ESPE Abstracts

Background: Congenital hypothyroidism (CH) occurs in 1:3000–1:4000 newborns. The majority of newborns with CH are detected by routine screening programs and treatment is promptly initiated following confirmatory thyroid function testing. Although early imaging studies do not influence the treatment decision or management, they establish the underlying diagnosis and may distinguish between permanent and transient CH.

Objective: To assess the role of early thyroid imaging in predicting the course and management of CH.

Methods: A retrospective study of full-term healthy CH infants diagnosed between 2000 and 2012 and followed for at least 3 years in our institution. Patients were categorized into three groups based on their thyroid imaging and CH outcome: agenesis/ectopic, eutopic-permanent, and eutopic-transient.

Results: Of the 142 infants who underwent imaging studies (scan 116 and ultrasonography 26), agenesis/ectopic thyroid was found in 58 (41%), and eutopic thyroid in 84 (59%) including hypoplasia in 32 (22.5%) and normal-sized gland with increased or normal uptake in 52 (36.5%). Imaging findings were comparable in the eutopic-permanent and the eutopic-transient groups (P=0.55). At initial evaluation, TSH levels were higher and FT₄ levels lower in the agenesis/ectopic vs eutopic-permanent and eutopic-transient groups (71.5±11.2 mU/l vs 49.1±27.9 mU/l and 42.5±29.1 mU/l; 6.8±4.9 pmo/l vs 11.4±6.4 and 12.5±5.1 pmo/l, respectively, P<0.001 for both parameters). Since the 3rd month of follow-up thyroxin requirements were significantly higher in the agenesis/ectopic compared to the eutopic-permanent group (P<0.001); since the 6th month they were significantly higher in the eutopic-permanent compared to the eutopic-transient group (P<0.01). Predictive factors for permanent CH were initial TSH >63.5 (P<0.001) and thyroxine dose >1.4 μg/kg per day at age >6 months (P<0.01).

Conclusions: Transient and permanent CH are distinct in TSH levels at diagnosis and thyroxin requirements throughout follow-up. Early thyroid imaging does not distinguish between permanent and transient CH and can be postponed and preformed according to clinical judgment or needs.