What is the initial treatment for thyrotoxicosis (thyroid hormone imbalance)?

Initial Treatment for Thyrotoxicosis

Beta-blockers (such as atenolol or propranolol) are the initial treatment for thyrotoxicosis, providing symptomatic relief while the underlying cause is being determined and specific therapy is initiated. 1

Diagnostic Approach

• Check TSH and FT4 for case detection in symptomatic patients; T3 can be helpful in highly symptomatic patients with minimal FT4 elevations 1
• Consider TSH receptor antibody testing if there are clinical features and suspicion of Graves' disease (e.g., ophthalmopathy and T3 toxicosis) 1
• Low TSH with low FT4 suggests central hypothyroidism - evaluate for hypophysitis 1
• Monitor thyroid function every 2-3 weeks after diagnosis to detect transition to hypothyroidism, which is the most common outcome for transient subacute thyroiditis 1

Treatment Algorithm Based on Severity

Grade 1: Asymptomatic or Mild Symptoms

• Continue immune checkpoint inhibitors (if applicable) 1
• Beta-blocker (atenolol or propranolol) for symptomatic relief 1
• Close monitoring of thyroid function every 2-3 weeks 1
• For persistent thyrotoxicosis (>6 weeks), consider endocrine consultation for additional workup 1

Grade 2: Moderate Symptoms (able to perform ADLs)

• Consider holding immune checkpoint inhibitors until symptoms return to baseline 1
• Consider endocrine consultation 1
• Beta-blocker (atenolol or propranolol) for symptomatic relief 1
• Hydration and supportive care 1
• For persistent thyrotoxicosis (>6 weeks), refer to endocrinology for additional workup and possible medical thyroid suppression 1

Grade 3-4: Severe Symptoms (unable to perform ADLs)

• Hold immune checkpoint inhibitors until symptoms resolve to baseline with appropriate therapy 1
• Mandatory endocrine consultation for all patients 1
• Beta-blocker (atenolol or propranolol) 1
• Hydration and supportive care 1
• Consider hospitalization in severe cases 1
• Inpatient endocrine consultation can guide additional medical therapies including:
  • Steroids
  • Saturated solution of potassium iodide (SSKI)
  • Thionamides (methimazole or propylthiouracil)
  • Possible surgery in extreme cases 1

Specific Treatment Based on Etiology

Thyroiditis (Most Common)

• Self-limited process that typically resolves in weeks with supportive care 1
• Initial hyperthyroidism generally resolves to either primary hypothyroidism or occasionally to normal thyroid function 1
• Conservative management during the thyrotoxic phase is sufficient 1
• Non-selective beta blockers, preferably with alpha receptor-blocking capacity, for symptomatic patients 1

Graves' Disease

• Treatment options include antithyroid drugs, radioactive iodine, or surgery 2, 3
• First-line treatment is typically a 12-18 month course of antithyroid drugs 2
• Physical examination findings of ophthalmopathy or thyroid bruit are diagnostic of Graves' disease and should prompt early endocrine referral 1

Toxic Nodular Goiter

• Radioactive iodine or surgery are preferred for toxic nodules or goitres 2

Medication Information

Antithyroid Drugs

• Methimazole: Inhibits the synthesis of thyroid hormones but does not inactivate existing thyroxine and tri-iodothyronine 4
• Propylthiouracil: Inhibits both the synthesis of thyroid hormones and the conversion of T4 to T3 in peripheral tissues, making it potentially more effective for thyroid storm 5, 6

Important Considerations and Pitfalls

• Thyroiditis is the most frequent cause of thyrotoxicosis and is seen more commonly with anti-PD1/PD-L1 drugs than with anti-CTLA-4 agents 1
• In asymptomatic patients with FT4 that remains in the reference range, it is an option to monitor before treating to determine if there is recovery to normal within 3-4 weeks 1
• Development of a low TSH on therapy suggests overtreatment or recovery of thyroid function; dose should be reduced or discontinued with close follow-up 1
• If there is uncertainty about whether primary or central hypothyroidism is present during severe thyrotoxicosis, hydrocortisone should be given before thyroid hormone is initiated 1
• Recent evidence suggests no significant differences in mortality or adverse events between propylthiouracil and methimazole for treatment of thyroid storm, challenging current guidelines that recommend propylthiouracil over methimazole 6