The thyroid is a butterfly-shaped, hormone producing gland located in the throat. The hormones it produces help control nearly every major process that occurs in the body—including heart rate, blood pressure, metabolism, and body temperature. When the body produces too much or too little thyroid hormone, many different problems and symptoms can occur.
Key terms to know
When learning about any part of the body—or discussing symptoms or health concerns with a healthcare provider—it helps to understand the basic terminology.
Here are some key terms to help you understand conditions associated with the thyroid gland:
- Endocrine gland. This is the term for a hormone-producing gland. The thyroid gland is one example. Other examples are the adrenal glands and pituitary gland.
- Thyroid hormone. A hormone is a substance that circulates in the blood and helps control difference processes performed by cells and organs. The thyroid gland produces two hormones—thyroxine and triiodothyronine, which are collectively referred to as “thyroid hormone.”
- Hyperthyroidism. This is a condition that occurs when the thyroid gland produces too much thyroid hormone. It is also called “overactive thyroid.”
- Hypothyroidism. This is a condition that occurs when the body produces too little thyroid hormone. It is also called “underactive thyroid.”
Thyroid disorders are more common in females, more common in people over the age of 60, and more common among people who have a family history of thyroid disorders. However, thyroid problems also affect many people without these risk factors.
Hyperthyroidism and hypothyroidism can have different causes and cause different symptoms.
Symptoms of hyperthyroidism
The most common cause of an overactive thyroid is an autoimmune disease called Graves’ disease, where the body’s immune system causes damage to healthy tissues in the thyroid gland. Other causes include tumors on the thyroid gland, a tumor on the pituitary gland, inflammation of the thyroid gland, high consumption of iodine, and medications used to treat hypothyroidism.
Symptoms of hyperthyroidism include:
- Unintentional weight loss
- Rapid or irregular heartbeat
- Increased appetite
- Nervousness, anxiety, or irritability
- Trembling hands or fingers
- Heat intolerance or excessive sweating
- Increased sensitivity to light
- Difficulty sleeping or insomnia
- Muscle weakness or fatigue
- Changes in menstrual patterns in women
- Frequent bowel movements or diarrhea
- Changes in vision or eye irritation
Symptoms of hypothyroidism
An underactive thyroid can have many different causes, including:
- Health conditions that cause the thyroid to become inflamed
- Surgery or radiation therapy on the thyroid gland
- An autoimmune disease called Hashimoto's disease
- Certain medications used to treat cancer, diabetes, hypertension, and bipolar disorder
- Disorders that affect the pituitary gland
- Diets with too little iodine (not common in the United States)
Symptoms of hypothyroidism can vary from person to person and may include:
- Unintentional weight gain
- Fatigue or lethargy
- Depression or mood changes
- Dry skin or hair loss
- Feeling cold or intolerance to cold temperatures
- Constipation or decreased bowel movements
- Muscle weakness or cramps
- Joint pain or stiffness
- Irregular menstrual periods
- Memory problems or difficulty concentrating
- Hoarseness or a slow, raspy voice
- Puffy face or swollen eyelids
Thyroid disorders can cause a wide variety of symptoms and affect people in different ways. Also, many of the symptoms listed above can occur as the result of health conditions that are not related to the thyroid.
If you are experiencing symptoms or have noticed a change in how you feel, make an appointment with your healthcare provider. Left untreated, thyroid disorders can lead to complications that can have a long-term impact on a person’s health.
