In France, the incidence of congenital hypothyroidism has increased significantly since the newborn screening program was introduced in 1978. The largest increase is seen in children with eutopic thyroid gland. More than one-third of children with eutopic gland have transient hypothyroidism. Clinical practice guidelines recommend to re-evaluate thyroid function in children with eutopic gland around the age of 3 years to determine whether hypothyroidism is transient or permanent. Up until today it is still difficult to determine early on whether hypothyroidism is transient or permanent in children with eutopic gland. Our aim is to identify one or more predictive factors for transient congenital hypothyroidism in children with eutopic gland or thyroid hemiagenesis.

Inclusion Criteria:

• Children with congenital hypothyroidism
• Eutopic thyroid gland or thyroid hemiagenesis
• Born between 1996 and 2017
• Treated at the Nancy Regional and University Hospital
• Follow-up of at least 3,5 years.

Exclusion Criteria:

• Polymalformative syndrome
• Thyroid dysgenesis except for thyroid hemiagenesis

Children with congenital hypothyroidism either detected by newborn screening or by a blood test done because of clinical suspicion of hypothyroidism, in Lorraine, between 1996 and 2017. All the patients with confirmed hypothyroidism underwent thyroid imaging. The children with eutopic gland and hemiagenesis are included in this study.