Hypothyroidism: Causes, Symptoms, Types & Tests

Hypothyroidism, also known as an underactive thyroid, occurs when the thyroid gland does not produce enough thyroid hormones to meet the body’s needs. These hormones play a critical role in regulating metabolism, energy levels, and many other body functions. When hormone levels drop, it can slow bodily processes, leading to a wide range of symptoms from fatigue and weight gain to mood changes and hair thinning. Though often gradual in onset, hypothyroidism can significantly affect health if left untreated.

What is Hypothyroidism?

Hypothyroidism is a disorder in which the thyroid gland, located at the base of the neck, becomes underactive and fails to produce enough triiodothyronine (T3) and thyroxine (T4) hormones. These hormones influence nearly every cell in the body, affecting metabolism, temperature regulation, heart rate, digestion, and muscle control. When the thyroid doesn’t produce enough hormones, the body’s metabolism slows down. While hypothyroidism is more common in women, particularly those over 60, it can affect people of any age, including infants.

Causes of Hypothyroidism

Several conditions and factors can cause hypothyroidism:

• Autoimmune disease (Hashimoto’s thyroiditis): The most common cause, where the immune system mistakenly attacks thyroid tissue.
• Thyroid surgery: Removing all or part of the thyroid can reduce hormone production.
• Radiation therapy: Especially treatments to the neck or head that damage the thyroid.
• Congenital disease: Some babies are born with a defective thyroid or no thyroid at all.
• Iodine deficiency: Rare in places where iodine is added to salt but still a global cause.
• Certain medications: Such as lithium, which can interfere with hormone production.
• Pituitary disorders: The pituitary gland may fail to produce enough thyroid-stimulating hormone (TSH) to prompt the thyroid to function.
• Pregnancy: Some women develop hypothyroidism during or after pregnancy.

Recognizing these causes helps in diagnosis and planning appropriate treatment.

Symptoms of Hypothyroidism

The signs of hypothyroidism often develop slowly and may initially be subtle, making them easy to overlook. Common symptoms include:

• Fatigue and sluggishness: Feeling tired despite adequate rest.
• Weight gain: Often modest but persistent, even without dietary changes.
• Increased sensitivity to cold: Feeling chilled in normal environments.
• Dry skin and hair: Skin may appear pale, rough, or flaky; hair may become brittle.
• Constipation: Due to slowed digestive processes.
• Muscle weakness or cramps: Especially in the legs and arms.
• Swelling in the face: Particularly around the eyes.
• Hoarseness or a deepened voice.
• Elevated blood cholesterol levels.
• Depression or mood swings.
• Memory problems and difficulty concentrating.
• Menstrual changes: Heavier or irregular periods in women.

Because symptoms can resemble other conditions, testing is important for diagnosis.

Types of Hypothyroidism

Hypothyroidism is typically classified based on its cause or underlying mechanism:

1. Primary Hypothyroidism:

• The most common type, resulting from a direct problem with the thyroid gland itself (e.g., autoimmune disease, iodine deficiency, thyroid surgery).

2. Secondary Hypothyroidism:

• Occurs when the pituitary gland fails to produce enough TSH, which stimulates the thyroid to release hormones.

3. Congenital Hypothyroidism:

• Present at birth, often due to thyroid development issues.

4. Subclinical Hypothyroidism:

• Characterized by elevated TSH levels but normal T4 and T3 levels, often without obvious symptoms.

Each type requires a tailored approach to diagnosis and treatment.

Tests Used to Detect Hypothyroidism

Diagnosis relies heavily on blood tests to measure thyroid hormone levels:

• TSH (Thyroid-Stimulating Hormone): Elevated levels typically indicate hypothyroidism.
• Free T4 (Thyroxine): Measures active thyroid hormone; low levels support diagnosis.
• T3 (Triiodothyronine): Sometimes measured to provide additional insight.
• Thyroid antibody tests: Detect autoimmune causes like Hashimoto’s thyroiditis.
• Ultrasound: Used if there is suspicion of nodules or structural problems.
• Radioactive iodine uptake test: Helps evaluate thyroid function in certain cases.

These tests help doctors assess severity and underlying causes, guiding treatment choices.

Conclusion

Hypothyroidism may develop quietly but can profoundly impact overall health if untreated. Early detection through awareness of symptoms and regular health check-ups is crucial, especially for those at higher risk, such as women over 60 or those with a family history of thyroid disease. Treatment typically involves daily hormone replacement therapy, which can restore hormone balance and relieve symptoms. Lifestyle measures, like eating a balanced diet rich in selenium and iodine (within recommended limits), managing stress, and staying active, can also help support thyroid health.

Frequently Asked Questions

What is hypothyroidism?

Hypothyroidism is a condition where the thyroid gland produces too little thyroid hormone, slowing down body functions.

What causes hypothyroidism?

Common causes include autoimmune disease (Hashimoto’s), thyroid surgery, radiation, certain medications, and iodine deficiency.

What are the symptoms of hypothyroidism?

Symptoms include fatigue, weight gain, dry skin, hair thinning, constipation, and sensitivity to cold.

How is hypothyroidism diagnosed?

Mainly through blood tests measuring TSH and thyroid hormone levels.

Can hypothyroidism be cured?

While it isn’t usually cured, it is very manageable with hormone replacement therapy.

Who is at higher risk for hypothyroidism?

Women, especially over 60, and people with a family history of thyroid disorders.

What foods help support thyroid health?

Balanced intake of iodine, selenium, and zinc can help, but supplements should only be taken under medical advice.

Is hypothyroidism common?

Yes, it is one of the most common endocrine disorders worldwide, particularly among women.