Causes, Symptoms and Treatments

Learn more about the symptoms, causes, diagnosis, and drugs used to treat Hypothyroidism.

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Navin Khosla NowPatientGreen tick
Updated on 7 Jun 2024

Hypothyroidism, also known as underactive thyroid disease, is a common disorder that occurs when the thyroid gland doesn’t produce enough thyroid hormone. The thyroid gland, located in the front of the neck, plays a vital role in regulating metabolism and controlling various bodily functions. When there are low levels of thyroid hormone, the body’s processes slow down, leading to a range of symptoms and potential health complications.

Symptoms of Hypothyroidism

The symptoms of hypothyroidism can vary from person to person, and they often develop gradually over time. Many of the symptoms of an underactive thyroid are similar to those of other conditions, so it can be confused for something else. Also, symptoms can develop slowly and you may not realize you have a medical problem for several years. Some common symptoms include:

  • Fatigue: Individuals with hypothyroidism often experience excessive tiredness and lack of energy.
  • Weight gain: Unexplained weight gain or difficulty losing weight can be a symptom of an underactive thyroid.
  • Sensitivity to cold: People with hypothyroidism may feel cold more easily than others.
  • Dry skin and hair: Hypothyroidism can cause dryness and brittleness of the skin and hair.
  • Constipation: Sluggish bowel movements and difficulty passing stool are common symptoms.
  • Depression: Hypothyroidism can contribute to feelings of depression and mood changes.
  • Muscle weakness and joint pain: Individuals may experience muscle aches, stiffness, and weakness.
  • Menstrual irregularities: Women with hypothyroidism may have heavier or irregular menstrual periods.
  • Hoarse voice: Changes in the voice, including hoarseness, can occur due to an underactive thyroid.
  • Memory problems in elderly people: Hypothyroidism can affect cognitive function, leading to memory and concentration issues
  • Loss of sex drive
  • Pain, numbness, or tingling sensation in the hand and fingers
  • Slower growth and development in children
  • Puberty may start earlier than normal in teenagers

If an underactive thyroid is not treated you may develop anemia, hearing loss, a puffy-looking face, a slow heart rate, or a hoarse or low-pitched voice. This is unlikely however as hypothyroidism is often diagnosed before serious symptoms appear. It’s important to remember that symptoms can be non-specific and easily attributed to other conditions. Thus, it is crucial to consult a healthcare provider for an accurate diagnosis.

Causes of Hypothyroidism

Several factors can contribute to the development of hypothyroidism. The most common cause of hypothyroidism is an autoimmune disorder called Hashimoto’s disease, in which the immune system mistakenly attacks the thyroid gland (the thyroid gland is part of the endocrine system). Other causes include:

  • Thyroid surgery: Removal of all or part of the thyroid gland can lead to an underactive thyroid.
  • Radiation treatment: Treatment for certain cancers, such as lymphoma, can damage the thyroid gland and impair its hormone production, or treatment for an overactive thyroid gland using radioactive iodine therapy or surgery
  • Medications: Certain medications, such as amiodarone and lithium, can interfere with thyroid hormone production. Speak to your healthcare provider about your medication before you start taking it, especially if you have hypothyroidism
  • Congenital hypothyroidism: Some infants are born with an underdeveloped or nonfunctioning thyroid gland, leading to hypothyroidism from birth.
  • Iodine deficiency: Inadequate intake of iodine, a mineral necessary for thyroid hormone synthesis, can result in an underactive thyroid.
  • Pituitary or hypothalamic disorders: Problems with the pituitary gland or hypothalamus can disrupt the production of thyroid-stimulating hormone (TSH), usually because of non-cancerous tumors of the pituitary gland
  • Thyroiditis: Where the thyroid gland becomes inflamed. This can happen after pregnancy (postpartum thyroiditis) or may be due to an infection or an autoimmune disorder. Thyroiditis can cause the thyroid gland to release all of its thyroid hormones at once, causing hyperthyroidism (a sudden increase in thyroid activity). The thyroid then becomes underactive afterward
  • Inherited thyroid disorder: Some babies are born with no or an underactive thyroid gland. The reason for this is unclear
  • Pregnancy: Hypothyroidism may develop during or after pregnancy. If untreated during pregnancy, it can increase the risk of premature delivery, pregnancy loss, and preeclampsia which can cause a serious increase in blood pressure during the last 3 months of pregnancy. Hypothyroidism can also affect the development of the fetus
  • Lack of iodine: The thyroid needs iodine to make thyroid hormones, and too little iodine can cause hypothyroidism. Too much iodine can make the condition worse in people who already have hypothyroidism. Thyroid problems in the United States have almost been eliminated by adding iodine to table salt

Hypothyroidism risk factors

Older women are more likely to develop hypothyroidism. Hypothyroidism is also more likely to develop if you have a family history of thyroid disease. Other risk factors include:

  • Being white or Asian
  • Age
  • Having prematurely greying hair
  • Multiple sclerosis
  • Rheumatoid arthritis
  • Addison’s disease
  • Pernicious anemia, or vitiligo
  • Bipolar disorder
  • Down syndrome
  • Turner syndrome
  • Autoimmune diseases, such as type 1 diabetes or celiac disease
  • Recent treatment for hyperthyroidism
  • Thyroid surgery

Diagnosis of Hypothyroidism

It is important that an underactive thyroid is diagnosed as soon as possible. To diagnose low levels of thyroid-producing hormones, healthcare providers will typically perform a thorough evaluation, including a medical history review, physical examination, and blood tests. Blood tests can assess TSH levels (thyroid-stimulating hormone) and thyroid hormones (T4 (thyroxine) and T3 (triiodothyronine)) to determine if thyroid function is impaired. Imaging tests, such as thyroid ultrasound or scans, may also be conducted to evaluate the structure and function of the thyroid gland. Therefore, you should see your healthcare provider for a blood test if you have symptoms of hypothyroidism. Your healthcare provider may recommend you have blood tests every so often to check whether you develop an underactive thyroid.

A thyroid antibody test may also be recommended after a thyroid function test to help diagnose autoimmune thyroid conditions, such as Hashimoto’s thyroiditis. A thyroid antibody test will only be carried out if your healthcare provider suspects you have an autoimmune thyroid problem.

Treating Hypothyroidism

Certain conditions such as hyperthyroidism, thyroid nodules, goiters (enlarged thyroid), and thyroid cancer may be treated by fully or partially removing the thyroid gland.

You may not require any treatment for hypothyroidism if your symptoms are mild or you do not have any symptoms even if your blood tests show you may have an underactive thyroid. In these cases, your healthcare provider will monitor your thyroid levels over several months and prescribe levothyroxine if symptoms do develop.

Treatment for hypothyroidism (an underactive thyroid) involves hormone replacement therapy with synthetic thyroid hormones. The most commonly prescribed medication is levothyroxine, which provides the body with the necessary thyroid hormone which your thyroid gland does not produce enough of. The dosage of levothyroxine is initially adjusted based on regular blood tests to ensure that hormone levels are within the optimal range. This may take some time to get right. Once your correct dose has been found, you will normally have an annual blood test to monitor your thyroid levels. You will normally need to take levothyroxine for the rest of your life as an underactive thyroid is a lifelong condition.

Levothyroxine is normally taken as a tablet, but those with very severe hypothyroidism will first need to be treated with intravenous levothyroxine in the hospital. You may begin treatment on a low dose of levothyroxine. Your dose may be increased, depending on how you respond to this treatment. You may find you start to feel better quite soon after starting treatment, or you may not notice any improvement in your symptoms for a few months.

Levothyroxine should be taken at the same time each day. You will normally be recommended to take your tablets in the morning, even though you may prefer to take your tablets at night. The effectiveness of your levothyroxine treatment may be affected if you are taking other medication, supplements, or even food. Levothyroxine should be taken with a glass of water on an empty stomach and you should avoid eating anything 30 minutes before or after taking your tablets.

If you miss a dose of your levothyroxine, you should take it as soon as you remember, if you have only missed it by a few hours of your normal time. If you have forgotten to take it until later than this time, skip the missed dose and take your next dose at your normal time, unless otherwise advised by a healthcare professional.

Levothyroxine doesn’t have any side effects normally, as the tablets are replacing a missing hormone. Side effects may occur however if you take too much levothyroxine. You may experience side effects such as chest pain, sweating, headaches, nausea, and diarrhea. Also, you should tell your healthcare provider if you develop any new symptoms, or if your symptoms get worse or do not improve while taking levothyroxine.

Suppressing thyroid-stimulating hormone (TSH) through the use of high-dose thyroid replacement therapy is not recommended in most cases, as it carries a risk of causing adverse side effects, such as atrial fibrillation (an irregular and unusually fast heart rate), strokes, osteoporosis or fracture. This type of treatment may however sometimes be recommended when a person has a history of thyroid cancer and there’s an increased risk of it happening again.

It is important to take thyroid medication consistently and as prescribed by a healthcare provider. Regular follow-up appointments are necessary to monitor thyroid function and adjust medication dosages if needed. With appropriate treatment, individuals with hypothyroidism can effectively manage their condition and alleviate symptoms.

Complications and Long-Term Outlook

If left untreated, hypothyroidism can lead to various other health problems. These may include:

  • Cardiovascular issues: Hypothyroidism can contribute to high cholesterol levels, increasing the risk of heart disease and heart failure
  • Myxedema: Severe untreated hypothyroidism can result in a life-threatening condition called myxedema coma, characterized by extreme slowing of your body’s functions
  • Mental health concerns: Untreated hypothyroidism can impact mental well-being, leading to depression, anxiety, and cognitive impairments.
  • Infertility and pregnancy complications: Hypothyroidism can interfere with fertility and increase the risk of complications during pregnancy, such as miscarriage and preterm birth.
  • Underactive thyroid and pregnancy: An underactive thyroid should be treated before you become pregnant. Tell your healthcare provider if you’re pregnant or planning to become pregnant if you have hypothyroidism
  • Hypothyroidism may also contribute to high cholesterol levels. Low levels of thyroid-producing hormones, such as triiodothyronine and thyroxine, can cause high cholesterol and atherosclerosis, which may lead to angina, heart attacks, or other serious heart-related problems

However, with appropriate treatment and regular monitoring, individuals with hypothyroidism can lead healthy and fulfilling lives. It is crucial to adhere to medication regimens, attend scheduled check-ups, and communicate any concerns or changes in symptoms to healthcare providers.


Hypothyroidism is a common condition characterized by an underactive thyroid gland, resulting in insufficient production of thyroid hormones. The symptoms of hypothyroidism can vary but often include fatigue, weight gain, sensitivity to cold, and changes in skin and hair. Causes of hypothyroidism range from autoimmune disorders to medication side effects and iodine deficiency. Early diagnosis and proper treatment with thyroid hormone replacement therapy can effectively manage the condition and alleviate symptoms. Regular follow-up with healthcare providers is essential to ensure optimal thyroid function and overall well-being.


NHS – Hypothyroidism Diagnosis

Medical News Today – What is Hypothyroidism?

MayoClinic – Hypothyroidism Symptoms and Causes

WebMD – Hypothyroidism Symptoms and Causes

Thyroid.org – Hypothyroidism

Medical Disclaimer

NowPatient has taken all reasonable steps to ensure that all material is factually accurate, complete, and current. However, the knowledge and experience of a qualified healthcare professional should always be sought after instead of using the information on this page. Before taking any drug, you should always speak to your doctor or another qualified healthcare provider.

The information provided here about medications is subject to change and is not meant to include all uses, precautions, warnings, directions, drug interactions, allergic reactions, or negative effects. The absence of warnings or other information for a particular medication does not imply that the medication or medication combination is appropriate for all patients or for all possible purposes.

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