Underactive thyroid

Underactive thyroid - Illnesses & conditions | NHS inform Home Illnesses and conditions Symptoms and self-help Tests and treatments Healthy living Care, support and rights Scotlands Service Directory 0 Home Illnesses and conditions Glands Underactive thyroid Underactive thyroid About underactive thyroids Symptoms of an underactive thyroid Causes of an underactive thyroid Diagnosing an underactive thyroid Treating an underactive thyroid Complications of an underactive thyroid About underactive thyroids An underactive thyroid gland (hypothyroidism) is where your thyroid gland doesnt produce enough hormones. Common signs of an underactive thyroid are tiredness, weight gain and feeling depressed. An underactive thyroid can often be successfullytreated by taking daily hormone tablets to replace the hormonesyour thyroid isnt making. Theres no way of preventing an underactive thyroid. Most cases are caused either by the immune system attacking the thyroid gland and damaging it,orby damage to the thyroid that occurs during some treatments for an overactive thyroidor thyroid cancer . Read more about the causesof an underactive thyroid When to see your GP Symptoms of an underactive thyroid are often similar to those of other conditions,and theyusually develop slowly, so you may not notice them for years. You should see your GP and ask to be tested for an underactive thyroid if you havesymptoms including: tiredness weight gain depression being sensitive tothe cold dry skin and hair muscle aches The only accurate way of finding out whether you have a thyroid problem is to haveathyroid function test, where a sample of blood is tested to measure yourhormone levels. Readmore about testing for an underactive thyroid Whos affected Both men and women can have an underactive thyroid, althoughits more commonin women. In the UK, it affects 15 in every 1,000 women and1 in 1,000 men. Children can also develop an underactive thyroid. Around 1 in 3,500 to 4,000 babiesare born with anunderactive thyroid (congenital hypothyroidism).All babies born in the UK are screened for congenital hypothyroidismusing a blood spot test when the baby is about 5 days old. Treating an underactive thyroid Treatment for an underactive thyroid involves taking dailyhormone replacement tablets, called levothyroxine,to raise yourthyroxine levels. Youll usually need treatment for the rest of your life. However, with proper treatment, you should be able to lead a normal, healthy life. If an underactive thyroid isnt treated, it can lead to complications, including heart disease ,goitre, pregnancy problems and a life-threatening condition called myxoedema coma (although this is very rare). Read more about treating an underactive thyroid and the complications of an underactive thyroid Symptoms of an underactive thyroid Many symptoms of an underactive thyroid (hypothyroidism) are the same as those of other conditions, so it can easily be confused for something else. Symptomsusually develop slowly and you may not realise you have a medical problem for several years. Common symptoms include: tiredness being sensitive to cold weight gain constipation depression slow movements and thoughts muscle aches and weakness muscle cramps dry and scaly skin brittle hair and nails loss of libido (sex drive) pain, numbness and a tingling sensation in the hand and fingers (carpal tunnel syndrome) irregular periodsor heavy periods Elderly people with an underactive thyroid may develop memory problems and depression. Children may experience slower growth and development. Teenagers may startpuberty earlier than normal. If you have any of these symptoms, see your GP and ask to be tested for an underactive thyroid. Read more about getting tested for an underactive thyroid If an underactive thyroid isnt treated Its unlikely that youd have many of the later symptoms of an underactive thyroid, because the condition is often identified before more serious symptoms appear. Later symptoms of an underactive thyroidinclude: a low-pitched and hoarse voice a puffy-looking face thinned or partly missing eyebrows a slow heart rate hearing loss anaemia Causes of an underactive thyroid An underactive thyroid (hypothyroidism) is when your thyroid gland doesnt produce enough of the hormone thyroxine (also called T4). Most cases of an underactive thyroid are caused by the immune system attacking the thyroid gland and damaging it, or by damage that occurs as a result oftreatments for thyroid cancer or an overactive thyroid . Immune system An underactive thyroid often occurs when the immune system, which usually fights infection, attacks the thyroid gland. This damages the thyroid, which means its not able to make enough of the hormone thyroxine,leading to the symptoms of an underactive thyroid . A condition called Hashimotos disease is the most common type of autoimmune reactionthatcauses an underactive thyroid. Its not clear what causes Hashimotos disease, but it runs in families. Its also common in people with another immune system disorder, such as type 1 diabetes and vitiligo. Previous thyroid treatment An underactive thyroid can also occur as a side effect or complication of previous treatment to the thyroid gland, such as surgery or a treatment called radioactive iodine therapy. These treatments are sometimes used for an overactive thyroid(where the thyroid glandproduces too much hormone) or thyroid cancer. Less common causes Worldwide,alack of dietaryiodine is a common cause of an underactive thyroid, because the body needs iodine to make thyroxine. However, iodine deficiency isuncommon in the UK. Babies are sometimes born with an underactive thyroid because the thyroid gland doesnt develop properly in the womb. This is called congenital hypothyroidism and isuncommon, affecting around 1 in 3,000 babies. Itsusually picked up during routine screening soon after birth. A problem with the pituitary gland could lead to an underactive thyroid.The pituitary gland sits at the base of the brain andregulates the thyroid. Therefore, damage to the pituitary gland may lead to an underactive thyroid. An underactive thyroid has also been linked tosome viral infections or somemedications used to treat other conditions, such as: lithium  a medication sometimes used to treat certain mental health conditions, including depression and bipolar disorder amiodarone  a medication sometimes used to treat irregular heartbeats (arrhythmias) interferons  a class of medication sometimes used to treat certain types of cancer and hepatitis C Speak to your GP or specialist if youre concerned that a medication youre taking may be affecting your thyroid hormone levels. Diagnosing an underactive thyroid Its very important that an underactive thyroid (hypothyroidism) is diagnosed as soon as possible. Low levels of thyroid-producing hormones, such astriiodothyronine (T3) and thyroxine (T4), can change the way the body processes fat. This can cause high cholesterol and atherosclerosis (clogging of the arteries) , which can potentially lead to serious heart-related problems, such as angina and heart attack . Therefore, you should see your GP and ask for a blood test if you repeatedly have symptoms of an underactive thyroid . Thyroid function test Ablood test measuring your hormone levels is the only accurate way to find out whethertheres a problem. The test, called a thyroid function test, looks at levels of thyroid-stimulating hormone (TSH) and thyroxine (T4) in the blood. Ahigh level of TSH and a low level ofT4 in the bloodcould mean you havean underactive thyroid. If your test results show raised TSH but normalT4, you may be at risk of developing an underactive thyroid in the future. Your GP may recommend that you have a repeat blood test every so often to see whether you eventually develop an underactive thyroid. Blood tests are also sometimes used for other measurements, such as checking the level of a hormone calledtriiodothyronine (T3). However, this isnt routine, because T3 levels can often remain normal, even if you have a significantly underactive thyroid. The Lab Tests Online UK website has more information about the different types of thyroid function tests . Referral Your GP may refer you to an endocrinologist (a specialist in hormone disorders) if you: are younger than 16 are pregnant or trying to get pregnant have just given birth have another health condition, such as heart disease , which may complicate your medication are taking a medication known to cause a reduction in thyroid hormones, such as amiodarone or lithium Treating an underactive thyroid An underactive thyroid (hypothyroidism) is usually treated by taking daily hormone replacement tablets called levothyroxine. Levothyroxinereplaces the thyroxine hormone, which your thyroid doesnt make enough of. Youll initially have regular blood tests until the correct doseof levothyroxine is reached. Thiscan take a little while to get right. You may start on a low dose of levothyroxine, which may be increased gradually, depending on how your body responds.Some people start to feel bettersoon after beginning treatment,while othersdont notice an improvement in their symptoms for several months Once youre taking the correct dose, youll usually have a blood test once a year to monitor your hormone levels. Ifblood tests suggest you may have an underactive thyroid, but you dont have any symptoms or theyre very mild, you may not need any treatment. In these cases, your GP will usually monitor your hormone levels every few months and prescribe levothyroxine if you develop symptoms. Taking levothyroxine If youre prescribed levothyroxine, you should take 1 tablet at the same time every day.Its usually recommended that you take the tablets in the morning, although some people prefer to take them at night. The effectiveness of thetablets can be altered by other medications, supplements or foods, so they should be swallowed with water on an empty stomach, and you should avoid eating for 30 minutes afterwards. If you forget to take a dose, take it as soon as you remember, if this is within a few hours of your usual time. If you dont remember until later than this, skip the dose and take the next dose at the usual time, unlessadvised otherwise by your doctor. An underactive thyroid is a lifelong condition, so youll usually need to take levothyroxine for the rest of your life. Side effects Levothyroxine doesnt usually have any side effects, because the tablets simply replace a missing hormone. Side effects usually only occur if youre taking too much levothyroxine. This can cause problems includingsweating, chest pain , headaches , diarrhoea and vomiting. Tell your doctor if you develop new symptoms while taking levothyroxine. You should also let them know if your symptoms get worse or dont improve. Combination therapy In the UK, combination therapy  using levothyroxine and triiodothyronine (T3) together  isnt routinely used because theres insufficient evidence to show its better than using levothyroxine alone (monotherapy). In most cases,suppressing thyroid-stimulating hormone (TSH) using high dose thyroid replacement therapy should be avoided because it carries a risk of causing adverse side effects, such as atrial fibrillation (an irregular and abnormally fast heart rate), strokes , osteoporosis and fracture. However, this type of treatment may sometimes be recommended in cases where a person has a history of thyroid cancer and theres a significant risk of it reoccurring. Complications of an underactive thyroid Several complications can occur if you have an underactive thyroid that isnt treated. Heart problems If you have an untreated underactive thyroid, your risk of developing cardiovascular disease is increased. This is because having low levels of the hormone thyroxine can lead to increased levels of cholesterol in your blood. High cholesterol can cause fatty deposits to build up in your arteries, restrictingthe flow of blood. Contact your doctor if youre being treated for an underactive thyroid and you develop chest pain , so that any problems can bedetected and treated, if necessary. Goitre Agoitreis an abnormal swelling of the thyroid gland that causes a lump to form in the throat. Goitres can develop in people with an underactive thyroidwhen the body tries tostimulate the thyroid to produce more thyroid hormones. Pregnancy complications If an underactive thyroid isnt treated during pregnancy, theres a risk of problems occurring. Theseinclude: pre-eclampsia  which can cause high blood pressure and fluid retentionin the mother and growth problems in the baby anaemia in the mother an underactive thyroid in the baby birth defects bleeding after birth problems with the babys physical and mental development premature birth or a low birthweight stillbirth or miscarriage These problems can usually be avoided with treatment under the guidance of a specialist in hormone disorders (an endocrinologist). Therefore, tell your GP if you have an underactive thyroid and youre pregnant or trying to get pregnant. Myxoedema coma In very rare cases, a severe underactive thyroid may lead to a life-threatening condition called myxoedema coma. This is where the thyroid hormone levels become very low, causing symptoms such as confusion, hypothermia and drowsiness. Myxoedema coma requires emergency treatment in hospital. Its usually treated with thyroid hormone replacement medication given directly into a vein. In some cases, other treatments such as breathing support, antibiotics and steroid medication ( corticosteroids ) are also required. Source: NHS 24 - Opens in new browser window Last updated: 01 December 2023 How can we improve this page? Help us improve NHS inform Thank You Your feedback has been received Dont include personal information e.g. name, location or any personal health conditions. Email Address e.g. you@example.com Message Maximum of 500 characters Send feedback Add this page to\n            Info For Me Also on NHS inform Overactive thyroid Other health sites Lab Tests Online: TSH Lab Tests Online UK: T4 test British Thyroid Foundation NHS inform About NHS inform Editorial policy Contact us Webchat Give feedback about NHS inform Info for Me tool Terms and conditions Privacy and cookies policy Freedom of information (FOI) Accessibility Other languages and formats  2023 NHS 24  v1.1.1.17852