What is the diagnosis and treatment for a patient with suppressed TSH, elevated free T3, and elevated free T4 levels?

Diagnosis: Overt Hyperthyroidism (T3 Toxicosis)

This patient has overt hyperthyroidism, specifically T3 toxicosis, characterized by suppressed TSH (0.00), elevated free T3 (5.5), and elevated free T4 (1.59), and should be treated with methimazole as first-line therapy unless contraindications exist. 1, 2

Diagnostic Confirmation

Your patient's laboratory values definitively establish overt hyperthyroidism:

• Suppressed TSH (<0.1 mIU/L) indicates excessive thyroid hormone production 3
• Elevated free T3 and free T4 confirm this is overt hyperthyroidism, not subclinical disease 2, 3
• The combination of suppressed TSH with elevated thyroid hormones distinguishes this from subclinical hyperthyroidism (which would have normal T3/T4) 3

Next diagnostic steps:

• Obtain thyroid stimulating immunoglobulins (TSI) or TSH receptor antibodies to diagnose Graves disease 2
• Consider radioactive iodine uptake scan if the etiology remains unclear after antibody testing 2, 3
• Examine for goiter, thyroid nodules, or ophthalmopathy on physical exam 2

Treatment Approach

First-Line Pharmacologic Therapy

Initiate methimazole as the primary antithyroid medication for this 69-year-old patient 1, 2:

• Starting dose: 15-30 mg daily (depending on severity of hyperthyroidism) 1
• Methimazole is preferred over propylthiouracil due to lower hepatotoxicity risk, particularly important in older adults 1
• The drug works by inhibiting thyroid hormone synthesis 2

Add beta-blocker therapy immediately to control symptoms:

• Atenolol or metoprolol to manage tachycardia, tremor, and anxiety 2
• Beta-blockers provide rapid symptomatic relief while awaiting thyroid hormone normalization 2

Monitoring Protocol

Initial monitoring (first 3 months):

• Check TSH, free T4, and free T3 every 4-6 weeks during dose titration 4, 1
• Obtain complete blood count (CBC) with differential at baseline and if fever or sore throat develops to detect agranulocytosis 1
• Monitor liver function tests (ALT, AST, bilirubin) at baseline and if symptoms of hepatotoxicity develop 1

Target thyroid function:

• TSH within reference range (0.5-4.5 mIU/L) 4
• Free T4 and free T3 normalized to reference ranges 4

Critical Safety Warnings for Methimazole

Agranulocytosis risk (potentially life-threatening):

• Instruct patient to immediately report fever, sore throat, or signs of infection 1
• Discontinue methimazole immediately if agranulocytosis develops 1
• This typically occurs in the first 3 months of therapy 1

Hepatotoxicity risk:

• Monitor for anorexia, pruritus, right upper quadrant pain 1
• Discontinue if transaminases exceed 3 times upper limit of normal 1

Vasculitis risk:

• Watch for new rash, hematuria, decreased urine output, dyspnea, or hemoptysis 1
• Discontinue methimazole if vasculitis suspected; may require corticosteroids or immunosuppression 1

Definitive Treatment Options

After achieving biochemical control with methimazole, discuss definitive therapy 2:

Radioactive iodine ablation:

• Most widely used treatment in the United States 2
• Preferred for Graves disease or toxic multinodular goiter 2
• Results in permanent hypothyroidism requiring lifelong levothyroxine 2

Surgical thyroidectomy:

• Consider if large goiter with compressive symptoms 2
• Option for patients who refuse radioactive iodine 2
• Also results in permanent hypothyroidism 2

Continued antithyroid medication:

• Long-term methimazole is an option but has higher relapse rates 2
• Requires indefinite monitoring for medication side effects 1

Special Considerations for This 69-Year-Old Patient

Cardiac risk assessment is critical:

• Hyperthyroidism increases risk for atrial fibrillation, especially in elderly patients 4
• Obtain baseline ECG to assess for arrhythmias 2
• Consider echocardiogram if cardiac symptoms present 2

Bone health concerns:

• Prolonged hyperthyroidism accelerates bone loss in postmenopausal women 4
• Ensure adequate calcium (1200 mg/day) and vitamin D (1000 units/day) intake 4
• Consider bone density testing once euthyroid 4

Common Pitfalls to Avoid

• Do not delay treatment while awaiting etiology determination; start methimazole and beta-blocker immediately 2
• Do not use levothyroxine in this patient—this would worsen hyperthyroidism 4
• Do not ignore cardiac symptoms—untreated hyperthyroidism can cause heart failure, especially in elderly patients 4, 2
• Do not assume subclinical disease—elevated T3 and T4 with suppressed TSH is overt hyperthyroidism requiring treatment 3
• Do not overlook medication side effects—agranulocytosis and hepatotoxicity can be life-threatening 1