What is thyroid-stimulating hormone (TSH)?

Medically reviewed by Neka Miller, PhD on February 11, 2021. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Interested in learning more about your thyroid health and wondering, “What is thyroid-stimulating hormone (TSH)?” Here, we break down what TSH is and how your levels can impact your health, so read on to learn more.

Check if your thyroid hormones are balanced from the convenience of home with the Everlywell at-home Thyroid Test.


What is thyroid-stimulating hormone?

Thyroid-stimulating hormone (TSH) is a hormone produced and released into the bloodstream by the pituitary gland, which regulates the production of hormones by the thyroid gland.

It controls production of thyroxine (T4) and triiodothyronine (T3), two important thyroid hormones essential to maintaining the body’s metabolic rate, heart and digestive functions, muscle control, brain development, and maintenance of bones.

What happens when your TSH level is high?

A TSH test can help you identify if your thyroid-stimulating hormone levels are too high.

If you have too much TSH, this may indicate that your thyroid gland is not producing enough thyroid hormone (in other words, it’s underactive). An underactive thyroid is also known as hypothyroidism.

Common symptoms of hypothyroidism may include:

  • Weight gain, even without changes in your diet or activity level
  • Fatigue
  • Chronic hoarse voice
  • Dry skin
  • Constipation
  • Puffy face
  • Joint pain
  • Muscle aches or weakness
  • Thinning hair or hair loss
  • Heavy or irregular periods
  • Infertility
  • Goiter (enlarged thyroid gland, which usually appears as a lump at the base of your throat)

To treat hypothyroidism, your healthcare provider may suggest you take medication to bring the level of thyroid hormones back to normal. It’s important to note that it’s particularly important for pregnant women to have the correct amounts of thyroid-stimulating hormone and thyroid hormones to ensure the healthy development of their babies.

What happens when TSH is too low?

Having too little TSH may be an indication that your body is overproducing thyroid hormones, also known as hyperthyroidism.

Common symptoms of hyperthyroidism may include:

  • Unintentional weight loss, even without dietary changes
  • Rapid heartbeat (known as tachycardia)
  • Irregular heartbeat (arrhythmia) and a pounding heart (called palpitations)
  • Increased appetite
  • Mood changes, including nervousness, anxiety, and irritability
  • Hand and finger tremors
  • Sweating
  • Changes in your menstrual cycle
  • New or worsened heat sensitivity
  • More frequent bowel movements
  • An enlarged thyroid gland (goiter)
  • Fatigue
  • Weak muscles
  • Problems with your sleep
  • Thinner skin, which is more susceptible to cuts and bruises
  • Fine hair which easily breaks

One possible treatment for hyperthyroidism is medication that helps reduce the activity of the thyroid gland with the goal of returning all thyroid hormone levels to normal. Rarely, problems in the pituitary gland can also result in a low thyroid-stimulating hormone level.

Interested in checking your thyroid hormone levels? Take action now with the Everlywell at-home Thyroid Test and check if your thyroid hormones (including TSH) are balanced from the comfort of your home. You collect your own sample, mail it to a lab for testing, and get your digital, physician-reviewed results in days.

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1. Thyroid Disease. Cleveland Clinic. URL. Accessed February 11, 2021.

2. Thyroid stimulating hormone. You and Your Hormones. URL. Accessed February 11, 2021.

3. Hypothyroidism (underactive thyroid). Mayo Clinic. URL. Accessed February 11, 2021.

4. Thyroid Disease & Pregnancy. National Institute of Diabetes and Digestive and Kidney Diseases. URL. Accessed February 11, 2021.

5. Hyperthyroidism (overactive thyroid). Mayo Clinic. URL. Accessed February 11, 2021.

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