Thyroid Case 3 Answers

1) What pattern of thyroid uptake is shown?

There is no discernible uptake by the thyroid gland. Salivary gland and salivary activity is all that can be seen in the head and neck.

2) What is the likely implication of this in a thyrotoxic patient?

In a thyrotoxic patient reduced or absent thyroid uptake is usually indicative of a thyroiditis. The type of thyroiditis most commonly causing thyrotoxicosis is subacute (DeQuervain’s) thyroiditis, a destructive post-viral thyroiditis typically occurring 2-3 weeks after an upper respiratory tract infection. Patients will often have a tender thyroid and/or fever. It is a self-limiting condition, though some patients will subsequently develop temporary hypothyroidism, and increased thyroid radionuclide uptake may be seen as a rebound phenomenon in the recovery phase.

3) What are the other causes of this pattern of thyroid uptake in patients with hyperthyroidism?

Other types of thyroiditis that may present with thyrotoxicosis include chronic lymphocytic (Hashimoto’s) thyroiditis (usually presents with hypothyroidism but 4% of patients will experience hyperthyroidism in the early stage), post-partum thyroiditis and amiodarone-induced thyroiditis. Two other possibilities to consider are an excess of exogenous thyroxine administration (thyrotoxicosis factitia) or excess ectopic endogenous thyroid hormone production (e.g. struma ovarii – a rare ovarian teratoma containing functioning thyroid tissue).

4) What is the implication of A?

This is the gastric fundus, apparently on the right side. Either the side markers are wrong (unlikely as this is an anterior view) or the stomach truly is on the right. In fact, this patient was known to have situs inversus, a condition where there is a mirror-image of the normal distribution of the viscera with respect to the midline. There is no association with thyroid disease.

Contributed by Ian Hagan

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