Endocrine Abstracts

Introduction: With a prevalence of about one in 3000 newborns, congenital hypothyroidism (CH) is the leading cause of preventable mental retardation and growth failure. The objective of this work is to clarify the contribution of thyroid scintigraphy (TS) using technetium 99 m for the diagnosis of CH and this through the experience of the nuclear medicine department in Sahloul university Hospital.

Materials and methods: This is a retrospective study including 31 children diagnosed with CH, who were referred to the nuclear medicine department of Sahloul Hospital for a thyroid scintigraphy. The average age was 24 months (ranging from 1 month to 14 years). All patients benefited from an acquisition of images centered on the cervical region using the Pinhole collimator in anterior incidence, supplemented by a static acquisition centered on the abdomen 20 minutes after an intravenous injection of 37 to 185 MBq of technetium 99 m.

Results: The study included 18 girls and 13 boys with a sex ratio equal to 1.38. Four patients had Down’s syndrome and two patients had a congenital heart defect. Twelve patients (38.7%) had thyroid dysgenesis (6 agenesis and 6 ectopia). Nineteen patients (61.3%) had a thyroid in place with a different level of thyroid fixation (normal fixation (22.6%), high fixation (16.1%) and homogeneous and weak fixation (22.6%) suggesting a disorder of hormonogenesis.

Conclusion: Technetium-99 m thyroid scintigraphy helps in the identification of thyroid dysgenesis, which is the most common cause of CH. The use of iodine 123 with a perchlorate test is particularly preferred in the diagnosis of a hormonogenesis disorder. However, in the absence of iodine 123, as for the case in our country, technetium 99 m ST can be an acceptable alternative allowing an etiological orientation of CH.