The FALSE Statement is E
Statement E is incorrect: hyperthyroidism CAN be caused by pharmacological agents. 1
Analysis of Each Statement
Statement A - TRUE
Hyperthyroidism is indeed characterized by suppressed TSH (<0.01 mU/L) with elevated T3 and T4 levels in overt disease 1. In milder cases, T4 may be normal with only T3 elevated (T3-toxicosis), but TSH remains undetectable 1.
Statement B - TRUE
Tachycardia, resting tremor, and sweating are classic hyperthyroid symptoms resulting from increased adrenergic stimulation and elevated metabolic rate 1. These symptoms are more pronounced in younger patients and those with larger goiters 1.
Statement C - TRUE
Atrial fibrillation is a well-recognized complication of hyperthyroidism, and hyperthyroidism may be diagnosed following the initial presentation with AF 1. Studies show hyperthyroidism is present in approximately 10% of new-onset atrial fibrillation cases 2, and thyroid dysfunction has a prevalence of up to 76% in AF patients 3. Guidelines recommend TSH measurement in all new-onset AF evaluations 4.
Statement D - TRUE
Graves' disease is characteristically associated with diffuse thyroid gland enlargement 1. This distinguishes it from toxic nodular goiter, which presents with nodularity rather than diffuse enlargement.
Statement E - FALSE (The Correct Answer)
This statement is definitively false. Multiple pharmacological agents cause hyperthyroidism:
- Amiodarone: Causes thyrotoxicosis in 5-10% of treated patients 1
- Iodine: Can trigger iodine-induced hyperthyroidism, especially in patients with underlying thyroid autonomy 1
- Lithium: Associated with painless thyroiditis and hyperthyroidism 1
- Cytokines (e.g., interferon-alpha): Cause cytokine-induced thyrotoxicosis 1
The American Thyroid Association guidelines specifically include entire sections on managing drug-induced thyrotoxicosis, including detailed protocols for iodine-induced, cytokine-induced, and amiodarone-induced thyrotoxicosis 1.
Clinical Pitfall
A common error is assuming hyperthyroidism is always endogenous. Always obtain a medication history when evaluating thyrotoxicosis, particularly checking for amiodarone (cardiac patients), iodine-containing contrast or supplements, lithium (psychiatric patients), and interferon therapy 1.