What is the initial treatment for hyperthyroidism in primary care?

Initial Treatment for Hyperthyroidism in Primary Care

For symptomatic hyperthyroidism in primary care, immediately initiate beta-blocker therapy (propranolol or atenolol/metoprolol) to control symptoms while arranging urgent specialist referral for definitive treatment with antithyroid drugs, radioactive iodine, or surgery. 1, 2

Immediate Symptomatic Management

• Start beta-blockers as first-line symptomatic treatment for all patients with hyperthyroidism presenting with tachycardia, palpitations, tremor, or anxiety. 1
• Beta-blockers rapidly improve cardiac, neurological, and metabolic symptoms by blocking the peripheral effects of excess thyroid hormone, even before thyroid hormone levels normalize. 1
• Propranolol is preferred due to its additional effect of inhibiting peripheral conversion of T4 to T3, though atenolol or metoprolol are acceptable alternatives. 1
• For grade 1-2 symptomatic hyperthyroidism, interrupt immune checkpoint inhibitors if applicable, start beta-blocker therapy, and restart immunotherapy when asymptomatic. 1

Diagnostic Confirmation Before Treatment

• Confirm hyperthyroidism with low TSH and elevated free T4/T3 levels before initiating any treatment. 2, 3
• Obtain a radioactive iodine uptake scan to differentiate between Graves disease (diffuse uptake), toxic multinodular goiter (patchy uptake), toxic adenoma (single hot nodule), and thyroiditis (low uptake). 3, 4
• Check for thyrotropin receptor antibodies or assess for thyroid eye disease to diagnose Graves disease specifically. 4

Antithyroid Drug Initiation in Primary Care

• Methimazole is the preferred antithyroid drug for initial treatment due to its longer half-life, once-daily dosing, and lower risk of severe side effects compared to propylthiouracil. 3, 5
• Propylthiouracil should only be used in specific situations: first trimester of pregnancy, thyroid storm, or methimazole intolerance/allergy. 6, 3
• Antithyroid drugs can be initiated in primary care while awaiting specialist consultation, particularly if symptoms are severe or specialist appointment is delayed. 2

Critical Safety Warnings for Propylthiouracil

• Propylthiouracil carries a black box warning for severe hepatotoxicity, including liver failure requiring transplantation and death, particularly in children and pregnant women. 6
• Patients on propylthiouracil must be counseled to immediately report symptoms of liver dysfunction: anorexia, pruritus, jaundice, light-colored stools, dark urine, or right upper quadrant pain. 6
• Monitor for agranulocytosis (usually within first 3 months): instruct patients to immediately report fever, sore throat, or signs of infection. 6
• Propylthiouracil can cause life-threatening vasculitis affecting skin, kidneys, or lungs—patients should report new rash, hematuria, decreased urine output, dyspnea, or hemoptysis. 6

Urgent Specialist Referral Criteria

• All patients with overt hyperthyroidism require specialist referral for definitive treatment planning, though beta-blockers and sometimes antithyroid drugs may be initiated in primary care. 2
• Refer urgently for: newly diagnosed hyperthyroidism, thyroid nodules >1cm, painful nodules, compressive symptoms from goiter, or thyroid eye disease. 2
• Patients with cardiac complications (atrial fibrillation, heart failure) or elderly patients require immediate specialist involvement. 1

Definitive Treatment Options (Specialist-Directed)

• Radioactive iodine ablation is the most widely used definitive treatment in the United States, resolving hyperthyroidism in >90% of patients with Graves disease. 3, 4
• Radioactive iodine is the treatment of choice for toxic multinodular goiter. 7
• Antithyroid drugs (methimazole) for 12-18 months may induce long-term remission in Graves disease but will not cure toxic nodular goiter. 7, 3
• Thyroidectomy is reserved for: large obstructive goiters with compressive symptoms, radioiodine refusal, or failed medical management. 7, 4

Special Populations Requiring Modified Approach

• Pregnant women or those planning pregnancy within 4 months should avoid radioactive iodine; propylthiouracil is preferred in the first trimester, then switch to methimazole for second/third trimesters. 7, 3
• Elderly patients with underlying cardiac disease require careful beta-blocker titration and urgent specialist referral due to increased risk of cardiac decompensation. 1
• Patients on amiodarone require thyroid function monitoring every 6 months, as amiodarone-induced hyperthyroidism is common in elderly patients. 2

Common Pitfalls to Avoid

• Never overlook hyperthyroidism in elderly patients—maintain high index of suspicion as presentation may be atypical with predominant fatigue, weight loss, or new-onset atrial fibrillation. 2
• Do not use radioactive iodine in pregnancy, lactation, or within 4 months of planned conception. 7
• Avoid starting antithyroid drugs without confirming the diagnosis with thyroid function tests and determining the underlying cause. 2, 3
• Do not use propylthiouracil as first-line therapy except in first trimester pregnancy or thyroid storm due to severe hepatotoxicity risk. 6, 3
• Radioactive iodine may worsen Graves ophthalmopathy—consider corticosteroid cover to reduce this risk. 7