Endocrine Abstracts

Thyroid uptake scan is a widely used thyroid investigation that provides valuable information regarding the structure and function of the gland and helps in differentiating some of the common thyroid pathologies. We present a multicentre audit of thyroid uptake scans done for non-malignant thyroid pathologies and try to analyse the usefulness of this investigation in different situations.

Methods

This audit includes thyroid uptake scans from two centres (King’s Mill Hospital Sherwood Hospitals NHS Foundation Trust Nottinghamshire UK and Hospital Central de la Defensa Gómez Ulla Madrid Spain) done over two years (2018 and 2019). Medical and electronic records were examined to get the data on presenting thyroid functions, TSH receptor antibodies (TrAB), clinical neck examination, thyroid uptake scan results, final diagnosis and management.

Results

A total of 117 cases were analysed; 27 from UK and 90 from Spain. 113 of these patients were hyperthyroid. 26 patients had positive TrAB (TrABs not available in 7). Clinical examination data was available for 98 patients; 27 normal, 38 diffuse goitre, 21 single nodule, 12 multiple nodules. Final diagnosis was Graves’ disease in 27, thyroiditis in 11, toxic multinodular goitre in 30, toxic nodule in 19 and 10 patients had other diagnoses. 20 patients were found to have non nodular hyperthyroidism with negative TrABs. We also performed subgroup analyses to see whether thyroid uptake scans significantly altered diagnosis or management. Unsurprisingly, there was no significant benefit from the thyroid uptake scan in those with hypothyroidism (4) or secondary hyperthyroidism (2). In those with TrAB positive hyperthyroidism (Fig 1) and a non-nodular thyroid examination, thyroid uptake scan did not add any significant information to aid in diagnosis or management; merely confirming the diagnosis of Graves’ disease in all patients.

Fig 1: Sub group analysis of TrAB positive hyperthyroidism.

In those with TrAB negative hyperthyroidism (fig 2), thyroid uptake scan significantly altered the pre scan probable diagnosis but whether it changed the eventual management in all of these patients is not entirely clear.

Fig 2: Sub group analysis of TrAB negative hyperthyroidism.

Conclusion

Our results show that thyroid uptake scan can be useful in patients with TrAB negative hyperthyroidism and TrAB positive hyperthyroidism with a nodular thyroid on examination. Amiodarone induced thyrotoxicosis is also an accepted indication of thyroid uptake scan. Clinicians should evaluate each case on an individual basis to see if uptake scan will significantly alter the diagnosis or management before requesting.