Table of ContentsView AllTable of ContentsWhat Is Low TSH?Frequent SymptomsCausesComplicationsWhen to See a ProviderTreatment
Table of ContentsView All
View All
Table of Contents
What Is Low TSH?
Frequent Symptoms
Causes
Complications
When to See a Provider
Treatment
Low thyroid stimulating hormone (TSH) levels often occur with hyperthyroidism (overactive thyroid). However, a low TSH test result needs to be evaluated in the context of other thyroid tests and your individual symptoms and health history.
Several conditions can include low TSH levels and hyperthyroidism, includingGraves' diseaseandthyroid nodules. About 1% of adults in the United States have hyperthyroidism.
This article explains TSH levels, why a low TSH might occur, and any low TSH symptoms (though not everyone has them). It also discusses possible causes of low TSH and how it’s treated.
Yoshiyoshi Hirokawa / Getty Images
A combination of TSH level and other thyroid hormone results are needed for diagnosis. For example, circulating T3 increases before T4 in people with hyperthyroidism.The values of these other tests, along with TSH level, are key to understanding and treating the cause.
Normal TSH LevelsNormal TSH levels fall between 0.4 and 4.5 milliunits per liter (mU/L).Within this range, results can vary based on age (TSH tends to be higher in older people), assigned sex (TSH tends to be lower in females), or even time of day. Many people diagnosed with a thyroid disorder can have normal test results.
Normal TSH Levels
Normal TSH levels fall between 0.4 and 4.5 milliunits per liter (mU/L).Within this range, results can vary based on age (TSH tends to be higher in older people), assigned sex (TSH tends to be lower in females), or even time of day. Many people diagnosed with a thyroid disorder can have normal test results.
TSH Levels Test: What Do High and Low Levels Mean?
Symptoms of Low TSH
Though TSH levels are important measures of thyroid function, low TSH levels do not always cause symptoms.However, low TSH symptoms often are associated with hyperthyroidism, which can cause:
Although less common, some rare symptoms of low TSH levels linked to hyperthyroidism include:
Other medical problems, likeanemia(a decrease in red blood cells), can also indicate that someone has low TSH and hyperthyroidism.
Factors That Can Affect Thyroid Test Results
Causes of Low TSH
A low TSH level of less than 0.4 mU/L can be due to several causes, including:
Pregnancy is a common cause of lower TSH levels and associated hyperthyroidism.
Pregnancy Concerns
Mild hyperthyroidism while pregnant does not always cause problems. Moderate-to-severe hyperthyroidism can lead to various complications.
Though uncommon, hyperthyroidism may also occur in mothers of newborns with a history of treated Graves' disease (meaning their disease is in remission). Thus, it’s important to notify your healthcare provider of any history of thyroid disease in addition to active thyroid disease.
How to Tell the Difference Between Hyperthyroidism and Hypothyroidism
Complications of Low TSH
Low TSH levels are an indicator of abnormal thyroid function and should be corrected.
The thyroid plays a central role in numerous body processes, such as energy, metabolism, skin health, mood, and heart function.Over the long term, low TSH levels can potentially lead to damage to major organ systems, so they should not be dismissed.
Serious complications can include:
When to See a Healthcare Provider
A low TSH level is not often a medical emergency. If you have blood work that illustrates a low TSH level, talk with your healthcare provider about the potential causes and the next steps for diagnosis and treatment.
Fortunately, there are numerous treatments available for low TSH levels, including medications and procedures. If you experience any severe symptoms, such as high fever, palpitations, or changes in thinking or memory, seek care immediately.
Treatment for Low TSH
The treatment for low TSH levels will depend on the underlying cause. In many cases, low TSH results are associated with hyperthyroidism that can be treated with:
Summary
The diagnosis and treatment will depend on your TSH level along with the results of other thyroid function tests, as well as other tests your healthcare provider finds necessary when considering your medical history and evaluating any symptoms.
13 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.University of Michigan Health.Hyperthyroidism and Graves' disease.Van Uytfanghe K, Ehrenkranz J, Halsall D, Hoff K, Loh TP, Spencer CA,et al.Thyroid Stimulating Hormone and Thyroid Hormones (Triiodothyronine and Thyroxine): An American Thyroid Association-Commissioned Review of Current Clinical and Laboratory Status.Thyroid. 2023 Sep;33(9):1013-1028. doi:10.1089/thy.2023.0169.American Thyroid Association.Thyroid Function Tests.Lacámara N, Lecumberri B, Barquiel B, Escribano A, González-Casado I, Álvarez-Escolá C, et al.Identification of Resistance to Exogenous Thyroxine in Humans.Thyroid. 2020 Dec;30(12):1732-1744. doi:10.1089/thy.2019.0825.Azim S, Nasr C.Subclinical hypothyroidism: When to treat.Cleve Clin J Med. 2019 Feb;86(2):101-110. doi: 10.3949/ccjm.86a.17053.Stott DJ, Rodondi N, Kearney PM, Ford I, Westendorp RGJ, Mooijaart SP,et al.Thyroid Hormone Therapy for Older Adults with Subclinical Hypothyroidism.N Engl J Med. 2017 Jun 29;376(26):2534-2544. doi:10.1056/NEJMoa1603825.MedlinePlus.Hyperthyroidism.Rajendran A, Bhavani N, Nair V, et al.Oral levothyroxine is an effective option for myxedema coma: a single-centre experience.Eur Thyroid J. Published online June 11, 2020:1-7. doi:10.11592F000507855Wilson SA, Stem LA, Bruehlman RD.Hypothyroidism: diagnosis and treatment.Am Fam Physician. 2021;103(10):605-613.Soh SB, Aw TC.Laboratory Testing in Thyroid Conditions - Pitfalls and Clinical Utility.Ann Lab Med. 2019 Jan;39(1):3-14. doi: 10.3343/alm.2019.39.1.3.Derwahl M, Nicula D.Estrogen and its role in thyroid cancer.Endocr Relat Cancer. 2014;21(5):T273-T283. doi:10.1530/ERC-14-0053American Thyroid Association.Hyperthyroidism in pregnancy.National Institute of Diabetes and Digestive and Kidney Diseases.Hyperthyroidism (overactive thyroid).
13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.University of Michigan Health.Hyperthyroidism and Graves' disease.Van Uytfanghe K, Ehrenkranz J, Halsall D, Hoff K, Loh TP, Spencer CA,et al.Thyroid Stimulating Hormone and Thyroid Hormones (Triiodothyronine and Thyroxine): An American Thyroid Association-Commissioned Review of Current Clinical and Laboratory Status.Thyroid. 2023 Sep;33(9):1013-1028. doi:10.1089/thy.2023.0169.American Thyroid Association.Thyroid Function Tests.Lacámara N, Lecumberri B, Barquiel B, Escribano A, González-Casado I, Álvarez-Escolá C, et al.Identification of Resistance to Exogenous Thyroxine in Humans.Thyroid. 2020 Dec;30(12):1732-1744. doi:10.1089/thy.2019.0825.Azim S, Nasr C.Subclinical hypothyroidism: When to treat.Cleve Clin J Med. 2019 Feb;86(2):101-110. doi: 10.3949/ccjm.86a.17053.Stott DJ, Rodondi N, Kearney PM, Ford I, Westendorp RGJ, Mooijaart SP,et al.Thyroid Hormone Therapy for Older Adults with Subclinical Hypothyroidism.N Engl J Med. 2017 Jun 29;376(26):2534-2544. doi:10.1056/NEJMoa1603825.MedlinePlus.Hyperthyroidism.Rajendran A, Bhavani N, Nair V, et al.Oral levothyroxine is an effective option for myxedema coma: a single-centre experience.Eur Thyroid J. Published online June 11, 2020:1-7. doi:10.11592F000507855Wilson SA, Stem LA, Bruehlman RD.Hypothyroidism: diagnosis and treatment.Am Fam Physician. 2021;103(10):605-613.Soh SB, Aw TC.Laboratory Testing in Thyroid Conditions - Pitfalls and Clinical Utility.Ann Lab Med. 2019 Jan;39(1):3-14. doi: 10.3343/alm.2019.39.1.3.Derwahl M, Nicula D.Estrogen and its role in thyroid cancer.Endocr Relat Cancer. 2014;21(5):T273-T283. doi:10.1530/ERC-14-0053American Thyroid Association.Hyperthyroidism in pregnancy.National Institute of Diabetes and Digestive and Kidney Diseases.Hyperthyroidism (overactive thyroid).
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
University of Michigan Health.Hyperthyroidism and Graves' disease.Van Uytfanghe K, Ehrenkranz J, Halsall D, Hoff K, Loh TP, Spencer CA,et al.Thyroid Stimulating Hormone and Thyroid Hormones (Triiodothyronine and Thyroxine): An American Thyroid Association-Commissioned Review of Current Clinical and Laboratory Status.Thyroid. 2023 Sep;33(9):1013-1028. doi:10.1089/thy.2023.0169.American Thyroid Association.Thyroid Function Tests.Lacámara N, Lecumberri B, Barquiel B, Escribano A, González-Casado I, Álvarez-Escolá C, et al.Identification of Resistance to Exogenous Thyroxine in Humans.Thyroid. 2020 Dec;30(12):1732-1744. doi:10.1089/thy.2019.0825.Azim S, Nasr C.Subclinical hypothyroidism: When to treat.Cleve Clin J Med. 2019 Feb;86(2):101-110. doi: 10.3949/ccjm.86a.17053.Stott DJ, Rodondi N, Kearney PM, Ford I, Westendorp RGJ, Mooijaart SP,et al.Thyroid Hormone Therapy for Older Adults with Subclinical Hypothyroidism.N Engl J Med. 2017 Jun 29;376(26):2534-2544. doi:10.1056/NEJMoa1603825.MedlinePlus.Hyperthyroidism.Rajendran A, Bhavani N, Nair V, et al.Oral levothyroxine is an effective option for myxedema coma: a single-centre experience.Eur Thyroid J. Published online June 11, 2020:1-7. doi:10.11592F000507855Wilson SA, Stem LA, Bruehlman RD.Hypothyroidism: diagnosis and treatment.Am Fam Physician. 2021;103(10):605-613.Soh SB, Aw TC.Laboratory Testing in Thyroid Conditions - Pitfalls and Clinical Utility.Ann Lab Med. 2019 Jan;39(1):3-14. doi: 10.3343/alm.2019.39.1.3.Derwahl M, Nicula D.Estrogen and its role in thyroid cancer.Endocr Relat Cancer. 2014;21(5):T273-T283. doi:10.1530/ERC-14-0053American Thyroid Association.Hyperthyroidism in pregnancy.National Institute of Diabetes and Digestive and Kidney Diseases.Hyperthyroidism (overactive thyroid).
University of Michigan Health.Hyperthyroidism and Graves' disease.
Van Uytfanghe K, Ehrenkranz J, Halsall D, Hoff K, Loh TP, Spencer CA,et al.Thyroid Stimulating Hormone and Thyroid Hormones (Triiodothyronine and Thyroxine): An American Thyroid Association-Commissioned Review of Current Clinical and Laboratory Status.Thyroid. 2023 Sep;33(9):1013-1028. doi:10.1089/thy.2023.0169.
American Thyroid Association.Thyroid Function Tests.
Lacámara N, Lecumberri B, Barquiel B, Escribano A, González-Casado I, Álvarez-Escolá C, et al.Identification of Resistance to Exogenous Thyroxine in Humans.Thyroid. 2020 Dec;30(12):1732-1744. doi:10.1089/thy.2019.0825.
Azim S, Nasr C.Subclinical hypothyroidism: When to treat.Cleve Clin J Med. 2019 Feb;86(2):101-110. doi: 10.3949/ccjm.86a.17053.
Stott DJ, Rodondi N, Kearney PM, Ford I, Westendorp RGJ, Mooijaart SP,et al.Thyroid Hormone Therapy for Older Adults with Subclinical Hypothyroidism.N Engl J Med. 2017 Jun 29;376(26):2534-2544. doi:10.1056/NEJMoa1603825.
MedlinePlus.Hyperthyroidism.
Rajendran A, Bhavani N, Nair V, et al.Oral levothyroxine is an effective option for myxedema coma: a single-centre experience.Eur Thyroid J. Published online June 11, 2020:1-7. doi:10.11592F000507855
Wilson SA, Stem LA, Bruehlman RD.Hypothyroidism: diagnosis and treatment.Am Fam Physician. 2021;103(10):605-613.
Soh SB, Aw TC.Laboratory Testing in Thyroid Conditions - Pitfalls and Clinical Utility.Ann Lab Med. 2019 Jan;39(1):3-14. doi: 10.3343/alm.2019.39.1.3.
Derwahl M, Nicula D.Estrogen and its role in thyroid cancer.Endocr Relat Cancer. 2014;21(5):T273-T283. doi:10.1530/ERC-14-0053
American Thyroid Association.Hyperthyroidism in pregnancy.
National Institute of Diabetes and Digestive and Kidney Diseases.Hyperthyroidism (overactive thyroid).
Meet Our Medical Expert Board
Share Feedback
Was this page helpful?Thanks for your feedback!What is your feedback?OtherHelpfulReport an ErrorSubmit
Was this page helpful?
Thanks for your feedback!
What is your feedback?OtherHelpfulReport an ErrorSubmit
What is your feedback?
