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Hyperthyroidism

Background

Overview

Definition
Hyperthyroidism is a pathological syndrome in which tissue is exposed to excessive amounts of circulating thyroid hormone.
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Pathophysiology
Causes of hyperthyroidism include increased synthesis of thyroid hormones (e.g., Grave's disease), release of preformed thyroid hormones due to destruction of thyroid tissue (e.g., thyroiditis), and exogenous thyroid hormone intake.
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Epidemiology
In the US, the prevalence of hyperthyroidism is estimated at 13,000 per 100,000 population. In Europe, the prevalence of hyperthyroidism is estimated at 800 per 100,000 population.
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Disease course
Hyperthyroidism leads to a higher incidence of AF and atrial flutter, and, at least partly by that mechanism, a higher risk of cerebral arterial thrombosis. Hyperthyroidism additionally leads to increased bone turnover and a negative bone balance.
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Guidelines

Key sources

The following summarized guidelines for the evaluation and management of hyperthyroidism are prepared by our editorial team based on guidelines from the American College of Obstetricians and Gynecologists (ACOG 2020), the Endocrine Society (ES 2020), and the American Thyroid Association (ATA 2016).
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Diagnostic investigations

Initial evaluation
As per ATA 2016 guidelines:
Determine the etiology of thyrotoxicosis. If the diagnosis is not apparent based on the clinical presentation and initial biochemical evaluation, perform diagnostic testing including:
measurement of thyrotropin receptor antibodies
determination of the radioactive iodine uptake, or
measurement of thyroidal blood flow on ultrasound
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Obtain a 123I or 99mTc pertechnetate scan when the clinical presentation suggests a toxic adenoma or a toxic multinodular goiter.
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  • Thyroid antibodies

  • Lipid profile

Medical management

Antithyroid drugs, general principles: as per ATA 2016 guidelines, consider a baseline CBC, including WBC count with differential, and a liver profile including bilirubin and transaminases prior to initiating anti-thyroid drug therapy for Graves' disease.
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  • Antithyroid drugs (pregnant patients)

  • Beta-blockers

  • Potassium iodide

  • Antihistamine therapy

  • Management of Graves' disease

  • Management of toxic multinodular goiter

  • Management of subclinical hyperthyroidism

  • Management of thyroid nodules

Nonpharmacologic interventions

Smoking cessation: as per ATA 2016 guidelines, advise smoking cessation in patients with Graves' disease and refer them to a structured smoking cessation program. Identify patients exposed to secondhand smoke and advise of its negative impact, as both firsthand and secondhand smoking increase Graves' orbitopathy risk.
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Therapeutic procedures

Radioactive iodine ablation, Graves' disease: as per ATA 2016 guidelines, optimize the treatment of comorbidities prior to radioactive iodine therapy.
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  • Radioactive iodide ablation (toxic goiter and adenoma)

  • Radioactive iodine ablation (pediatric patients)

  • Ethanol and radiofrequency ablation

Perioperative care

Pre-RAI corticosteroid coverage: as per ATA 2016 guidelines, insufficient evidence to recommend for or against the use of prophylactic corticosteroids in smokers who receive radioactive iodine and have no evidence of Graves' ophthalmopathy.
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  • Pre-thyroidectomy care (Graves' disease)

  • Post-thyroidectomy care in Graves disease

  • Post-thyroidectomy care (toxic multinodular goiter)

Surgical interventions

Thyroidectomy for Graves' disease: as per ATA 2016 guidelines, perform near-total or total thyroidectomy as the procedure of choice if surgery is chosen as the primary therapy for Graves' disease.
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  • Thyroidectomy for toxic multinodular goiter

  • Thyroidectomy in pediatric patients

  • Thyroidectomy for pregnant patients

  • Thyroidectomy for amiodarone-induced thyrotoxicosis

Specific circumstances

Pregnant patients, testing
As per ACOG 2020 guidelines:
Obtain thyroid function testing in patients with a personal or family history of thyroid disease, T1DM, or clinical suspicion of thyroid disease.
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Do not obtain thyroid function testing in patients with hyperemesis gravidarum unless other signs of overt hyperthyroidism are evident.
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  • Pregnant patients (management)

  • Pregnant patients (monitoring)

  • Pediatric patients

  • Patients with iodine-induced thyrotoxicosis

  • Patients with postpartum thyroiditis

  • Patients with Graves' ophthalmopathy

  • Patients with amiodarone-induced thyrotoxicosis

  • Patients with thyrotoxicosis due to destructive thyroiditis

  • Patients with other causes of thyrotoxicosis

Patient education

Counseling for radioactive iodide ablation: as per ATA 2016 guidelines, provide written advice concerning radiation safety precautions following treatment when administering radioactive iodine, and select an alternative therapy if the precautions cannot be followed.
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Follow-up and surveillance

Monitoring of patients on antithyroid drugs: as per ATA 2016 guidelines, obtain a differential WBC count during febrile illness and at the onset of pharyngitis in all patients taking antithyroid medication to exclude agranulocytosis.
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