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Overview
What Is Hypothyroidism?
Hypothyroidism is an underactive thyroid that does not produce enough thyroid hormone. This hormone helps regulate metabolism, which affects how the body uses energy and carries out many everyday functions. It can affect people of any age, including during pregnancy. Hypothyroidism is usually manageable with medical care and the right treatment.
Symptoms
Symptoms of Hypothyroidism
Symptoms of hypothyroidism often develop gradually and may be mild at first. They can differ from person to person, and having one or more of these symptoms does not confirm the diagnosis. Blood tests are needed to determine whether an underactive thyroid is the cause.
- Slowed heart rate (bradycardia)
- Constipation
- Dry skin
- Fatigue
- Feeling unusually cold
- Hair thinning
- Heavier menstrual periods
- Irregular menstrual periods
- Low mood
- Muscle aches
- Trouble concentrating
- Unexplained weight gain
Causes
Causes of Hypothyroidism
Hypothyroidism occurs when the thyroid gland cannot make enough hormone or when signals from the brain do not adequately stimulate the thyroid. The cause may involve the immune system, thyroid damage, medicines, iodine imbalance, or a problem affecting the pituitary gland or hypothalamus.
- Hashimoto’s disease is an autoimmune condition in which the immune system attacks the thyroid and gradually reduces hormone production.
- Thyroiditis, or inflammation of the thyroid, can temporarily or permanently reduce thyroid hormone production.
- Thyroid surgery may remove enough thyroid tissue that the remaining gland cannot make sufficient hormone.
- Radioactive iodine treatment or radiation to the neck can damage thyroid cells and lead to an underactive thyroid.
- Certain medicines can interfere with thyroid hormone production or release.
- Congenital thyroid problems may cause a baby to have an absent, abnormal, or poorly functioning thyroid gland.
- Severe iodine deficiency or excessive iodine intake can interfere with normal thyroid hormone production.
- Disease of the pituitary gland or hypothalamus can reduce the signals needed to stimulate the thyroid.
Risk Factors
Risk Factors for Hypothyroidism
Risk factors are circumstances that may raise the likelihood of developing hypothyroidism, but they do not mean that someone will definitely develop it. Some factors cannot be changed, while others relate to medical treatment, medicines, or iodine exposure.
| Risk factor group | Examples |
|---|---|
| Personal or family factors | A family history of thyroid disease or an autoimmune condition can increase susceptibility. |
| Age and sex | Risk generally increases with older age, and hypothyroidism is more common in females. |
| Pregnancy and recent childbirth | Pregnancy or the period after giving birth can be associated with thyroid changes. |
| Previous thyroid treatment | Thyroid surgery, radioactive iodine, or radiation to the neck can increase risk. |
| Medicines | Some thyroid-affecting medicines may interfere with hormone production or release. |
| Iodine exposure | Iodine deficiency or excess can disrupt normal thyroid function. |
Complications
Complications of Hypothyroidism
Many complications of hypothyroidism can be prevented or managed when thyroid hormone levels are monitored and treated appropriately. Problems are more likely when the condition is untreated, severe, or not adequately controlled.
- High cholesterol can develop or worsen when thyroid hormone levels are low.
- Cardiovascular disease risk may increase because of changes in cholesterol and heart function.
- Fertility problems may occur when untreated hypothyroidism disrupts reproductive function.
- Pregnancy complications can occur, including effects on the pregnant person or developing baby.
- Peripheral nerve problems may cause numbness, tingling, or weakness in the hands or feet.
- Depression or cognitive changes, such as problems with memory or concentration, may occur.
- Severe untreated hypothyroidism can progress to myxedema coma, a rare medical emergency.
Urgent warning
Recognize severe symptoms
Extreme sleepiness, confusion, very low body temperature, slowed breathing, or loss of consciousness in someone with severe hypothyroidism requires emergency medical care.
Diagnosis
Diagnosis of Hypothyroidism
Diagnosis usually begins with a medical history and physical examination, followed by blood tests. The main tests measure thyroid-stimulating hormone (TSH) and free thyroxine (free T4), which show how the thyroid and its control system are functioning.
How Thyroid Blood Tests Are Interpreted
In primary hypothyroidism, the typical pattern is a high TSH level with a low free T4 level. Clinicians may repeat testing because results can be affected by illness, medicines, timing, laboratory differences, or recent changes in thyroid function. Subclinical hypothyroidism means that TSH is elevated while free T4 remains normal. Treatment decisions depend on the degree of abnormality, symptoms, age, pregnancy status, thyroid antibodies, and other health factors.
Treatment & Management
Hypothyroidism Treatment and Management
Levothyroxine, a synthetic form of thyroid hormone, is the standard first-line hypothyroidism treatment for most people. The dose is individualized based on factors such as test results, age, symptoms, pregnancy, and other medical conditions.
- Take levothyroxine exactly as prescribed by your clinician.
- Take the medicine consistently in relation to food and other medicines, following the instructions provided.
- Have your TSH checked after a dose change so the treatment can be adjusted safely.
- Continue periodic thyroid monitoring even after your dose becomes stable.
- Discuss pregnancy, plans to become pregnant, or major health changes with your clinician because treatment needs may change.
Outlook and Prognosis
Outlook and Prognosis
Hypothyroidism is often a chronic condition, but it is usually well controlled with the right thyroid hormone dose. Symptoms may improve over several weeks rather than immediately after treatment begins.
Regular blood tests help maintain the correct dose over time. Treatment needs can change with pregnancy, aging, weight changes, new medicines, or changes in thyroid function, so ongoing follow-up is important.
When Should You See a Doctor
When Should You See a Doctor?
- Contact a clinician for persistent or worsening symptoms that could be related to an underactive thyroid.
- Ask for medical evaluation if you notice new swelling in the neck.
- Discuss testing with a clinician if you have a strong family or personal history of thyroid disease.
- Contact a clinician if you are pregnant or planning to become pregnant.
- Follow up with a clinician about abnormal thyroid test results.
- Ask for advice if you have problems taking or tolerating prescribed thyroid medicine.
Seek urgent care
Do not wait for severe symptoms
Contact emergency services for severe confusion, extreme drowsiness, very low body temperature, slowed breathing, chest pain, or loss of consciousness.
Branches
1 topic
Hypothyroidism
Endocrinology & Metabolic Diseases
Tests & Procedure
1 topic
Hypothyroidism
Tsh Blood Test
Symptoms
1 topic
Hypothyroidism
Fatigue
