OVERVIEW
Thyroid disease is an umbrella term for conditions that affect how your thyroid functions. Hypothyroidism and hyperthyroidism are the two main types of thyroid disease. But they each have multiple possible causes. Thyroid diseases are treatable — usually with medication.
What is Thyroid Disease?
Thyroid disease is a general term for a medical condition that keeps your thyroid from making the right amount of hormones. It can affect people of all ages.
Your thyroid is a small, butterfly-shaped gland located at the front of your neck under your skin. It’s a part of your endocrine system and controls many of your body’s important functions by producing and releasing thyroid hormones, like thyroxine (T4) and triiodothyronine (T3).
Your thyroid’s main job is to control the speed of your metabolism (metabolic rate). This is the process of how your body transforms the food you consume into energy. All the cells in your body need energy to function. When your thyroid isn’t working properly, it can impact your entire body.
Types of thyroid disease
The two main types of thyroid disease are hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid), each with specific conditions that can cause them:
Conditions Causing Hypothyroidism:
- Hashimoto’s Disease: A chronic autoimmune disorder and the most common cause of hypothyroidism in iodine-sufficient areas.
- Iodine Deficiency: A lack of iodine in the diet can lead to hypothyroidism, commonly causing goiter in regions without iodized salt.
- Congenital Hypothyroidism: A condition present at birth where babies may have an absent or underactive thyroid, affecting about 1 in 2,000 to 4,000 births.
Conditions Causing Hyperthyroidism:
- Graves’ Disease: A chronic autoimmune condition and the most common cause of hyperthyroidism.
- Thyroid Nodules: Abnormal lumps on the thyroid that can be hyperfunctioning, leading to excessive hormone production.
- Excessive Iodine: High iodine levels from medications or dietary sources can cause the thyroid to produce too many hormones.
Conditions Affecting Both:
- Thyroiditis: Inflammation of the thyroid that can cause temporary hyperthyroidism, followed by hypothyroidism.
- Postpartum Thyroiditis: Occurs in some individuals after childbirth, initially causing hyperthyroidism, followed by hypothyroidism, usually temporarily.
How common is thyroid disease?
Thyroid disease is very common. About 20 million people in the United States have some type of thyroid condition.
Hypothyroidism (Underactive Thyroid)
Symptoms:
- Fatigue and weakness
- Weight gain
- Cold intolerance
- Dry skin and hair loss
- Constipation
- Depression
- Muscle cramps
- Slowed heart rate
Causes:
- Hashimoto’s Disease: An autoimmune disorder where the immune system attacks the thyroid gland, leading to hormone deficiency.
- Iodine Deficiency: Insufficient iodine intake can hinder thyroid hormone production, especially in regions without iodized salt.
- Congenital Hypothyroidism: A condition present at birth where the thyroid is absent or underactive.
- Thyroid Surgery or Radiation: Treatments for other thyroid conditions can damage the gland.
- Medications: Some drugs, such as lithium, can affect thyroid hormone production.
Hyperthyroidism (Overactive Thyroid)
Symptoms:
- Unexplained weight loss
- Increased appetite
- Rapid heartbeat (tachycardia)
- Anxiety and irritability
- Heat intolerance
- Sweating
- Tremors (shaking hands)
- Difficulty sleeping
Causes:
- Graves’ Disease: An autoimmune disorder that stimulates the thyroid to produce excessive hormones.
- Thyroid Nodules: Hyperfunctioning nodules can secrete extra thyroid hormones.
- Excessive Iodine: High levels of iodine from supplements or certain medications (like amiodarone) can cause the thyroid to overproduce hormones.
- Thyroiditis: Inflammation of the thyroid can lead to temporary hormone release and hyperthyroidism.
What are the Risk Factors for Thyroid Disease?
You may be at a higher risk of developing a thyroid condition if you:
- Are assigned female at birth (AFAB). People AFAB are five to eight times more likely to have a thyroid condition than people assigned male at birth (AMAB).
- Have a family history of thyroid disease.
- Have Turner syndrome.
- Take a medication that’s high in iodine.
- Live in a country or area that doesn’t have iodized table salt, which can lead to iodine deficiency.
- Are older than 60, especially if you’re AFAB.
- Have received radiation therapy to your head and/or neck.
Having an autoimmune disease also increases your risk, especially if you have:
- Pernicious anemia.
- Type 1 diabetes.
- Celiac disease.
- Addison’s disease (primary adrenal insufficiency).
- Lupus.
- Rheumatoid arthritis.
- Sjögren’s syndrome.