A patient presents with B/L proptosis, heat intolerance and palpitations; most unlikely diagnosis here would be -

Ans. is 'c' i.e., Riedel's Thyroiditis As already mentioned above, a patient with Reidel's thyroiditis may present with hypothyroidism, but never with hypehyroidism. But one should be aware that thyroid ophthalmopathy is seen mainly in Grave's disease and very rarely in any other cause of hypehyroidism. Also know Diff. between hypehyroidism and thyrotoxicosis Thyrotoxicosis is the state of thyroid hormone excess and hypehyroidism means excessive thyroid function. Both are not synonyms, however the major causes of thyrotoxicosis are hypehyroidism caused by Grave's disease, toxic multinodular goitre and toxic adenomas. Causes of Thyrotoxicosis Primary hypehyroidism Grave's disease Toxic multinodular goitre Toxic adenoma Functioning thyroid carcinoma metastasis Activating mutation of the TSH Receptor - Activating mutation of Gsa (McCune-Albright syndrome) Struma ovarii (thyroid tissue within ovarian tumor) Jod-Basedow phenomenon (or iodine-induced hypehyroidism) : thyrotoxicosis may occur in patients with multinodular goitre, after intake of large amounts of iodine, in the diet or in the form of radiographic contrast material or drugs, especially amiodarone. Thyrotoxicosis without hypehyroidism Subacute thyroiditis - Silent thyroiditis Hashimoto's thyroiditis - transient hypehyroidism is seen during the initial destructive phase Other causes of thyroid destruction : amiodarone, radiation, infarction of adenoma Thyrotoxicosis factitia : thyrotoxis due to ingestion of excessive amounts of exogenous thyroid hormone or thyriod tissue Secondary hypehyroidism TSH secreting pituitary adenoma Thyroid hormone resistance syndrome : occasional patients may have features of thyrotoxicosis. Chorionic gonadotropin-secreting tumors Gestational thyrotoxicosis.