Hypothyroidism: Causes, Symptoms & Treatment

Hypothyroidism is a condition in which the thyroid gland does not produce enough thyroid hormones (T3 and T4) to meet the body's metabolic needs. The thyroid is a small butterfly-shaped gland in the neck that controls metabolism, heart rate, and body temperature. When thyroid hormone levels are insufficient, all metabolic processes slow down, leading to various symptoms.

This is one of the most common endocrine disorders, affecting millions of people worldwide. It is highly treatable with thyroid hormone replacement therapy.

The most common cause is Hashimoto's thyroiditis, an autoimmune condition where the immune system attacks thyroid tissue. Other causes include:

• Iodine deficiency
• Thyroid surgery or radiation
• Medications (lithium, amiodarone)
• Pituitary or hypothalamic disease
• Congenital thyroid problems

Risk factors include female gender, family history of thyroid disease, and age over 60.

Symptoms develop gradually and may include:

• Fatigue and weakness
• Weight gain
• Slowed heart rate
• Cold intolerance
• Dry skin and brittle hair
• Depression and mood changes
• Memory problems
• Muscle aches

Severe untreated hypothyroidism can progress to myxedema, a life-threatening condition.

Diagnosis involves blood tests measuring:

• TSH (thyroid-stimulating hormone)
• Free T4 (thyroxine)
• Thyroid antibodies to detect autoimmune disease

TSH is typically the first screening test, as it is the most sensitive indicator of thyroid function.

Treatment involves:

• Daily levothyroxine (synthetic T4) therapy
• Regular TSH monitoring to adjust dosage
• Stable absorption (take on empty stomach)
• Annual or biennial thyroid function tests
• Adequate iodine intake

Most patients achieve normal metabolism and symptom resolution with proper thyroid hormone replacement.

Primary prevention is not possible for most causes. Adequate dietary iodine intake helps prevent iodine-deficiency hypothyroidism. Avoiding excess iodine and certain medications when possible may reduce risk.

See your doctor if you experience persistent fatigue, weight gain, or cold intolerance. Regular screening may be recommended for those with family history or at higher risk. Annual follow-up during treatment is standard.