Table of ContentsView AllTable of ContentsWhat Is Hyperthyroidism?What Is Hypothyroidism?ComplicationsDiagnosisTreatment
Table of ContentsView All
View All
Table of Contents
What Is Hyperthyroidism?
What Is Hypothyroidism?
Complications
Diagnosis
Treatment
Hyperthyroidismis an overactive thyroid gland that produces too much thyroid hormone, whilehypothyroidismis an underactive thyroid gland that produces too little thyroid hormone. Although both share many of the symptoms, there are certain symptoms distinctive of each.
Both hyperthyroidism and hypothyroidism are largely the result of anautoimmune disease, but there are other potential causes as well. The diagnosis and treatment also differ.
Verywell / Michela Buttignol
Hyperthyroidism occurs when the butterfly-shaped organ in the neck called thethyroid glandproduces excessive amounts of thyroid hormones known astriiodothyronine(T3) andtetraiodothyronine(T4).These hormones, composed largely ofiodine, help regulate many body functions, including growth, heart rate, andmetabolism(the conversion of calories into energy).
Hyperthyroidism may involve the thyroid gland itself or a pea-sized organ in the brain called thepituitary glandwhich directs the secretion of T3 and T4.
Symptoms
The overproduction of T3 and T4 can cause an array of symptoms affecting your hair, weight, digestion, heart rate, energy levels, moods, body temperature, and menstrual cycle.
Common signs and symptoms of hyperthyroidism include:
Causes
Hyperthyroidism can be due to conditions that cause thyroidinflammation(referred to asthyroiditis) or the development of nodules that secrete T3 and T4 irrespective of the pituitary gland.
Common causes of hyperthyroidism include:
Hypothyroidism occurs when the body doesn’t produce enough thyroid hormones. It involves conditions that damage the thyroid gland itself (called primary hypothyroidism), the pituitary gland (called secondary hypothyroidism), or a part of the brain that stimulates the pituitary gland called thehypothalamus(called tertiary hypothyroidism).
The underproduction of T3 and T4 can also cause symptoms affecting your hair, weight, digestion, heart rate, energy levels, moods, body temperature, and menstrual cycle, often in significantly different ways to hyperthyroidism.
Common signs and symptoms of hypothyroidism include:
Primary hypothyroidism is about a thousand times more common than secondary and tertiary hypothyroidism.Some of the same conditions that cause hyperthyroidism can also cause hypothyroidism.
Primary causes of hypothyroidism include:
Secondary and tertiary causes of hypothyroidism include:
When hyperthyroidism and hypothyroidism are left untreated, they can lead to complications, some of which may be serious. These complications involve many of the same organ systems but often in very different ways.
Hyperthyroidism
Complications of untreated hyperthyroidism include:
Babies born to mothers with Graves' disease are also at increased risk of developing hyperthyroidism.
Hypothyroidism
Complications of untreated hypothyroidism include:
For both hyperthyroidism and hypothyroidism, your healthcare provider will take a medical history, do a physical exam, and order one or more blood tests to check your thyroid function.
Based on the results of the TSH and T4 tests:
Thyroid antibody testsmay help diagnose autoimmune hyperthyroidism, either in the form of Graves' disease or Hashimoto’s disease.
The treatments for hyperthyroidism are different from those for hypothyroidism. One aims to stem the production of T3 and T4, while the other aims to replace thyroid hormones with synthetic or natural thyroid hormones.
Medications, radiation, surgery, or a combination of treatments may be prescribed to treat hyperthyroidism. This may include:
Hyperthyroidism ishighly treatable, with between 20% and 30% of people with Graves’ disease entering long-term remission with treatment.
The treatment of hypothyroidism is focused on replacing T4 with a biologically equivalent thyroid hormone calledlevothyroxine(marketed under the brand name Synthroid, Levo-T, and others). Taken daily, it can start to normalize thyroid hormone levels within one to two weeks.
Generally speaking, you won’t need a bioequivalent form of T3, calledCytomel (liothyronine), because T4 is naturally converted in the body into T3. Even so, some providers will add Cytomel to the treatment plan if you have not had success taking T4 on its own or are still struggling with thyroid symptoms.
Though not endorsed as part of standard hypothyroid care, a natural hormone product calledArmour Thyroid (desiccated thyroid)derived from pigs has been used for generations to treat hypothyroidism.
Summary
Hyperthyroidism is an overactive thyroid gland, and hypothyroidism is an underactive thyroid gland. The main cause of each is autoimmune thyroid disease (respectively, Graves' disease and Hashimoto’s disease). Hyperthyroid treatment is based on slowing thyroid hormone production, while hypothyroid treatment involves hormone replacement therapy.
Both can cause fatigue, hair loss, and pregnancy complications, but hyperthyroidism is more likely to cause diarrhea, rapid heartbeats, increased sweating, anxiety, and sensitivity to heat. Hypothyroidism, on the other hand, is more likely to cause constipation, slowed heartbeats, reduced sweating, depression, and sensitivity to heat.
A Word From VerywellThyroid disease is common, and both hypothyroidism and hyperthyroidism have different symptoms and complications. Most people with thyroid disease can manage their condition with medication or medical procedures. If you suspect you have undiagnosed thyroid disease or that your thyroid disease could be better treated, talk to your healthcare provider.—ISABEL CASIMIRO, MD, PHD, MEDICAL EXPERT BOARD
A Word From Verywell
Thyroid disease is common, and both hypothyroidism and hyperthyroidism have different symptoms and complications. Most people with thyroid disease can manage their condition with medication or medical procedures. If you suspect you have undiagnosed thyroid disease or that your thyroid disease could be better treated, talk to your healthcare provider.—ISABEL CASIMIRO, MD, PHD, MEDICAL EXPERT BOARD
Thyroid disease is common, and both hypothyroidism and hyperthyroidism have different symptoms and complications. Most people with thyroid disease can manage their condition with medication or medical procedures. If you suspect you have undiagnosed thyroid disease or that your thyroid disease could be better treated, talk to your healthcare provider.
—ISABEL CASIMIRO, MD, PHD, MEDICAL EXPERT BOARD
15 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.Office on Women’s Health.Thyroid disease.MedlinePlus.gov.Triiodothyronine (T3) tests.American Thyroid Association.Thyroid function tests.American Thyroid Association.Hyperthyroidism (overactive).National Institute of Diabetes and Digestive and Kidney Diseases.Hyperthyroidism (overactive thyroid).Icahn School of Medicine at Mount Sinai.Hypothyroidism.Persani L, Bonomi M.The multiple genetic causes of central hypothyroidism.Best Practice & Research Clinical Endocrinology & Metabolism. 2017;31(2):255-263. doi:10.1016/j.beem.2017.04.003National Institute of Diabetes and Digestive and Kidney Diseases.Hypothyroidism (underactive thyroid).Beck-Peccoz P, Rodari G, Giavoli C, et al.Central hypothyroidism — a neglected thyroid disorder.Nat Rev Endocrinol.2017:13: 588–598. doi:10.1038/nrendo.2017.47MedlinePlus.gov.Thyroid storm.Banigé M, Polak M, Luton D, Research Group for Perinatal Dysthyroidism (RGPD) Study Group.Prediction of neonatal hyperthyroidism.J Pediatr. 2018;197:249-254.e1. doi:10.1016/j.jpeds.2018.01.071National Institute of Diabetes and Digestive and Kidney Diseases.Hypothyroidism.National Institute of Diabetes and Digestive and Kidney Diseases.Thyroid tests.Kim HJ.Long-term management of Graves disease: a narrative review.Journal of Yeungnam Medical Science. 2022;40(1):12. doi:10.12701/jyms.2022.00444McAninch EA, Bianco AC.The history and future of treatment of hypothyroidism.Ann Intern Med. 2016;164(1):50–56. doi:10.7326/M15-1799
15 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.Office on Women’s Health.Thyroid disease.MedlinePlus.gov.Triiodothyronine (T3) tests.American Thyroid Association.Thyroid function tests.American Thyroid Association.Hyperthyroidism (overactive).National Institute of Diabetes and Digestive and Kidney Diseases.Hyperthyroidism (overactive thyroid).Icahn School of Medicine at Mount Sinai.Hypothyroidism.Persani L, Bonomi M.The multiple genetic causes of central hypothyroidism.Best Practice & Research Clinical Endocrinology & Metabolism. 2017;31(2):255-263. doi:10.1016/j.beem.2017.04.003National Institute of Diabetes and Digestive and Kidney Diseases.Hypothyroidism (underactive thyroid).Beck-Peccoz P, Rodari G, Giavoli C, et al.Central hypothyroidism — a neglected thyroid disorder.Nat Rev Endocrinol.2017:13: 588–598. doi:10.1038/nrendo.2017.47MedlinePlus.gov.Thyroid storm.Banigé M, Polak M, Luton D, Research Group for Perinatal Dysthyroidism (RGPD) Study Group.Prediction of neonatal hyperthyroidism.J Pediatr. 2018;197:249-254.e1. doi:10.1016/j.jpeds.2018.01.071National Institute of Diabetes and Digestive and Kidney Diseases.Hypothyroidism.National Institute of Diabetes and Digestive and Kidney Diseases.Thyroid tests.Kim HJ.Long-term management of Graves disease: a narrative review.Journal of Yeungnam Medical Science. 2022;40(1):12. doi:10.12701/jyms.2022.00444McAninch EA, Bianco AC.The history and future of treatment of hypothyroidism.Ann Intern Med. 2016;164(1):50–56. doi:10.7326/M15-1799
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.
Office on Women’s Health.Thyroid disease.MedlinePlus.gov.Triiodothyronine (T3) tests.American Thyroid Association.Thyroid function tests.American Thyroid Association.Hyperthyroidism (overactive).National Institute of Diabetes and Digestive and Kidney Diseases.Hyperthyroidism (overactive thyroid).Icahn School of Medicine at Mount Sinai.Hypothyroidism.Persani L, Bonomi M.The multiple genetic causes of central hypothyroidism.Best Practice & Research Clinical Endocrinology & Metabolism. 2017;31(2):255-263. doi:10.1016/j.beem.2017.04.003National Institute of Diabetes and Digestive and Kidney Diseases.Hypothyroidism (underactive thyroid).Beck-Peccoz P, Rodari G, Giavoli C, et al.Central hypothyroidism — a neglected thyroid disorder.Nat Rev Endocrinol.2017:13: 588–598. doi:10.1038/nrendo.2017.47MedlinePlus.gov.Thyroid storm.Banigé M, Polak M, Luton D, Research Group for Perinatal Dysthyroidism (RGPD) Study Group.Prediction of neonatal hyperthyroidism.J Pediatr. 2018;197:249-254.e1. doi:10.1016/j.jpeds.2018.01.071National Institute of Diabetes and Digestive and Kidney Diseases.Hypothyroidism.National Institute of Diabetes and Digestive and Kidney Diseases.Thyroid tests.Kim HJ.Long-term management of Graves disease: a narrative review.Journal of Yeungnam Medical Science. 2022;40(1):12. doi:10.12701/jyms.2022.00444McAninch EA, Bianco AC.The history and future of treatment of hypothyroidism.Ann Intern Med. 2016;164(1):50–56. doi:10.7326/M15-1799
Office on Women’s Health.Thyroid disease.
MedlinePlus.gov.Triiodothyronine (T3) tests.
American Thyroid Association.Thyroid function tests.
American Thyroid Association.Hyperthyroidism (overactive).
National Institute of Diabetes and Digestive and Kidney Diseases.Hyperthyroidism (overactive thyroid).
Icahn School of Medicine at Mount Sinai.Hypothyroidism.
Persani L, Bonomi M.The multiple genetic causes of central hypothyroidism.Best Practice & Research Clinical Endocrinology & Metabolism. 2017;31(2):255-263. doi:10.1016/j.beem.2017.04.003
National Institute of Diabetes and Digestive and Kidney Diseases.Hypothyroidism (underactive thyroid).
Beck-Peccoz P, Rodari G, Giavoli C, et al.Central hypothyroidism — a neglected thyroid disorder.Nat Rev Endocrinol.2017:13: 588–598. doi:10.1038/nrendo.2017.47
MedlinePlus.gov.Thyroid storm.
Banigé M, Polak M, Luton D, Research Group for Perinatal Dysthyroidism (RGPD) Study Group.Prediction of neonatal hyperthyroidism.J Pediatr. 2018;197:249-254.e1. doi:10.1016/j.jpeds.2018.01.071
National Institute of Diabetes and Digestive and Kidney Diseases.Hypothyroidism.
National Institute of Diabetes and Digestive and Kidney Diseases.Thyroid tests.
Kim HJ.Long-term management of Graves disease: a narrative review.Journal of Yeungnam Medical Science. 2022;40(1):12. doi:10.12701/jyms.2022.00444
McAninch EA, Bianco AC.The history and future of treatment of hypothyroidism.Ann Intern Med. 2016;164(1):50–56. doi:10.7326/M15-1799
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