Thyroid Disease: Types, Symptoms, Tests and Treatment
Updated: 11 minutes ago
Medically reviewed by Dr. Baraa Alnahhal, MD · Last reviewed: October 2026
Quick Answer: What is thyroid disease?
Thyroid disease is a general term for a condition that affects how much thyroid hormone the thyroid makes. The two main patterns are too little hormone, called hypothyroidism, and too much hormone, called hyperthyroidism. Because thyroid hormones influence metabolism, changes can affect energy, weight, temperature sensitivity, heart rate, mood and menstrual cycles. [1]
Question | Short answer |
What is the thyroid? | A small, butterfly-shaped gland at the front of the neck that makes thyroid hormones (T4 and T3). |
What are the main types? | Hypothyroidism (underactive) and hyperthyroidism (overactive). |
How common is it? | About 20 million people in the United States have some type of thyroid condition. |
How is it diagnosed? | Symptom review, physical exam, blood tests and sometimes imaging. |
Is it treatable? | Usually yes, often with medication. |
What the research says
Thyroid problems are common in pregnancy. A systematic review and meta-analysis of 48 studies found that 16.12% of pregnant women had thyroid dysfunction (95% CI 13.97%–18.27%). Subclinical hypothyroidism was the most common type (11.53%), followed by overt hypothyroidism (3.29%), subclinical hyperthyroidism (1.56%) and overt hyperthyroidism (1.13%). Results varied widely between studies (Zenaw et al., Womens Health, 2026). [2]
Thyroid dysfunction is linked to type 2 diabetes. A meta-analysis of 36 studies found pooled risk estimates for type 2 diabetes of 3.63 (95% CI 1.63–8.09) with hypothyroidism and 16.33 (95% CI 7.59–35.12) with overt hypothyroidism. People with thyroid dysfunction also had higher HbA1c and fasting glucose levels. These are associations from observational studies (Amirabadizadeh et al., J Diabetes Metab Disord, 2025). [3]
Autoimmune disease and thyroid disease often travel together. A systematic review and meta-analysis found that people with systemic lupus erythematosus had a higher prevalence of clinical hypothyroidism, subclinical hyperthyroidism and euthyroid sick syndrome than healthy controls, and that kidney involvement and low free T3 were associated with clinical hypothyroidism (Li et al., Front Immunol, 2026). [4]
What does the thyroid do?
The thyroid is a small gland shaped like a butterfly. It sits at the front of the neck under the skin and is part of the endocrine system. It produces and releases thyroid hormones, including thyroxine (T4) and triiodothyronine (T3). Learn more in our guides to the thyroid gland and the endocrine system. [1]
The thyroid’s main job is to control the speed of metabolism, which is how the body transforms food into energy. Every cell needs energy to function, so thyroid problems can affect many parts of the body. [1]
What are the main types of thyroid disease?
The two main types are hypothyroidism and hyperthyroidism. See our full guides to hypothyroidism and hyperthyroidism.
Type | Meaning | Common symptom pattern |
Hypothyroidism | The thyroid is underactive and does not make enough thyroid hormone | Slower body processes, fatigue, weight gain and cold sensitivity |
Hyperthyroidism | The thyroid is overactive and makes too much thyroid hormone | Faster body processes, weight loss, sweating and a faster heart rate |
Symptoms can overlap with other medical conditions or life stages. Testing is needed to determine whether symptoms are related to a thyroid problem.
What causes hypothyroidism?
Cause | How it relates to hypothyroidism |
Hashimoto’s disease | A chronic autoimmune condition that can cause an underactive thyroid; it is the most common cause in countries with widely available iodized salt and iodine-enriched foods |
Iodine deficiency | The thyroid needs iodine to make thyroid hormone; deficiency can lead to hypothyroidism and often goiter, or an enlarged thyroid |
Congenital hypothyroidism | A baby is born with a missing or underactive thyroid; about 1 in 2,000 to 4,000 babies are affected |
For newborns, see our guide to congenital hypothyroidism.
What causes hyperthyroidism?
Hyperthyroidism can be caused by Graves' disease, thyroid nodules and thyroiditis, including postpartum thyroiditis, which can cause temporary hyperthyroidism after pregnancy. [1]
Cause | How it relates to hyperthyroidism |
Graves’ disease | A chronic autoimmune condition and the most common cause of hyperthyroidism |
Thyroid nodules | Abnormal lumps that can produce excess hormone when they are hyperfunctioning |
Excessive iodine | Too much iodine can cause the thyroid to make more hormone than the body needs; certain medications, such as amiodarone, can contribute |
Read more about Graves’ disease and thyroid nodules.
Thyroiditis, which is inflammation of the thyroid, can cause temporary hyperthyroidism followed by temporary or chronic hypothyroidism. Postpartum thyroiditis can affect some birthing parents after pregnancy and typically causes hyperthyroidism followed by hypothyroidism. An estimated 5% of people may experience it in the year after giving birth, and it is usually temporary. [1]
How common is thyroid disease?
Thyroid disease is very common. About 20 million people in the United States have some type of thyroid condition, and it can affect people of all ages. [1]
What are the symptoms of hypothyroidism?
Hypothyroidism is an underactive thyroid, and because it slows metabolism, it can cause a range of symptoms. Because metabolism slows, symptoms may include:
Symptom | What it may look like |
Slower heart rate | A pulse that is slower than usual |
Fatigue | Feeling unusually tired |
Weight gain | Weight gain without an obvious explanation |
Cold sensitivity | Feeling colder than usual |
Skin and hair changes | Dry skin or dry, coarse hair |
Depressed mood | Low or depressed mood |
Heavy menstrual periods | Menstrual bleeding that is heavier than usual |
What are the symptoms of hyperthyroidism?
Hyperthyroidism is an overactive thyroid, and because it speeds up metabolism, it can cause a range of symptoms. Because metabolism speeds up, symptoms may include:
Symptom | What it may look like |
Faster heart rate | A pulse that is faster than usual, also called tachycardia |
Sleep difficulty | Trouble falling asleep or staying asleep |
Weight loss | Weight loss without an obvious explanation |
Heat sensitivity | Feeling hotter than usual |
Sweating | Clammy or sweaty skin |
Mood and nervous-system changes | Feeling anxious, irritable or nervous |
Menstrual changes | Irregular cycles or a lack of periods, called amenorrhea |
Both conditions can cause an enlarged thyroid, called a goiter, although goiter is more common in hyperthyroidism. [1]
Who is at higher risk of thyroid disease?
Thyroid disease risk factors do not establish a diagnosis, since a provider considers symptoms, history, examination and test results together.
Risk factor | Details |
Female sex | Females are five to eight times more likely to have a thyroid condition |
Family history | Thyroid disease often runs in families |
Turner syndrome | This genetic condition is a listed risk factor |
Iodine-related medicines | Some medications contain high amounts of iodine |
Iodine-poor setting | Living in an area without widely available iodized table salt can contribute to iodine deficiency |
Older age | Risk is higher after age 60, especially for females |
Radiation therapy | Prior radiation to the head or neck is a listed risk factor |
Autoimmune disease | Pernicious anemia, type 1 diabetes, celiac disease, Addison’s disease, lupus, rheumatoid arthritis and Sjögren’s syndrome |
Related reading: Turner syndrome, celiac disease, Addison’s disease, lupus, rheumatoid arthritis and Sjögren’s syndrome.
A risk factor does not establish a diagnosis. A provider considers symptoms, history, examination and test results together.
How is thyroid disease diagnosed?
A healthcare provider usually begins by asking about symptoms and medical history and performing a physical exam. They may gently feel the thyroid to check whether it is enlarged or whether there are noticeable nodules. [1]
Test | What it can help assess |
TSH blood test | Thyroid-stimulating hormone levels (TSH comes from the pituitary gland) |
T3 and T4 blood tests | Levels of the main thyroid hormones |
Thyroid antibody tests | Evidence related to autoimmune thyroid conditions |
Thyroid ultrasound | Nodules or goiter |
Thyroid uptake and scan | Whether nodules are overactive |
A single symptom or test result should not be interpreted in isolation. Ask the ordering provider what each result means in the context of your symptoms and medical history. See also our guide to the pituitary gland.
How is thyroid disease treated?
Treatment depends on the type of thyroid condition and its cause. The goal is to return thyroid hormone levels to a healthy range. [1]
Treatment for hyperthyroidism
Treatment | Role |
Antithyroid drugs | Methimazole and propylthiouracil stop the thyroid from making hormones |
Radioiodine therapy | Damages thyroid cells to prevent high hormone production (see our guide to radioactive iodine therapy) |
Beta-blockers | Help manage symptoms such as rapid heart rate but do not change thyroid function |
Thyroidectomy | Surgically removes the thyroid for a more permanent form of treatment; lifelong synthetic thyroid replacement is needed afterward |
Learn more about radioactive iodine therapy.
Treatment for hypothyroidism
The main treatment is thyroid replacement medication, which adds manufactured thyroid hormone back into the body. Levothyroxine is one medication providers commonly prescribe. [1]
Medication choice, monitoring and dose changes require clinical guidance. Do not start, stop or change thyroid medicine based on an article alone.
Can thyroid disease cause complications?
Thyroid disease is usually not serious when consistently managed, but untreated or undertreated disease can cause complications.
Condition | Possible complications |
Untreated or undertreated hyperthyroidism | Atrial fibrillation, stroke, congestive heart failure and osteoporosis |
Untreated or undertreated hypothyroidism | Mood disorders such as depression, peripheral neuropathy, increased risk of heart disease and heart failure, infertility and myxedema coma |
Myxedema coma is a sudden, life-threatening complication of severe hypothyroidism. Urgent medical care is needed for severe or rapidly worsening symptoms. [1]
Can you prevent thyroid disease?
Most thyroid diseases are not preventable because many cases are linked to genetics or autoimmune conditions. Thyroid problems related to iodine excess or deficiency may be preventable in some circumstances. If you are concerned about whether you are consuming a healthy amount of iodine, discuss it with a healthcare provider rather than changing supplements or diet on your own. [1]
How can people live well with thyroid disease?
Thyroid disease is often lifelong and may require daily medication, regular monitoring and treatment adjustments. It can take time to find the right plan for hormone levels. With consistent management, people can usually live a normal life with thyroid disease. [1]
If a biological family member has thyroid disease, tell your healthcare provider so the information can be included in your medical record. Family history may be useful if symptoms develop later.
When should you see a healthcare provider?
See a healthcare provider if you have symptoms of hypothyroidism or hyperthyroidism, or if you notice a change in the appearance of your neck where the thyroid is located. Getting a diagnosis can help you begin appropriate treatment. [1]
Seek urgent care for severe or rapidly worsening symptoms, especially symptoms that could reflect a serious heart, neurologic or metabolic complication.
Conclusion: thyroid disease is treatable and manageable
Thyroid disease describes conditions that affect thyroid hormone production. Hypothyroidism is linked with too little thyroid hormone and may slow body processes. Hyperthyroidism involves too much thyroid hormone and may speed them up. [1]
Symptoms can include changes in energy, weight, temperature sensitivity, heart rate, mood, sleep, skin and hair or menstrual cycles. Diagnosis may include an examination, thyroid blood tests and imaging. Treatment depends on the type and cause and may involve medication, radioiodine therapy, beta-blockers or surgery. [1]
If symptoms persist or your neck’s appearance changes, arrange a thyroid evaluation. [1]
Frequently Asked Questions
What is thyroid disease?
Thyroid disease is a general term for conditions that keep the thyroid from making the right amount of hormones. The two main types are hypothyroidism and hyperthyroidism.
What is the difference between hypothyroidism and hyperthyroidism?
Hypothyroidism means the thyroid is underactive and makes too little hormone. Hyperthyroidism means it is overactive and makes too much. Symptoms often reflect these opposite metabolic effects.
What are common symptoms of an underactive thyroid?
Symptoms may include a slower heart rate, fatigue, unexplained weight gain, cold sensitivity, dry skin, dry coarse hair, depressed mood and heavy menstrual periods.
What are common symptoms of an overactive thyroid?
Symptoms may include a faster heart rate, trouble sleeping, unexplained weight loss, heat sensitivity, clammy or sweaty skin, anxiety, irritability, nervousness and irregular or absent periods.
What do T3, T4 and TSH mean?
T3 and T4 are thyroid hormones. TSH stands for thyroid-stimulating hormone and is one of the blood tests used to assess thyroid function.
Can thyroid disease cause a lump or swelling in the neck?
Both hypothyroidism and hyperthyroidism can cause an enlarged thyroid, called a goiter. Thyroid nodules can also occur and may be assessed with ultrasound or other imaging.
How is thyroid disease diagnosed?
Diagnosis may include questions about symptoms and medical history, a physical examination, blood tests for TSH, T3, T4 and thyroid antibodies, thyroid ultrasound and sometimes nuclear medicine imaging.
Is thyroid disease usually lifelong?
Thyroid disease is often lifelong, although some conditions, including postpartum thyroiditis, are usually temporary. A provider can explain the expected course for a specific diagnosis.
Can thyroid disease be prevented?
Most thyroid disease is not preventable because genetics and autoimmune conditions cause many cases. Some problems related to iodine excess or deficiency may be preventable in certain circumstances.
Can people live a normal life with thyroid disease?
Yes. People can usually live a normal life with thyroid disease when they consistently manage the condition, attend monitoring visits and adjust treatment as needed.
When should I seek care for possible thyroid disease?
See a healthcare provider for symptoms of hypothyroidism or hyperthyroidism or a change in the appearance of your neck. Urgent care is appropriate for severe or rapidly worsening symptoms.
Related reading
Understanding the Endocrine System: Functions, Organs, and Health
Graves’ Disease: How an Overactive Immune System Drives an Overactive Thyroid
Thyroid Nodules: Symptoms, Causes, Diagnosis and Treatment — What You Need to Know
Goiter: What a Neck Bulge Means, the 7 Causes, and How Treatment Protects Your Thyroid
Radioactive Iodine Therapy: A Targeted Treatment for Thyroid Conditions
What Is Congenital Hypothyroidism? The Thyroid Hormone Deficiency Babies Are Born With, Explained
Thyroid Cancer: Symptoms, Causes, Diagnosis and Treatment — What You Need to Know
Thyroid Antibodies Test: TPO, Tg, TSI and TRAb Levels Explained explains the blood test that shows whether autoimmune thyroid antibodies are present.
Thyroid Panel Blood Test: TSH, T3, T4 and Antibodies Explained explains the thyroid blood tests used to diagnose and monitor this condition.
References
Cleveland Clinic. Thyroid Disease: What It Is, Causes, Symptoms & Treatment. Cleveland Clinic. Last updated March 25, 2024. https://my.clevelandclinic.org/health/diseases/8541-thyroid-disease
Zenaw A, Chane E, Biadgo B, et al. Global prevalence of thyroid dysfunction among pregnant women, 2003-2024: a systematic review and meta-analysis. Womens Health (Lond). 2026;22:17455057261490607. PMID 42751815. https://doi.org/10.1177/17455057261490607
Amirabadizadeh A, Ghorbani A, Azizi F, et al. Exploring the bidirectional association between thyrotropin and thyroid hormones in type 2 diabetes: a systematic review and meta-analysis. J Diabetes Metab Disord. 2025;24(1):98. PMID 40207063. https://doi.org/10.1007/s40200-025-01612-w
Li RC, Chen YY, Huang AF, et al. Thyroid dysfunction risk in systemic lupus erythematosus: a systematic review of case-control studies. Front Immunol. 2026;17:1810304. PMID 42718833. https://doi.org/10.3389/fimmu.2026.1810304
Disclaimer
This article is for general educational purposes and is not a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified healthcare professional with any questions about a medical condition or treatment.
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