What is the recommended surveillance and treatment plan for a patient with hyperthyroidism, including those with Graves' disease and toxic multinodular goiter?

Hyperthyroidism Surveillance and Monitoring

Initial Monitoring After Diagnosis

For patients with hyperthyroidism from Graves' disease or toxic multinodular goiter, monitor thyroid function tests (TSH and Free T4) every 2-3 weeks initially to assess response to therapy, with follow-up visits scheduled every 2-3 weeks initially, then every 1-3 months once stable. 1

Specific Monitoring Parameters

• Measure TSH and Free T4 at each visit during the initial treatment phase 1
• Add Free T3 measurement if TSH remains suppressed but Free T4 normalizes, as some patients have isolated T3 toxicosis 2
• Check for cardiovascular manifestations including heart rate, blood pressure, and cardiac rhythm at every visit, as untreated hyperthyroidism causes cardiac arrhythmias, heart failure, and increased mortality 2

Disease-Specific Surveillance Protocols

Graves' Disease

• Monitor for ophthalmopathy development at each visit, as Graves' disease may present with stare or exophthalmos 2
• Measure TSH-receptor antibodies to assess disease activity and predict recurrence risk after antithyroid drug discontinuation 3
• Assess goiter size at each visit, as goiter size equivalent to or larger than WHO grade 2 increases recurrence risk 3

Toxic Multinodular Goiter

• Evaluate for compressive symptoms including dysphagia, orthopnea, or voice changes from local compression of neck structures 2
• Perform thyroid ultrasonography to monitor nodule size and characteristics 3
• Consider thyroid scintigraphy if nodule characteristics change or new nodules develop 2

Treatment-Specific Monitoring

Patients on Antithyroid Drugs (Methimazole)

• Check complete blood count before starting therapy and if fever or sore throat develops, as agranulocytosis is a serious adverse effect 4
• Monitor liver function tests periodically, as hepatotoxicity can occur 4
• Assess for recurrence risk factors including age younger than 40 years, FT4 concentrations 40 pmol/L or higher, TSH-binding inhibitory immunoglobulins higher than 6 U/L, and goiter size equivalent to or larger than WHO grade 2 3
• Plan for 12-18 month treatment course initially, with recognition that recurrence occurs in approximately 50% of patients after this duration 3

Post-Radioactive Iodine Treatment

• Monitor for development of hypothyroidism, which is the primary long-term sequela of radioactive iodine therapy 5
• Check thyroid function tests every 4-6 weeks initially after radioactive iodine, then every 3-6 months once stable 6
• Assess for worsening ophthalmopathy in Graves' disease patients, as radioactive iodine may cause deterioration 5

Post-Thyroidectomy

• Monitor for hypothyroidism immediately postoperatively and long-term 5
• Check calcium levels and assess for hypocalcemia symptoms in the immediate postoperative period 7
• Evaluate vocal cord function if voice changes occur 7

Long-Term Surveillance

Cardiovascular Monitoring

• Screen for atrial fibrillation at every visit, as hyperthyroidism causes cardiac arrhythmias 2
• Monitor blood pressure and heart rate to assess for hypertension and tachycardia 7
• Treat cardiovascular manifestations with beta blockers (propranolol or atenolol) for symptomatic relief of tachycardia, tremor, and anxiety 1

Bone Health Assessment

• Screen for osteoporosis in patients with prolonged hyperthyroidism, as untreated hyperthyroidism causes osteoporosis 2
• Consider bone density testing in postmenopausal women and men over 50 with history of hyperthyroidism 2

Red Flags Requiring Urgent Endocrinology Referral

• Symptoms persisting beyond 6 weeks despite adequate therapy 1
• Severe symptoms or complications including thyroid storm, severe ophthalmopathy, or cardiac complications 1, 7
• Pregnancy or breastfeeding, as special treatment considerations are required 6
• Development of agranulocytosis (fever, sore throat, severe infection) on antithyroid drugs 4

Common Pitfalls to Avoid

• Failing to monitor frequently enough during initial treatment phase—every 2-3 weeks is essential to prevent overtreatment or undertreatment 1
• Missing subclinical hyperthyroidism in high-risk patients over 65 years, who require treatment to prevent osteoporosis and cardiovascular disease 2
• Not recognizing thyroid storm, a rare but life-threatening complication requiring multidisciplinary treatment 7
• Inadequate cardiovascular monitoring, as cardiac manifestations require early treatment with beta blockers to prevent significant cardiovascular events 7