An audit on thyroid scintigraphy scan requests in benign thyroid disease

Abstract

BACKGROUND: Thyroid scintigraphy has a useful role in the assessment of the thyrotoxic patient, particularly when thyrotoxicosis coexists with thyroid nodularity and when TSH- receptor antibody (TRAB) is negative. The aim of this audit was to assess the indication for thyroid scintigraphy in the assessment of patients locally, with reference to the European Thyroid Association (ETA) and National Institute for Health and Care Excellence (NICE) guidelines.

METHODS: All scintigraphy scans carried out in adult patients with benign thyroid disease at Mater Dei Hospital in Malta, between January 2019 to December 2021, were analysed. The indications for the investigation and the imaging results were assessed using the hospital’s electronic records, as were the thyroid function tests, TRAB levels, and thyroid ultrasound scans if available.

RESULTS: In 55.95% of thyrotoxic subjects, there was no valid indication for thyroid scintigraphy, according to the ETA and NICE guidelines. 37.96% of these patients inappropriately referred for scintigraphy did not have a TRAB level checked prior to the scan date whilst 20.37% had a positive TRAB and no known thyroid nodules. 10.18% of scans were inappropriately ordered in euthyroid patients with thyroid nodules or euthyroid hyperthyroxinaemia.

CONCLUSION: TRAB levels should be checked in new-onset thyrotoxicosis. Thyroid scintigraphy is useful in the differential diagnosis of the thyrotoxic patient when there are co-existing thyroid nodules, especially if TRAB is negative. It is not recommended in the thyrotoxic patient with a positive TRAB and no known thyroid nodules or in the assessment of euthyroid patients with thyroid nodules.