Your thyroid may be small, but it plays an important role in how your body functions. Located at the front of your neck, this butterfly-shaped gland produces hormones that help regulate metabolism, body temperature and heart rate.
When your thyroid produces too little or too much hormone, it can affect your energy, weight, mood and overall health. Understanding the differences between hypothyroidism and hyperthyroidism can help you recognize symptoms, explore treatment options and know when to seek medical care.
What Does the Thyroid Gland Do?
The thyroid gland produces two main hormones, thyroxine (T4) and triiodothyronine (T3), which help regulate how your body uses energy. These hormones influence many important functions, including heart rate, digestion, body temperature and metabolism.
Thyroid function is controlled by thyroid-stimulating hormone (TSH), which is produced by the pituitary gland in the brain. TSH signals the thyroid to release hormones based on your body's needs.
When the thyroid does not produce the right amount of hormones, it can lead to two common conditions: hypothyroidism, an underactive thyroid, and hyperthyroidism, an overactive thyroid.
What Is Hypothyroidism?
Hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormone to meet the body's needs. This can slow down many bodily functions and cause symptoms that develop gradually over time.
One of the most common causes of hypothyroidism in the United States is Hashimoto's disease, an autoimmune condition in which the immune system attacks the thyroid gland and affects its ability to produce hormones.
Other possible causes include thyroid inflammation (thyroiditis), certain medications, previous thyroid surgery and radioactive iodine treatment. Iodine deficiency can also cause hypothyroidism, although it is uncommon in the United States.
Thyroid disorders are more common in women and older adults. Pregnancy and the postpartum period can also affect thyroid function, making evaluation and monitoring important for some patients.
Common Symptoms of Hypothyroidism
Symptoms of an underactive thyroid can vary from person to person and may develop slowly. Some people experience few noticeable symptoms, especially in the early stages.
Common symptoms include:
- Persistent fatigue or low energy
- Unexplained weight gain
- Increased sensitivity to cold temperatures
- Dry skin or thinning hair
- Constipation
- Depression or changes in mood
- Difficulty concentrating or remembering information
- Muscle aches, weakness or joint discomfort
- Heavy or irregular menstrual periods
These symptoms can also occur with other health conditions. A healthcare professional can determine whether thyroid dysfunction may be contributing to your symptoms.
When left untreated, hypothyroidism can contribute to complications such as elevated cholesterol, heart problems and fertility difficulties. Severe untreated hypothyroidism can rarely cause a life-threatening medical emergency.
How Is Hypothyroidism Treated?
Hypothyroidism is commonly treated with levothyroxine, a prescription medication that replaces the thyroid hormone your body is not producing in sufficient amounts. The goal of treatment is to restore appropriate hormone levels and relieve symptoms.
Your healthcare professional will determine the appropriate dosage based on factors such as your age, medical history and thyroid function test results. Blood tests are typically repeated about six to eight weeks after starting treatment or changing the dose to determine whether adjustments are needed.
Levothyroxine should be taken consistently according to your healthcare professional's instructions. Certain foods, medications and supplements, including calcium and iron, can interfere with how the medication is absorbed.
Many people with hypothyroidism require lifelong treatment. However, some cases, particularly those caused by temporary thyroid inflammation, may improve over time.
Healthy eating and regular physical activity support overall well-being, but they do not replace thyroid hormone treatment when it is needed.
What Is Hyperthyroidism?
Hyperthyroidism occurs when the thyroid gland produces more thyroid hormone than the body needs. Excess thyroid hormone can speed up metabolism and affect several bodily functions, including heart rate, digestion and temperature regulation.
The most common cause of hyperthyroidism is Graves' disease, an autoimmune condition that causes the thyroid to produce excessive amounts of hormone.
Other causes include overactive thyroid nodules, thyroiditis and excessive iodine intake. Some medications can also contribute to thyroid dysfunction.
Common Symptoms of Hyperthyroidism
Symptoms of an overactive thyroid can develop gradually or appear more suddenly. The severity of symptoms depends on factors such as age, hormone levels and underlying health conditions.
Common symptoms include:
- Unexplained weight loss, sometimes despite an increased appetite
- Rapid or irregular heartbeat
- Nervousness, anxiety or irritability
- Hand tremors or shakiness
- Increased sweating or sensitivity to heat
- Difficulty sleeping
- Frequent bowel movements
- Muscle weakness or fatigue
- Changes in menstrual periods
Some people with Graves' disease may also develop thyroid eye disease, which can cause eye irritation, bulging eyes or vision changes.
Untreated hyperthyroidism can increase the risk of complications such as irregular heart rhythms, heart problems and bone loss. Recognizing symptoms and receiving appropriate treatment can help reduce these risks.
How Is Hyperthyroidism Treated?
Treatment for hyperthyroidism depends on the underlying cause, severity of symptoms, age and overall health. Your healthcare professional may recommend medication, radioactive iodine therapy or surgery.
Antithyroid Medications
Antithyroid medications, such as methimazole, reduce the amount of thyroid hormone produced by the gland. These medications are commonly used to treat certain causes of hyperthyroidism, including Graves' disease.
Regular blood tests help monitor hormone levels and determine whether medication adjustments are needed. Antithyroid medications are not appropriate for every cause of excess thyroid hormone, such as thyroiditis.
Beta Blockers
Beta blockers may be prescribed to help manage symptoms such as a rapid heartbeat, tremors and nervousness while other treatments take effect.
Although these medications can provide symptom relief, they do not reduce thyroid hormone production or treat the underlying cause of hyperthyroidism.
Radioactive Iodine Therapy
Radioactive iodine treatment uses a controlled dose of radioactive iodine to reduce the activity of the thyroid gland. Over time, this lowers thyroid hormone production.
Some patients develop hypothyroidism following treatment and require thyroid hormone replacement medication. Radioactive iodine treatment is not used during pregnancy or breastfeeding.
Thyroid Surgery
In certain cases, surgery to remove part or all of the thyroid gland may be recommended. This may be considered for patients with large goiters, certain thyroid nodules or other circumstances where medication or radioactive iodine treatment is not appropriate.
Patients who have their entire thyroid removed will need lifelong thyroid hormone replacement medication.
Your healthcare professional can explain the benefits and risks of each treatment and help determine the most appropriate approach for your condition.
How Are Thyroid Disorders Diagnosed?
Thyroid disorders are typically diagnosed through a combination of medical history, physical examination and blood tests that measure thyroid hormone levels.
Common thyroid tests include:
- Thyroid-stimulating hormone (TSH): Often the first test used to evaluate thyroid function. High TSH levels may indicate an underactive thyroid, while low levels may suggest an overactive thyroid.
- Free T4: Measures the amount of unbound thyroxine available in the bloodstream and helps evaluate thyroid function.
- T3: May be used to evaluate certain cases of suspected hyperthyroidism.
- Thyroid antibody tests: Help identify autoimmune conditions such as Hashimoto's disease or Graves' disease.
Depending on your symptoms and test results, your healthcare professional may also recommend imaging tests, such as a thyroid ultrasound or radioactive iodine uptake test, to better understand the cause of thyroid dysfunction.
Not everyone needs routine thyroid screening. However, testing may be appropriate even without noticeable symptoms for people with certain risk factors, a history of thyroid disease or specific pregnancy-related considerations.
If additional evaluation or specialized treatment is needed, your healthcare professional may refer you to an endocrinologist, a doctor who specializes in hormone-related conditions. Broward Health's endocrinology specialists diagnose and treat thyroid disorders, including hypothyroidism, hyperthyroidism and Graves' disease.
When Should You See a Doctor for Thyroid Symptoms?
Because thyroid disorders can cause symptoms similar to other medical conditions, it is important to seek an evaluation rather than trying to diagnose yourself based on symptoms alone.
Consider speaking with a healthcare professional if you experience:
- Persistent fatigue or unexplained changes in energy
- Unexplained weight gain or weight loss
- Changes in heart rate, including a frequently rapid or irregular heartbeat
- Unusual sensitivity to hot or cold temperatures
- Ongoing constipation or changes in bowel habits
- Changes in mood, concentration or sleep patterns
- Swelling or a noticeable lump in the front of your neck
If you have a family history of thyroid disease, an autoimmune condition or are pregnant or planning a pregnancy, ask your healthcare professional whether thyroid testing or additional monitoring may be appropriate.
Seek immediate medical attention for serious symptoms such as chest pain, fainting, severe confusion or a rapid heartbeat accompanied by significant weakness or difficulty breathing.
Find Thyroid Care at Broward Health
Thyroid conditions can affect your energy, metabolism and overall well-being, but the right treatment can help you manage symptoms and maintain your quality of life. If you're experiencing signs of an underactive or overactive thyroid, speaking with a healthcare professional is an important first step.
At Broward Health, our endocrinology specialists provide personalized care for thyroid disorders, including hypothyroidism, hyperthyroidism and Graves' disease. Our team works with you to understand your symptoms, evaluate your thyroid function and develop a treatment plan based on your needs.
