Underactive Thyroid (Hypothyroidism): Causes, Symptoms, and Treatment

What is an Underactive Thyroid?

An underactive thyroid, or hypothyroidism, occurs when the thyroid gland does not produce enough hormones. These hormones—thyroxine (T4) and triiodothyronine (T3)—are essential for regulating metabolism, energy levels, and overall body function. If left untreated, hypothyroidism can lead to serious complications, but with proper treatment, most people can live a healthy, normal life.

Symptoms of an Underactive Thyroid

The symptoms of hypothyroidism can be mild and develop gradually, making them easy to overlook. Common symptoms include:

• Fatigue and weakness

• Unexplained weight gain

• Depression or low mood

• Dry skin and brittle nails

• Hair thinning or hair loss

• Constipation

• Muscle aches and joint pain

• Cold sensitivity

• Slow heart rate

• Memory problems and brain fog

• Heavy or irregular periods (in women)

Severe cases can lead to heart complications, hoarse voice, or even hearing loss.

Causes of an Underactive Thyroid

The most common causes of hypothyroidism include:

• Autoimmune diseases: The most frequent cause is Hashimoto’s thyroiditis, an autoimmune disorder where the immune system attacks the thyroid gland.

• Iodine deficiency: Though rare in developed countries, insufficient iodine can impair thyroid function.

• Previous thyroid treatment: Radioactive iodine therapy or thyroid surgery for an overactive thyroid (hyperthyroidism) can lead to hypothyroidism.

• Medications: Drugs like lithium (for bipolar disorder) and amiodarone (for irregular heartbeats) may interfere with thyroid hormone production.

• Pregnancy: Some women develop postpartum thyroiditis, a temporary form of hypothyroidism after giving birth.

Hypothyroidism in Women and Pregnancy

Women are 5 to 10 times more likely than men to develop an underactive thyroid. It is especially common during and after menopause. Many women mistake hypothyroid symptoms for menopause-related changes, leading to misdiagnosis or delayed treatment.

During pregnancy, hypothyroidism can cause complications such as miscarriage, preterm birth, and developmental delays in babies. Women with a history of thyroid issues should have regular thyroid function tests during pregnancy.

How is Hypothyroidism Diagnosed?

A thyroid function test (TFT) is the standard way to diagnose an underactive thyroid. Blood tests measure:

• Thyroid-stimulating hormone (TSH): High levels suggest the thyroid is underactive.

• Thyroxine (T4) levels: Low T4 confirms hypothyroidism.

• Triiodothyronine (T3) levels: Less commonly checked but can provide additional insights.

Subclinical hypothyroidism refers to cases where TSH is high but T4 is still within the normal range, indicating a risk of developing hypothyroidism in the future.

Treatment for an Underactive Thyroid

The standard treatment for hypothyroidism is levothyroxine (synthetic T4 hormone), taken daily to replace the missing thyroid hormones. Treatment is typically lifelong, but it is effective in restoring normal thyroid function and improving symptoms.

• Starting on a low dose: Doctors begin with a low dose of levothyroxine and adjust based on blood tests.

• Monitoring hormone levels: Regular blood tests ensure the correct dosage and help prevent overmedication.

• Lifestyle changes: A balanced diet rich in iodine, selenium, and zinc can support thyroid health. Regular exercise and stress management are also beneficial.

When to See a Doctor

Book an appointment if you:

• Experience persistent symptoms of hypothyroidism.

• Have a family history of thyroid disease.

• Notice a lump or swelling in your neck.

• Are pregnant or planning pregnancy and have thyroid concerns.

Get Medical Advice from TravelDoctor EU

If you suspect you have hypothyroidism, speak to a GP at TravelDoctor EU for an online consultation. For a full list of conditions we treat, visit What We Treat.

For further reading, check out:

• WebMD – Thyroid Disorders

• Mayo Clinic – Hypothyroidism
  

FAQs on Hypothyroidism

1. Can an underactive thyroid be cured?
No, but it can be effectively managed with lifelong levothyroxine treatment.

2. How long does it take to feel better after starting treatment?
Most people notice an improvement in symptoms within a few weeks, but full recovery can take several months.

3. Can hypothyroidism cause weight gain?
Yes, due to a slower metabolism. However, proper treatment can help regulate weight.

4. What foods should I avoid with hypothyroidism?
Limit soy products, cruciferous vegetables (in large amounts), and processed foods high in sugar and salt.

5. How often should I have my thyroid levels checked?
At least once a year, or more frequently if symptoms change or medication adjustments are needed.

Conclusion

Hypothyroidism is a common but manageable condition. With early diagnosis and proper treatment, most people can lead a normal and healthy life. If you're experiencing symptoms, don’t ignore them—speak to a doctor today.

Book an online consultation at TravelDoctor EU for expert thyroid care!