Diagnosis: Graves Disease
The most likely diagnosis is A - Graves disease, given the classic triad of hyperthyroid symptoms (sweating, palpitations), goiter with discomfort, and suppressed TSH indicating thyrotoxicosis 1.
Clinical Reasoning
Why Graves Disease is Most Likely
Graves disease is the most common cause of hyperthyroidism globally, affecting 2% of women and 0.5% of men, making it statistically the most probable diagnosis 1.
The clinical presentation is classic for Graves disease: sweating and palpitations are cardinal symptoms of thyrotoxicosis, while the enlarged neck (goiter) with discomfort suggests an actively enlarged, hyperfunctioning gland 1, 2.
Low TSH confirms autonomous thyroid hormone overproduction, which occurs in Graves disease due to thyrotropin-receptor antibodies that continuously stimulate the thyroid gland 1, 2.
Patients with Graves disease characteristically present with a diffusely enlarged thyroid gland on examination, consistent with the "enlarged neck" described 1.
Why Other Options Are Less Likely
Subacute Thyroiditis (Option B):
- While subacute thyroiditis can cause thyrotoxicosis with low TSH, it typically presents with painful thyroid tenderness rather than just discomfort 3, 4.
- The thyrotoxic phase of thyroiditis is usually self-limiting and transient, often followed by hypothyroidism within 1-2 months 4.
- Treatment for thyroiditis is primarily supportive care or beta-blockers, not definitive therapy, because it resolves spontaneously 1.
Hashimoto's Thyroiditis (Option C):
- Hashimoto's thyroiditis is an autoimmune disease leading to thyroid tissue destruction and hypothyroidism, not hyperthyroidism 5.
- While Hashimoto's can occasionally have a transient thyrotoxic phase early in the disease, it is not the typical presentation and would not be the "most likely" diagnosis 5.
- The hallmark of Hashimoto's is elevated TSH with low thyroid hormones, the opposite of what is presented 3.
Multinodular Toxic Goiter (Option D):
- Toxic multinodular goiter typically occurs in older patients and presents with symptoms of local compression (dysphagia, orthopnea, voice changes) rather than just discomfort 3, 1.
- The goiter in toxic multinodular disease is usually nodular and irregular rather than diffusely enlarged 3.
- This diagnosis would require thyroid ultrasound or scintigraphy showing multiple autonomous nodules to confirm 3, 1.
Diagnostic Confirmation
To confirm Graves disease, the following tests should be ordered:
Thyrotropin-receptor antibodies (TRAb) or thyroid-stimulating immunoglobulins (TSI) - positive in Graves disease 1, 5.
Free T4 and T3 levels - expected to be elevated in overt hyperthyroidism from Graves disease 1.
Thyroid scintigraphy - would show diffusely increased tracer uptake throughout an enlarged gland, confirming Graves disease 3, 5.
Thyroid ultrasound - would demonstrate a diffusely enlarged gland with increased vascularity, rather than discrete nodules 3.
Clinical Pitfalls to Avoid
Do not assume all hyperthyroidism with goiter is Graves disease - always confirm with antibody testing or scintigraphy, as toxic multinodular goiter and thyroiditis can present similarly 3, 1.
Do not delay treatment while awaiting confirmatory tests if the patient is severely symptomatic - initiate beta-blockers immediately for symptom control 1, 2.
Be aware that thyroid pain or tenderness strongly suggests thyroiditis rather than Graves disease - the presence of discomfort alone is not specific enough to differentiate 3, 4.