Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormones, affecting metabolism, energy levels, and multiple body systems.
Common symptoms include fatigue, weight gain, cold sensitivity, and cognitive changes that often develop gradually. Diagnosis is confirmed through blood tests that measure thyroid-stimulating hormone and thyroid hormone levels. Understanding the causes, symptoms, and when to seek medical evaluation can help prevent complications and guide appropriate care.
Introduction to Hypothyroidism
Hypothyroidism, often called an underactive thyroid, occurs when the thyroid, a small butterfly-shaped gland at the front of the neck, does not produce enough thyroid hormones to meet the body’s needs.
Thyroid hormones (thyroxine (T4) and triiodothyronine (T3)) play a key role in regulating metabolism and how efficiently the body converts nutrients into energy. They also help regulate processes such as heart rate, digestion, body temperature, and brain function.
When thyroid hormone levels are too low, metabolic activity slows. This can cause weight gain, persistent fatigue, and a general sense that the body is not functioning at its usual pace.
While most common in women, particularly after menopause, hypothyroidism is one of the most common thyroid disorders and can affect anyone of any age.
In most cases, an underactive thyroid can be effectively managed once it is properly identified. However, when left untreated for long periods of time, low thyroid hormone levels can contribute to worsening symptoms and may affect multiple body systems.
Because symptoms often develop gradually and can mimic other conditions or even general aging, reduced thyroid function may go unrecognized until it is identified through blood testing during medical evaluation.
What Is the Difference Between Hypothyroidism and Hyperthyroidism?
Hypothyroidism and hyperthyroidism are both conditions that involve the thyroid gland. The fundamental difference lies in the level of thyroid hormone produced, which leads to opposite hormone imbalances and clinical effects.
- In hypothyroidism, the thyroid is underactive and does not produce enough hormones, which generally leads to a slowing of metabolic processes and symptoms such as weight gain, fatigue, and cold sensitivity.
- In hyperthyroidism, the thyroid is overactive and produces excess thyroid hormones. This typically speeds up metabolism and other body systems, resulting in symptoms such as weight loss, anxiety, heat intolerance, insomnia, a rapid heart rate, and sweating.
What Causes Hypothyroidism?
Hypothyroidism can develop for several reasons, all of which affect the thyroid’s ability to produce enough thyroid hormone or the body’s ability to regulate hormone production properly. Some causes involve direct damage to the thyroid gland, while others interfere with hormone signaling or immune regulation.
The Leading Cause of Hypothyroidism: Autoimmune Disease (Hashimoto’s Thyroiditis)
The most common cause of hypothyroidism is Hashimoto’s thyroiditis, an autoimmune condition in which the immune system gradually attacks the thyroid gland. Over time, this immune-driven damage reduces the gland’s ability to produce thyroid hormones. Because the process is slow and progressive, symptoms may take years to develop fully.
Other Causes of Hypothyroidism
Thyroid Surgery
Sometimes surgery to remove part or all of the thyroid gland is necessary to treat thyroid cancer, large nodules, or an enlarged thyroid. When thyroid tissue is removed, hormone production may decrease significantly or stop altogether.
Certain Medical Treatments
Some medical treatments can impair thyroid function. Radiation therapy to the head, neck, or upper chest can damage thyroid tissue and reduce hormone production. In addition, treatments used to manage hyperthyroidism, such as radioactive iodine, intentionally reduce thyroid activity and may result in hypothyroidism over time.
Thyroiditis (Inflammation of the Thyroid)
Inflammation of the thyroid gland can occur after a viral illness or following pregnancy, a condition known as postpartum thyroiditis. In many cases, thyroiditis causes a temporary release of stored thyroid hormones, followed by a period of reduced hormone production. Some individuals recover fully, while others develop permanent hypothyroidism.
Certain Medications
Some medications can interfere with thyroid hormone production or release. Common examples include lithium, which is used to treat certain psychiatric conditions, and amiodarone, a medication used for heart rhythm disorders. Certain cancer therapies may also affect thyroid function.
Hormonal Changes
Hormonal shifts can influence thyroid function, particularly during pregnancy and the postpartum period. Postpartum thyroid dysfunction may occur within the first year after childbirth and can lead to temporary or permanent hypothyroidism.
Pituitary Gland Disorders
In some cases, hypothyroidism is not caused by a problem within the thyroid itself. Disorders of the pituitary gland can reduce the release of thyroid-stimulating hormone, which signals the thyroid to produce hormones. When this occurs, the thyroid may be structurally normal but underactive due to inadequate stimulation.
Other Risk Factors for Developing Hypothyroidism
Beyond direct causes, several factors can increase the likelihood of developing hypothyroidism, including:
- Age: Risk increases with age, particularly after midlife.
- Gender: Hypothyroidism occurs more often in women than in men.
- Family history: Having a close relative with thyroid disease or Hashimoto’s Thyroiditis can raise your risk.
- Other autoimmune conditions: Conditions such as celiac disease, type 1 diabetes, or Sjögren’s syndrome may increase risk.
- Certain nutritional deficiencies: Low levels of magnesium, folate, calcium, iron, and vitamins A, D, and B12 are associated with impaired thyroid function and, in some cases, may contribute to thyroid dysfunction. Severe iodine deficiency can also lead to hypothyroidism, although this is uncommon in the United States due to widespread iodized salt intake.
Is Hypothyroidism Genetic?
Hypothyroidism itself is not directly inherited. However, autoimmune thyroid disease can run in families. This means a person may inherit a higher risk of developing conditions like Hashimoto’s thyroiditis, which can then lead to hypothyroidism.
In rare cases, inherited genetic defects affecting thyroid hormone production or thyroid-stimulating hormone signaling can cause hypothyroidism, most often identified in infancy or childhood.
What are the Symptoms of Hypothyroidism?
There are many signs that your thyroid isn’t working right. In hypothyroidism, the body’s metabolism slows, which can result in both physical and cognitive symptoms that usually develop gradually.
Early Warning Signs of Hypothyroidism You Shouldn’t Ignore
The first signs of hypothyroidism are often subtle and may be mistaken for stress, aging, or lifestyle-related changes. Initial symptoms vary from person to person, but often include:
- Fatigue and low energy despite adequate rest
- Unexplained weight gain
- Cold intolerance
- Subtle changes in mood, concentration, or memory
Early indicators of an underactive thyroid can also mimic other conditions, making them easy to dismiss.
Common Symptoms of an Underactive Thyroid
As thyroid hormone levels continue to decline, symptoms may become more noticeable and widespread, and commonly include:
- Worsening fatigue, low energy, and weakness
- Unexplained weight gain or difficulty losing weight
- A puffy face, hands, and/or feet (due to fluid retention)
- Increased sensitivity to cold
- Aches, tenderness, stiffness, and weakness in muscles and joints
- Constipation
- A slow heart rate
- Depression or mood changes
- Memory problems (“brain fog”)
- A hoarse voice
- Swelling in the neck caused by an enlargement of the thyroid gland (Goiter)
To learn more about whether or not the symptoms you are having might be a thyroid issue, take this quick thyroid symptoms self-assessment quiz.
Symptoms of Hypothyroidism in Women
In addition to the common signs of hypothyroidism, women may experience symptoms related to reproductive and hormonal health, including:
- Menstrual changes, such as heavier, prolonged, or irregular periods, missed periods (amenorrhea), or unusually painful periods (dysmenorrhea)
- Fertility challenges, including difficulty becoming pregnant or an increased risk of pregnancy loss
- Worsening premenstrual symptoms (PMS)
Because many of these symptoms can overlap with normal life stages such as perimenopause or menopause, hypothyroidism in women is often overlooked or misattributed to hormonal changes unrelated to the thyroid.
Are Women More Likely to Develop Hypothyroidism?
Yes. Hypothyroidism occurs more frequently in women than in men. This is partly because estrogen and thyroid hormones interact within the body, and women are more likely to develop autoimmune conditions such as Hashimoto’s thyroiditis, the leading cause of hypothyroidism.
Diagnosing Hypothyroidism
Hypothyroidism is diagnosed through a combination of symptom evaluation, medical history, physical examination, and blood testing.
Because symptoms often develop gradually and can overlap with other conditions, no single symptom alone is enough to confirm the diagnosis. Ultimately, the diagnosis of hypothyroidism is confirmed through blood tests that measure thyroid hormone levels and how the body is responding to them.
How Is Hypothyroidism Diagnosed Through Blood Tests?
Blood tests are the primary and most reliable way to diagnose hypothyroidism.
The test measures thyroid-stimulating hormone (TSH), produced by the pituitary gland and signaling the thyroid to produce thyroid hormones. When thyroid hormone levels are too low, the pituitary releases more TSH to stimulate the thyroid.
Doctors also measure thyroxine (T4), the primary thyroid hormone circulating in the blood. In hypothyroidism, T4 levels are often low. In most cases, elevated TSH combined with low T4 levels confirms the diagnosis.
Triiodothyronine (T3) levels are frequently included in a complete thyroid panel and can provide additional clinical context. However, T3 levels often remain within the normal range in early or moderate hypothyroidism and are not typically used alone to confirm the diagnosis.
Living With Hypothyroidism
You can live a normal, healthy, and long life with hypothyroidism if it is properly managed.
In most cases, living with hypothyroidism includes taking daily thyroid medication to replace hormones the thyroid can no longer produce and regular blood tests to ensure thyroid levels remain stable.
Healthy lifestyle choices, such as getting adequate sleep, stress management, and eating a nutritious diet, can also support thyroid health.
What Are the Best Foods to Eat for Thyroid Health?
There isn’t a thyroid diet that treats hypothyroidism. However, specific nutrients are essential for normal thyroid hormone production and function, including:
- Iodine: Required to make thyroid hormones, though excessive intake can be harmful.
- Selenium: Supports thyroid hormone metabolism.
- Zinc: Plays a role in hormone production and immune function.
- Omega-3 fatty acids: Support inflammatory balance and hormone health.
- Antioxidants: Help protect cells from oxidative stress
Because low levels of vitamins D, A, and B12, as well as magnesium, folate, calcium, and iron, may play a role in the development or worsening of hypothyroidism, it can also be helpful to include foods rich in these nutrients as part of a balanced diet. A diet lower in pro-inflammatory foods, added sugars, and ultra-processed foods may also be beneficial.
Nutritional needs vary based on individual health, underlying conditions, and iodine exposure. Dietary choices for thyroid health should be discussed with a nutritionist or your healthcare provider.
Can Hypothyroidism Be Cured or Only Managed?
In most cases, hypothyroidism is not curable and is considered a long-term condition, particularly when caused by autoimmune disease or permanent thyroid damage.
However, some forms of hypothyroidism, such as those related to thyroid inflammation or postpartum thyroid dysfunction, may be temporary, and thyroid function can return to normal over time.
Whether hypothyroidism is temporary or permanent depends on the underlying cause and should be determined through medical evaluation and thyroid blood testing.
When to See a Doctor for Thyroid Evaluation
You should consider seeing a doctor for hypothyroidism if you experience persistent symptoms such as unexplained weight gain, ongoing fatigue, cold sensitivity, constipation, cognitive changes, or menstrual irregularities.
A doctor will order thyroid blood tests. Based on the results, you may be referred to a specialist for further evaluation. In some cases, a surgical evaluation is recommended. In these situations, a consultation with a surgeon may be appropriate to determine next steps.
Thyroid Care and Surgical Referral in Middle Tennessee
Some patients undergoing thyroid evaluation may be referred for surgical consultation if testing or imaging identifies thyroid nodules, enlargement, or other structural abnormalities.
If you have been advised to seek a surgical opinion for a thyroid-related concern, contact The Surgical Clinic to schedule an appointment at one of our Middle Tennessee locations.