What Does It Mean When Your TSH Level Is Low?

Reviewed on 3/5/2021

Low TSH level

Low thyroid-stimulating hormone (TSH) levels
Too much thyroid hormone production (endogenous hyperthyroidism): The most common cause of overactive thyroid is a condition called Graves’ disease.

Having low thyroid-stimulating hormone (TSH) levels means that your thyroid gland is producing thyroid hormones in excess, a case called hyperthyroidism. In this condition, a small gland located at the base of your brain (the pituitary gland) decreases the amount of TSH it secretes to offset the high amount of thyroid hormones (namely, thyroxine and triiodothyronine) in your body. 

Main causes of low TSH: 

  • Too much thyroid hormone production (endogenous hyperthyroidism): The most common cause of overactive thyroid is a condition called Graves’ disease that is hereditary (passed down in families). Graves’ disease is an autoimmune disease in which the body's immune system affects the thyroid gland causing it to produce too much thyroid hormone.
  • There is too much or overdosage of thyroid medication (exogenous hyperthyroidism).
  • There is not enough production of TSH from the pituitary gland.
  • Benign (non-cancer) tumors of the thyroid (called thyroid nodules) or pituitary gland also cause low TSH.
  • There is too much iodine in the body, which can be caused by taking iodine supplements such as kelp or seaweed.
  • Inflammation of the thyroid gland is possibly caused by a virus or problem with the immune system.
  • Some medicines such as lithium or amiodarone can cause an overactive thyroid.

The symptoms of low TSH levels may include:


  • Fatigue, nervousness, restlessness, and weakness are common symptoms of low TSH. 
  • Muscle cramps may also occur due to low TSH.
  • People with low TSH may be very sensitive to the heat and unable to tolerate it.
  • A warm summer day for most people may be unbearably hot for those with low TSH. They may also sweat more than others.


  • The skin may be unusually warm and may even have a reddish hue from the increased blood flow that can occur with a low TSH (and consequent high thyroid hormones). 
  • The skin may become darker or smoother than usual. 
  • Hair thinning may be noted. Hives and itching may also occur. 
  • The skin of the shins may be affected, appearing raised or darker than usual, and it may resemble the peel of a shrunken orange.

Heart and lungs

Digestive system: 

  • Most people with low TSH have an increased appetite. 
  • But they can still lose weight, despite eating more than usual because their metabolism is revved up. 
  • However, senior citizens with low TSH may have a decreased appetite rather than an increased appetite. 
  • Some people with low TSH have an enlarged thyroid gland, called a goiter. If the goiter is big enough, it can cause difficulty swallowing
  • Having more frequent bowel movements is common in TSH.

Personality and thinking: 

  • Some people with a low TSH experience depression due to hormone fluctuations.
  • Confusion, difficulty concentrating, and memory problems may occur. 
  • Other potential symptoms include insomnia (lack of sleep), anxiety, and irritability.

Treatment: The choice of treatment will be influenced by the patient’s age, the type of overactive thyroid that they have, the severity of the condition, and other medical conditions that may be affecting the patient’s health. The possible treatments for overactive thyroid are:


  • Beta-blockers such as propranolol or metoprolol: These medicines relieve symptoms such as shaking or tremors and fast heartbeat. These medicines are given for a short time and can help feel better while the doctor decides what the treatment should be.
  • Antithyroid medications such as carbimazole: This helps to reduce the amount of thyroid hormone that is produced by the glands. 

Radioactive iodine therapy:

  • This involves taking a drink or swallowing a capsule, which contains radioactive iodine.
  • This damages the cells that produce the thyroid hormones in the thyroid gland.


  • This involves a procedure in which all or part of the thyroid gland is removed.
  • This is often the last resort and is a consideration if all other therapies and medication have not worked. People often consider surgery if they are at a higher risk of experiencing side effects from other treatments.
  • Surgery is a good option if one has a large swelling (called a goiter) that causes problems in the neck.

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Hyperthyroidism (Overactive Thyroid): https://www.webmd.com/a-to-z-guides/overactive-thyroid-hyperthyroidism#1

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