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 27 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.
01 Oct 2015 - 03 Oct 2015