed?
Your doctor may order a TSH test if you’re experiencing symptoms of a thyroid disorder. Thyroid diseases can be categorized as either hypothyroidism or hyperthyroidism.
Hypothyroidism
Hypothyroidism is a condition in which the thyroid produces too few hormones, causing metabolism to slow down. The symptoms of hypothyroidism include fatigue, weakness, and difficulty concentrating. The following are some of the most common causes of hypothyroidism:
- Hashimoto’s disease
- Thyroiditis (thyroid inflammation)
- Postpartum thyroiditis
- Iodine deficiency in the body
Hyperthyroidism
Hyperthyroidism is a condition in which the thyroid produces too many hormones, causing the metabolism to speed up. Symptoms of hyperthyroidism include increased appetite, anxiety, and difficulty sleeping. The following are some of the most common causes of hyperthyroidism:
- Graves’ disease
- Thyroiditis (in a short time, hyperthyroidism and then hypothyroidism (
- Increased iodine overdose
- Thyroid nodules
Normal TSH levels in different individuals and conditions
The normal range of TSH depends on a person’s gender, age, and medical condition, which can vary greatly.
Gender: Females are more likely to experience thyroid dysfunction than males. The risk of thyroid problems increases during pregnancy and around menopause.
Age: Blood TSH levels tend to increase as a person gets older.
Pregnancy: TSH levels tend to be lower in pregnant women.Pregnancy hormones naturally increase the levels of certain thyroid hormones in the blood. This is essential for the development of the fetal brain and nervous system. At the same time, the levels of TSH in the blood decrease. As a result, doctors use lower reference ranges for pregnant women. The lower TSH range is decreased by around 0.1 to 0.2 mU/l and the upper limit is decreased by around 0.5 to 1.0 mU/l. Doctors carefully monitor TSH levels throughout pregnancy. Having unusually high or low levels can affect the risk of miscarriage and cause pregnancy-related complications, such as:
- preeclampsia
- premature birth
- low birth weight
- congestive heart failure
Children: TSH levels are highest at birth and gradually decrease as a child gets older.
Reference
https://www.healthline.com/health/tsh#results
