Thyroid: Hypothyroidism and Hyperthyroidism Explained

The thyroid is a butterfly-shaped gland located at the base of the neck. It produces T3 and T4 hormones, which regulate the metabolism of almost all body cells.

Hypothyroidism (underactive thyroid)

Symptoms

• Persistent fatigue
• Weight gain despite normal eating
• Excessive sensitivity to cold
• Constipation
• Dry skin, brittle hair
• Intellectual slowdown, memory problems
• Depression

Most frequent cause

Hashimoto's thyroiditis: an autoimmune disease where the immune system attacks the thyroid.

Treatment

Levothyroxine (synthetic thyroid hormone) for life, with dose adjustment according to TSH.

Hyperthyroidism (overactive thyroid)

Symptoms

• Weight loss despite preserved appetite
• Palpitations, tachycardia
• Nervousness, irritability, tremors
• Heat intolerance, excessive sweating
• Diarrhea
• Insomnia

Most frequent cause

Graves' disease: an autoimmune disease stimulating the thyroid.

Treatments

• Antithyroid drugs (carbimazole, propylthiouracil)
• Radioactive iodine
• Surgery (thyroidectomy)

When to check your thyroid?

• Persistent unexplained fatigue
• Weight variation without lifestyle change
• Mood disorders resistant to treatment
• Family history of thyroid disease
• Postpartum (postpartum thyroiditis)

A simple TSH test is enough to screen for thyroid dysfunction. It is an inexpensive and very informative routine examination.