Clinical Features of Patients with Congenital Hypothyroidism Due to Ectopic Thyroid

ABSTRACT

OBJECTIVE: This study aimed to describe the clinical features of patients with congenital hypothyroidism due to ectopic thyroid including locations of ectopic thyroid, thyroid function, age of treatment, and starting dose of medication. METHODS: A total of 71 children with congenital hypothyroidism due to ectopic thyroid diagnosed by thyroid ultrasonography (USG) or 99mTc-petechnetate thyroid scan in the department of pediatrics, Soonchunhyang University Seoul Hospital from 1992 to 2015 were enrolled and analyzed retrospectively. RESULTS: Among 71 patients, 26 patients (36.6%) were male and 45 patients (63.4%) were female as the gender ratio was 11.73. The locations of ectopic thyroid confirmed by USG or scan were found to be sublingual in 52 patients (73.2%), lingual in 17 patients (23.9%), prelaryngeal in 1 patient (1.4%), and combined in 1 patient (1.4%), respectively. The average value of serum thyroid stimulating hormone was 267.5 µIU/mL and free thyroxin was 0.63 ng/dL. The average value of thyroglobulin (TG) was 217.6 ng/mL. Fifty two patients (73.2%) started treatment within the 1 month of age and 19 patients (26.8%) started after the 1 month of age. The average of the medication starting dose was 12.2 µg/kg/day. There was no significant difference on TG value and starting medication dose. CONCLUSION: As the previous literatures, the presence of ectopic thyroid was more common in female than male. It was coincident with this study. It is generally accepted that lingual ectopic thyroid is most common ectopic location, but in this study, proportion of sublingual thyroid was most common.