Hyperthyroidism: Causes, Symptoms and Treatment

Hyperthyroidism: Causes, Symptoms and Treatment

Hyperthyroidism occurs when the thyroid gland produces excessive amounts of thyroid hormones (T3 and T4). This condition accelerates the body's metabolism, leading to a range of symptoms that can significantly affect quality of life. While less common than hypothyroidism, hyperthyroidism requires prompt diagnosis and treatment to prevent serious complications.

What Is Hyperthyroidism?

The thyroid gland, located in the front of the neck, produces hormones that regulate metabolism, heart rate, body temperature, and energy levels. In hyperthyroidism, the gland becomes overactive, flooding the body with excess thyroid hormones. This creates a state of metabolic overdrive.

According to the American Thyroid Association, hyperthyroidism affects approximately 1 in 100 people, with women being 2 to 10 times more likely to develop it than men. The prevalence increases with age.

Causes of Hyperthyroidism

1. Graves' Disease (Most Common — 60-80% of cases)

Graves' disease is an autoimmune disorder where antibodies (TRAb) stimulate the thyroid to overproduce hormones. It often runs in families and is associated with other autoimmune conditions. A 2020 study in Thyroid found that genetic factors account for 79% of susceptibility to Graves' disease.

2. Toxic Nodular Goitre

One or more thyroid nodules become autonomously overactive, producing excess hormones independent of TSH stimulation. More common in older adults and in iodine-deficient regions.

3. Thyroiditis

Inflammation of the thyroid (often viral) causes stored hormones to leak into the bloodstream. This causes temporary hyperthyroidism lasting weeks to months, often followed by a hypothyroid phase.

4. Excess Iodine Intake

Excessive iodine from supplements, contrast dyes, or certain medications (amiodarone) can trigger hyperthyroidism in susceptible individuals.

5. Medication-Induced

Levothyroxine overdose, whether intentional or accidental, is a common cause of iatrogenic hyperthyroidism.

Symptoms of Hyperthyroidism

Symptoms reflect an overactive metabolism:

• Weight loss despite increased appetite
• Rapid heartbeat (tachycardia) — often 100+ beats per minute
• Anxiety, irritability, and mood swings
• Tremor — fine shaking of the hands
• Heat intolerance and excessive sweating
• Frequent bowel movements or diarrhea
• Fatigue and muscle weakness
• Insomnia
• Menstrual changes — lighter or less frequent periods
• Goitre — enlarged thyroid gland
• Eye problems (in Graves' disease) — bulging eyes, dryness, double vision

A 2019 study in The Journal of Clinical Endocrinology & Metabolism found that patients with untreated hyperthyroidism had a 2.5-fold increased risk of atrial fibrillation and a 1.5-fold increased risk of heart failure.

Diagnosis

Diagnosis involves:

• TSH: Low (often < 0.01 mIU/L)
• Free T4 and Free T3: Elevated
• TRAb antibodies: Positive in Graves' disease
• Thyroid scan: Shows uptake pattern (diffuse in Graves', focal in toxic nodules)
• Ultrasound: Assesses gland size and nodules

Treatment Options

1. Antithyroid Medications (Methimazole, Carbimazole, PTU)

These drugs block thyroid hormone production. Methimazole is first-line for most patients. Treatment typically lasts 12-18 months, with 40-50% achieving remission. A 2019 Cochrane review found no significant difference in remission rates between 12 and 18 months of treatment.

2. Radioactive Iodine (RAI) Therapy

RAI is taken orally and destroys overactive thyroid tissue. It is highly effective (80-90% cure rate) but often results in hypothyroidism requiring lifelong levothyroxine. Contraindicated in pregnancy and active Graves' eye disease.

3. Surgery (Thyroidectomy)

Reserved for large goitres, suspicious nodules, or patients who cannot take medications. Requires lifelong thyroid hormone replacement.

4. Beta-Blockers

Used for symptom control (rapid heartbeat, tremor, anxiety) while definitive treatment takes effect. They do not reduce thyroid hormone levels.

Complications of Untreated Hyperthyroidism

• Atrial fibrillation and heart failure
• Osteoporosis (bone loss from excess thyroid hormones)
• Thyroid storm (life-threatening crisis)
• Eye disease (Graves' ophthalmopathy)
• Pregnancy complications

Conclusion

Hyperthyroidism is a treatable condition with multiple effective options. Early diagnosis through TSH testing and appropriate treatment can prevent serious cardiovascular and skeletal complications. If you experience unexplained weight loss, rapid heartbeat, or anxiety, request a thyroid panel from your doctor.

References:

• American Thyroid Association. (2016). Guidelines for diagnosis and management of hyperthyroidism. Thyroid, 26(10), 1343-1421.
• Ross, D.S., et al. (2016). American Thyroid Association guidelines for diagnosis and management of hyperthyroidism. Thyroid, 26(10), 1343-1421.
• Bahn, R.S., et al. (2011). Hyperthyroidism and other causes of thyrotoxicosis. The Lancet, 377(9765), 555-565.
• Tunbridge, W.M., et al. (1977). The spectrum of thyroid disease in a community. Clinical Endocrinology, 7(6), 481-493.
• Abraham-Nordling, M., et al. (2011). Incidence of hyperthyroidism in Sweden. European Journal of Endocrinology, 165(6), 899-905.