Hyperthyroidism

Key Features

Essentials of Diagnosis

• Sweating, weight loss or gain, anxiety, palpitations, loose stools, heat intolerance, menstrual irregularity

• Tachycardia; warm, moist skin; stare; tremor

• Graves disease

  • Most common cause of hyperthyroidism

  • Most patients have a palpable goiter (sometimes with bruit); ophthalmopathy

• Amiodarone: most common cause of thyrotoxic crisis ("thyroid storm")

• Suppressed TSH in primary hyperthyroidism; usually increased T₄, FT₄, T₃, FT₃

General Considerations

Graves disease

• Most common cause of thyrotoxicosis

• An autoimmune disorder, characterized by an increase in synthesis and release of thyroid hormones

• More common in women than in men (8:1)

• Onset usually between the ages of 20 and 40 years

• May be accompanied by infiltrative ophthalmopathy (Graves exophthalmos) and, less commonly, by infiltrative dermopathy (pretibial myxedema)

• Patients with Graves disease have an increased risk of other systemic autoimmune disorders, including

  • Sjögren syndrome

  • Celiac disease

  • Pernicious anemia

  • Addison disease

  • Alopecia areata

  • Vitiligo

  • Type 1 diabetes mellitus

  • Hypoparathyroidism

  • Myasthenia gravis

  • Cardiomyopathy

Toxic multinodular goiter and thyroid nodules

• Autonomous hyperfunctioning thyroid nodules that produce hyperthyroidism are known as toxic multinodular goiter (Plummer disease); a single hyperfunctioning nodule can also produce hyperthyroidism

• More prevalent among older adults and in iodine-deficient regions

• Toxic multinodular goiter and Graves disease may sometimes coexist in the same gland (Marine-Lenhart syndrome)

• Thyroid cancer is found in about 5% of patients with toxic multinodular goiter

Thyroiditis

• These conditions cause thyroid inflammation which may release stored hormone

• Autoimmune thyroiditis (Hashimoto, postpartum thyroiditis, painless sporadic subacute thyroiditis), painful subacute thyroiditis, infectious thyroiditis, and IgG₄-related thyroiditis are detailed in Thyroiditis

Amiodarone-induced hyperthyroidism

• The leading cause for thyrotoxic crisis ("thyroid storm")

• Causes thyrotoxicosis in about 3% of patients in the United States

• Induces thyrotoxicosis in about 20% of patients in Europe and iodine-deficient geographic areas

• Thyrotoxicosis can occur at any time during treatment and may even develop several months after treatment discontinuation

Clinical Findings

Symptoms and Signs

• Heat intolerance, sweating

• Palpitations

• Pruritus

• Frequent bowel movements

• Weight loss (or gain)

• Menstrual irregularities

• Nervousness, fine resting tremor

• Fatigue

• Muscle weakness, muscle cramps, hyperreflexia

• Thyroid in Graves disease

  • Diffusely enlarged thyroid

  • Frequently asymmetric

  • Often has a bruit

• Eye

  • Upper eyelid retraction

  • Stare and lid lag with downward gaze

  • Thyroid associated ophthalmopathy (exophthalmos) in 20–40% of patients with Graves disease

  • Diplopia may be due to coexistent myasthenia gravis

• Skin

  • Moist warm skin

  • Fine hair

  • Onycholysis

  • Dermopathy (myxedema) in 3% of patients with Graves disease

• Heart

  • Palpitations or angina pectoris

  • Arrhythmias

    • Sinus tachycardia

    • Premature atrial contractions

    • Atrial fibrillation or atrial tachycardia (can precipitate heart failure)

  • Thyrotoxic cardiomyopathy due to thyrotoxicosis

• Thyrotoxic crisis or ...