Predictive value of technetium-99m sodium pertechnetate thyroid scintigraphy in determining the permanence of congenital hypothyroidism.

Objectives: We aim to investigate the predictive value of [^99mTc] pertechnetate thyroid scintigraphy in determining the permanence of congenital hypothyroidism (CH).

Material and methods: A retrospective analysis of [^99mTc] pertechnetate thyroid scans performed for evaluation of CH at the Nuclear Medicine Unit of a hospital in Hong Kong between January 1, 2008, and December 31, 2018, was conducted. Scintigraphic findings and parameters at diagnosis, including thyroid stimulating hormone (TSH), free thyroxine (fT4), gender, and gestational age, were reviewed. The need for lifelong thyroxine replacement therapy was reviewed.

Results: The study included 85 subjects, with 74 (87.1%) presenting with eutopic thyroid and 11 (12.9%) showing thyroid dysgenesis. Patients with scintigraphic evidence of thyroid dysgenesis required permanent thyroid hormone replacement therapy. Among the patients with eutopic thyroid, a higher TSH level was associated with the need for lifelong thyroid hormone replacement therapy (cutoff TSH value 18.72 mIU/L, sensitivity 77.3% and specificity 53.8%). Gender, gestational age, and fT4 did not show significant differences between the transient and permanent CH groups in patients with eutopic thyroid.

Conclusion: Scintigraphic findings of thyroid dysgenesis indicate a high prevalence of permanent CH. In patients with eutopic thyroid, higher TSH levels predict the requirement for lifelong thyroid hormone replacement therapy. These results provide insights into the prediction of CH and aid in individualized treatment decisions for patients with CH.