Hypothyroidism
Hypothyroidism, also called underactive thyroid, occurs when your thyroid gland doesn’t produce enough thyroid hormones to meet your body’s needs. This common condition affects nearly 5 out of 100 Americans and can slow down many of your body’s functions, causing fatigue, weight gain, and other symptoms that develop gradually over time.
Table of contents
- What Is Hypothyroidism?
- Types of Hypothyroidism
- How Common Is Hypothyroidism?
- Who Is More Likely to Develop Hypothyroidism?
- What Are the Symptoms?
- What Causes Hypothyroidism?
- What Other Problems Can Hypothyroidism Cause?
- How Is Hypothyroidism Diagnosed?
- How Is Hypothyroidism Treated?
- Living with Hypothyroidism
- What Can You Expect Over the Long Term?
What Is Hypothyroidism?
Hypothyroidism is a condition where the thyroid gland doesn’t make enough thyroid hormones to meet your body’s needs.[1] The thyroid is a small, butterfly-shaped gland located in the lower front of your neck.[4] This gland makes hormones that control the way your body uses energy, affecting nearly every organ in your body, including how your heart beats.[1]
Thyroid hormones affect your breathing, heart rate, weight, digestion, and moods.[5] Without enough thyroid hormones, many of your body’s functions slow down.[1] As your metabolism (the process by which your body converts food into energy) slows down, you may notice changes such as feeling colder, tiring more easily, and gaining weight unexpectedly.[3]
- Thyroid gland
- Neck
Types of Hypothyroidism
Hypothyroidism is primarily categorized into different types based on where the problem originates.[6] Understanding these types helps doctors determine the best treatment approach.
Primary hypothyroidism is the most common type. It occurs when your thyroid gland itself cannot produce adequate amounts of thyroid hormone.[6] In this type, your thyroid is directly impacted and makes low levels of thyroid hormones. In response, your pituitary gland (a pea-sized gland at the base of your brain) makes more thyroid stimulating hormone (TSH).[3] Autoimmune conditions like Hashimoto’s disease can cause it, or it can happen after thyroid gland surgery or radiation therapy.[3]
Secondary hypothyroidism is rare and occurs when you have an underactive pituitary gland. This type prevents your pituitary gland from sending TSH to your thyroid gland.[3] In this case, the thyroid gland functions normally, but hypothyroidism results from abnormal pituitary gland function.[6]
Tertiary hypothyroidism happens when your hypothalamus (a structure in your brain that helps keep your body balanced) doesn’t make enough thyrotropin-releasing hormone (TRH). As a result, your pituitary gland can’t make enough TSH.[3]
Subclinical hypothyroidism, also known as mild thyroid failure, happens when you have slightly elevated TSH levels, but all other thyroid hormone levels are within a typical range. This type usually goes away on its own in about three months.[3]
How Common Is Hypothyroidism?
Nearly 5 out of 100 Americans ages 12 years and older have hypothyroidism, although most cases are mild or have few obvious symptoms.[1] Clinical hypothyroidism affects one in 300 people in the United States.[7] The condition is most common among females over age 60, particularly after menopause.[3]
Who Is More Likely to Develop Hypothyroidism?
Women are much more likely than men to develop hypothyroidism.[1] The disease is also more common among people older than age 60.[1]
You are more likely to have hypothyroidism if you:[1][5]
- Had a thyroid problem before, such as a goiter (an enlarged thyroid)
- Had surgery or radioactive iodine to correct a thyroid problem
- Received radiation treatment to the thyroid, neck, or chest
- Have a family history of thyroid disease
- Were pregnant in the past 6 months
- Have Turner syndrome, a genetic disorder that affects females
- Have pernicious anemia, a condition where the body cannot make enough healthy red blood cells because it does not have enough vitamin B12
- Have Sjögren’s syndrome, a disease that causes dry eyes and mouth
- Have type 1 diabetes
- Have rheumatoid arthritis, an autoimmune disease that affects the joints
- Have lupus, a chronic autoimmune disease
Your thyroid is also more likely to be underactive if you have other health problems, including celiac disease.[1]
What Are the Symptoms?
The symptoms of hypothyroidism depend on the severity of the condition. Problems tend to develop slowly, often over several years.[2] At first, you may barely notice the symptoms of hypothyroidism, such as fatigue and weight gain. Or you may think they are just part of getting older.[2] Because hypothyroidism develops slowly, many people don’t notice symptoms of the disease for months or even years.[5]
As your metabolism continues to slow, you may develop more obvious problems. Hypothyroidism symptoms may include:[2][3][5]
- Tiredness or fatigue
- More sensitivity to cold temperatures
- Constipation
- Dry skin and dry, coarse hair
- Weight gain
- Puffy face
- Hoarse voice
- Muscle weakness, aches, tenderness and stiffness
- Joint and muscle pain
- Menstrual cycles that are heavier than usual or irregular
- Thinning hair
- Slowed heart rate
- Depression and anxiety
- Memory problems or brain fog (forgetfulness or difficulty concentrating)
- Decreased sweating
- Elevated blood cholesterol levels
- Numbness or tingling in your hands
- Physical changes in your face (drooping eyelids, puffiness around your eyes)
- Fertility problems in women
- Goiter (an enlarged thyroid that may cause your neck to look swollen and sometimes cause trouble with breathing or swallowing)
If you develop any signs of hypothyroidism, let your healthcare provider know. They can run tests to confirm a diagnosis.[3]
What Causes Hypothyroidism?
Hypothyroidism has several causes. In the United States, autoimmune thyroid disease is the most common cause of hypothyroidism, but globally, lack of iodine in the diet is the most common cause.[6]
Hashimoto’s disease is the most common cause of hypothyroidism. It is an autoimmune disorder where your immune system attacks your thyroid.[4][5] This condition is also called Hashimoto’s thyroiditis.[4]
Other causes of hypothyroidism include:[3][5]
- Thyroiditis, which is inflammation of the thyroid
- Congenital hypothyroidism (hypothyroidism that is present at birth), including being born with no thyroid gland or a thyroid gland that doesn’t work properly
- Surgical removal of part or all of the thyroid
- Radiation treatment of the thyroid
- Certain medicines, including lithium, thalidomide and amiodarone
- In rare cases, a pituitary disease
- Too much or too little iodine in your diet
What Other Problems Can Hypothyroidism Cause?
Hypothyroidism may not cause noticeable symptoms in its early stages. Over time, hypothyroidism that isn’t treated can lead to other health problems, such as high cholesterol and heart problems.[2] Hypothyroidism can contribute to high cholesterol.[5]
In rare cases, untreated hypothyroidism can cause myxedema coma. This is a condition in which your body’s functions slow down to the point that it becomes life-threatening.[5] Left untreated over long periods of time, hypothyroidism can become life-threatening.[3]
During pregnancy, hypothyroidism can cause complications, such as premature birth, high blood pressure in pregnancy, and miscarriage. It can also slow the baby’s growth and development.[5]
A persistently increased TSH can lead to increased levels of cholesterol, which can cause heart disease. Similarly, a persistently low TSH can lead to an increased risk for atrial fibrillation (irregular heartbeat), which causes the heart to beat irregularly and increases the risk of stroke.[13]
How Is Hypothyroidism Diagnosed?
The symptoms of hypothyroidism can be different from person to person and often look like symptoms of other health problems. Because of that, a diagnosis of hypothyroidism doesn’t rely on symptoms alone.[8] Your health care provider may use many tools to make a diagnosis.[5]
The only way to know for sure whether you have hypothyroidism is with a simple blood test for TSH.[4] The first blood test typically done to diagnose hypothyroidism measures the level of thyroid-stimulating hormone (TSH) in the blood. If it’s high, the test is done again, along with a blood test for the thyroid hormone T-4.[8] If the results show that TSH is high and T-4 is low, then the diagnosis is hypothyroidism.[8]
Your health care provider may also perform:[5]
- A medical history, including asking about your symptoms
- A physical exam
- Thyroid tests, such as TSH, T3, T4, and thyroid antibody blood tests
- Imaging tests, such as a thyroid scan, ultrasound, or radioactive iodine uptake test
In some cases, the thyroid hormone T-3 may be measured as well.[8] A serum TSH level is typically used to assess for primary hypothyroidism in most patients initially.[6] Characteristic laboratory findings of hypothyroidism include elevated TSH levels and low free T4 levels.[6]
How Is Hypothyroidism Treated?
Treatment for hypothyroidism usually includes taking the thyroid hormone medicine levothyroxine every day.[8] This medicine is taken by mouth and returns hormone levels to a healthy range, eliminating symptoms of hypothyroidism.[8] The treatment for hypothyroidism is medicine to replace the hormone that your own thyroid can no longer make.[5]
In general, hypothyroidism is very treatable. Most people can manage the condition with medication and regular follow-up visits with their endocrinologist.[3] Symptom relief and normalized thyroid-stimulating hormone levels are achieved with levothyroxine replacement therapy.[7]
You’ll likely start to feel better one or two weeks after you begin treatment.[8] However, thyroid hormone medication is a slow-acting drug, so it may take several months for your symptoms to reduce.[16] If your TSH level was very high before starting treatment with levothyroxine, it may take longer for you to feel well again.[16]
About 6 to 8 weeks after you start taking the medicine, you will get a blood test to check your thyroid hormone level. Your health care provider will adjust your dose if needed. Each time your dose is adjusted, you’ll have another blood test.[5] Blood tests are not usually offered until three months after starting or changing your dose as your thyroxine levels will still be adjusting.[16]
After dosage stabilization, patients can be monitored with annual or semiannual clinical evaluations and TSH monitoring.[14] Usually, your TSH will be measured every three months until the level has stabilized and then every 12 months after that.[16]
Levothyroxine is best taken in the morning, with water, on an empty stomach, at least half an hour before eating and drinking.[16] Certain medications and supplements can affect how well the body absorbs levothyroxine. For this reason, you should take your levothyroxine at least four hours apart from calcium, iron, cholesterol-lowering drugs and multivitamin tablets.[16]
Women with hypothyroidism who become pregnant should increase their weekly dosage by 30% up to nine doses per week (that is, take one extra dose twice per week), followed by monthly evaluation and management.[7]
Living with Hypothyroidism
While medication is essential, certain lifestyle measures can improve the way your immune system functions and help ease the symptoms of hypothyroidism.[22] Taking your medication consistently really matters. Taking your levothyroxine each day is very important, and forgetting to do this is one of the main reasons why people don’t feel well.[16]
Many find having simple systems in place helpful, such as setting a reminder on your phone and using a pillbox or medication organizer.[16] If you forget to take the occasional dose, it won’t make an immediate difference as your body has a big reservoir of levothyroxine. However, you should take the dose as soon as you remember and try not to miss doses too often.[16]
Store your levothyroxine carefully. Levothyroxine loses its potency over time and should be stored at room temperature away from moisture, heat and direct sunlight.[16]
Eating a well-balanced diet may be helpful to manage hypothyroidism effectively. By planning your meals ahead of time, you can avoid fast foods and less healthy options. Instead, focus on whole, unprocessed foods and incorporate lean proteins, fruits, vegetables, and whole grains into your meals.[18] Generally, there’s no diet to help with underactive thyroid, and eating a balanced diet will keep the thyroid healthy.[20]
Be aware that caffeine can stop your body absorbing levothyroxine properly, so it’s important to take your medication at least 30 minutes before having coffee or tea.[16] Too much fiber in your diet can keep the body from absorbing the medicine.[20]
Regular physical activity boosts metabolism and helps regulate hormone levels. Aim for a balanced exercise routine that includes cardiovascular workouts, strength training and flexibility exercises for optimal thyroid health.[21] Exercise can help with many side effects of hypothyroidism, including bad mood, low energy, and weight gain.[22]
Chronic stress can negatively impact thyroid function. Engage in stress-relieving activities like yoga, meditation, deep breathing exercises or hobbies to maintain healthy cortisol levels and support your thyroid.[21] To manage your mood, do something relaxing every day for at least 10 minutes.[22]
Quality sleep is crucial for overall health, including thyroid function. Aim for 8 hours of sleep every night to support hormone production and regulate metabolism.[21][22] To ensure your body has a chance to rest and recover, hit the hay and wake up at roughly the same times most days, and make sure your bedroom is dark, quiet, and cool.[22]
What Can You Expect Over the Long Term?
There is no cure for hypothyroidism, and most patients have it for life.[4] There are exceptions: many patients with viral thyroiditis have their thyroid function return to normal, as do some patients with thyroiditis after pregnancy.[4]
It’s important to tell your family members about your condition. Because thyroid disease runs in families, you should explain your hypothyroidism to your relatives and encourage them to get periodic TSH tests.[4] Tell your other doctors and your pharmacist about your hypothyroidism and the drug and dose with which it is being treated.[4] If you start seeing a new doctor, tell the doctor that you have hypothyroidism and you need your TSH tested every year.[4]
If you develop new symptoms, it’s important to get an evaluation.[3] Patients with persistent symptoms after adequate levothyroxine dosing should be reassessed for other causes or the need for referral.[7]
