Gestational age, not transient hyperthyrotropinemia impacts brain white matter diffusion tensor imaging in premature infants

Abstract

Abstract. Transient hypothyroidism is common in premature infants and increases the risk of adverse neurodevelopmental outcomes. Thyroid hormone (TH) is involved in oligodendrocyte development and myelination, however, whether transient hypothyroidism is associated with oligodendrocyte dysplasia and abnormal myelination is unclear. The aim of the present study was to investigate correlations among TH levels, neurodevelopmental outcomes and white matter (WM) microstructure in premature infants. The authors designed a cohort study recruiting 81 premature infants (age, 23-35 weeks). A total of 17 were born with a gestational age (GA) <30 weeks (early preterm group) and 64 of them were born with a GA ≥30 weeks (late preterm group). For outcome measurement, thyroid stimulating hormone (TSH) levels at 0, 18, and 24 h of admission were measured. Neurodevelopmental outcomes were assessed using Bayley III test. Diffusion tensor imaging was used to explore the characterization of WM microstructure. The data demonstrated that GA, however not TSH level was associated with neurodevelopmental outcomes in the following 2 years. Fractional anisotrophy (FA) increased with TSH0 levels over anterior limb of internal capsule, while axial diffusivity decreased with TSH0 levels over splenium of corpus callosum (CC). The late preterm group had more intact WM integrity over the internal and external capsule (EC) in FA compared with the early preterm group. Infants with motor dysfunction had significantly increased mean diffusivity (MD) values at regions of interest in the genu and splenium of CC.The results of the present study demonstrated that GA, however not transient hypothyroidism influenced neurodevelopmental outcomes in the premature infants. FA increased with age in a regionally-specific manner over regions of the internal capsule and EC. MD may act as a potential predictor for motor function in premature babies.

Incidence and severity of transient hypothyroxinaemia of prematurity associated with survival without composite morbidities in extremely low birth weight infants

“…Therefore, despite its transient nature and the epiphenomenon of severe illness, hypothyroxinaemia in ELBWIs could be a risk factor by itself for both acute mortality and morbidities 10 and later neurodevelopmental deficits in ELBWIs 24–26 . However, a recent study reported that GA, but not THOP, played a key role in neuromotor dysfunction in preterm babies 27 . Moreover, thyroid hormone treatment did not attenuate the severity of RDS 28,29 , reduce mortality up to the point of discharge 29 , or improve long-term neurodevelopmental outcome 28,29 .…”