ESPE Abstracts

Background: Congenital hypothyroidism (CH) comprises a heterogeneous group of disorders that includes diseases of the hypothalamo-hypophyseal system. The latter are missed on TSH based screening programs leading to increased morbidity and mortality. Additional T₄ determinations, allows an early detection of CH of central origin (CH-C).

Objective and hypotheses: To report the findings of a neonatal screening program based on determination of TSH and T₄ for early detection of CH-C.

Method: Between June 2014 to March 2015, 29 100 term newborns aged 2–7 days, were included. Screening strategy included TSH (IFMA Delfia), cutoff 10 mU/l and T₄ (FIA Delfia), cutoff 4.5 μg/dl serum, (−2.3 SDS) in filter paper blood samples. Infants suspicious of CH-C were referred to a paediatric endocrinologist. They underwent a thorough clinical assessment and determination of serum TSH, T₄, fT₄, T₃, thyroglobulin, antithyroid-antibodies, cortisol, GH, prolactin, LH, FSH, testosterone (boys), glycaemia and electrolytes. Serum TBG was performed in patients likely to have hypoTBGemia. Brain imaging was performed.

Results: Nineteen patients with low T₄ and TSH <10 mU/l were recalled (mean age 3.1 days). Of these, ten infants had transient hypothyroxinemia (nine non-thyroidal illnesses; one healthy). Five boys had hypoTBGemia (mean T₄ 2.6 μg/dL; TBG <3.5 μg/dl). Three had permanent CH-C (mean T₄ 3.9 μg/dl) due to a hypothalamo-hypophyseal disorder (1:9700). These patients remained hospitalized due to morbid conditions (one hypernatremia; two hypoglycaemias). All of them had multiple pituitary hormone deficiency. MRI showed midline defects. One additional patient with poor weight progression and cholestasis normalized T₄ but remained with isolated ACTH deficiency. Hormonal replacement was instituted at a mean age of 12.2 days.

Conclusion: Inclusion of T₄ determination allowed us to identify CH-C as a prevalent condition, to detect T₄ transport defects and transient hypotiroxinemia due to systemic diseases. In CH-C infants additional detection of other life-threatening hormone deficits, facilitated a timely treatment preventing mayor morbidity.

Funding: This work was supported by the Fundación de Endocrinología Infantil a non profit organization.