A patient takes levothyroxine. Which of the following is a recognised adverse effect of EXCESSIVE dosing?

Correct answer: B. Tachycardia, palpitations and heat intolerance

• A. Bradycardia and cold intolerance are features of UNDER-treatment (persisting hypothyroidism), not of levothyroxine excess.
• B. CORRECT. Over-replacement with levothyroxine produces iatrogenic THYROTOXICOSIS: tachycardia, palpitations, atrial fibrillation, tremor, anxiety, heat intolerance, weight loss, insomnia and — with long-term over-treatment — reduced bone mineral density. In the dental setting the tachycardia and arrhythmia risk is the concern, and epinephrine should be used cautiously in a patient who appears clinically thyrotoxic.
• C. Macroglossia is a feature of untreated HYPOthyroidism (myxoedema) and of congenital hypothyroidism.
• D. ⚑ EXOPHTHALMOS is NOT caused by levothyroxine. It is a feature of GRAVES DISEASE specifically, produced by autoimmune infiltration of the retro-orbital tissues by fibroblasts and glycosaminoglycans. It is driven by the TSH-receptor antibody, not by thyroid hormone levels, and it does not occur with hormone replacement.

Note: ⚑ CONTESTED SOURCE KEY. The recall keyed 'exophthalmos' for this item. That is incorrect: exophthalmos is Graves-specific orbitopathy and is not an adverse effect of levothyroxine. Worth flagging to the group — if the examination truly offered exophthalmos as the only thyroid-related option, the item itself was flawed.