Endocrine Abstracts

Background: Thyroid imaging is recommended in the workup of children suspected with Congenital Hypothyroidism (CHT). Many centres in UK currently do not undertake scintigraphy routinely in CHT workup due to pitfalls such as unavailability, questionable benefit over ultrasound, result may not influence decision to treat or not, time constraints to complete scan within 5 days of starting treatment, etc.

Aim: Retrospective analysis of scintigraphy data in diagnostic work up of children with suspected CHT in a single tertiary centre over 17.5 year period.

Method: All children who had scintigraphy as part of diagnostic workup of CHT between January 2006 to June 2023 were analysed. Scintigraphy result were classed as eutopic (normal uptake), ectopic and dysplasia/aplasia. Data collection included sex, ethnicity, plasma free thyroxin (fT4), plasma Thyroid Stimulating Hormone (TSH), treatment commenced or not and the outcome (permanent or transient) at age of 2.5 years.

Results: 102/170 (60%) of suspected CHT referrals underwent scintigraphy were analysed. 65% were females and 51% were of White Caucasian ethnicity (39% South Asian). 58% had eutopic gland, 27% dysplasia/aplasia and 15% ectopic. Median fT4 was higher and median TSH lower in the eutopic group compared to the other two groups. 96/102 (94%) were commenced on treatment. All those not started treatment (n = 6) had eutopic scan (TSH range 11-34 miu/l). Status of CHT permanence at age of 2.5 years were analysed (n = 84/96). 66/84 (79 %) had permanent CHT vs 18/84 (21 %) were transient (off treatment). Among permanent group, 42 % had eutopia, 41 % aplasia/dysplasia and 17% ectopia vs 89% eutopia and 11% ectopia among transient group. Median fT4 was lower (8.8 pmol/l vs 13 pmol/l) and median TSH higher (82 miu/l vs 52.1 miu/l) among the permanent group.

Conclusion: Eutopia was the most frequent finding in our cohort which makes Dyshormonogenesis as most common cause of CHT. Although scintigraphy is helpful in predicting permanent CHT with ectopia and dysplasia/aplasia, it is unhelpful in eutopia which is more than half of the cases. Ultrasound rather than scintigraphy along with biochemical markers (TSH and fT4) can help provide etiological diagnosis and predict permanence.