Congenital Hypothyroidism with a Delayed Thyroid-Stimulating Hormone Elevation in Very Premature Infants: Incidence and Growth and Developmental Outcomes

Overall usefulness of newborn screening for congenital hypothyroidism by using free thyroxine measurement

“…In a series reported by Woo et al, 16% of patients with CH-T with delayed TSH elevation had a TSH level >50 µIU/mL [12]. This indicates that at least a small portion of these patients may have moderate to severe hypothyroidism.…”

“…NICU, and newborns from multiple births [4,[12][13][14][15][16]. In these situations, the diagnosis of CH-T may be overlooked due to the suppression of the TSH level as a result of various drugs, hypothalamo-pituitary immaturity, and other effects of serious illness [17,18].…”

“…Although hypothyroidism under these conditions may be self-limiting, it can lead to intellectual disabilities if it is not detected and treated [11]. In addition, FT4 measurement may enable the identification of newborns with CH-T with delayed TSH elevation-found mainly in premature and/or low birth weight (LBW) newborns-who may not be identified by a primary TSH strategy [2,4,[12][13][14].…”

Incidence and Risk Factor of Permanent Hypothyroidism in Preterm Infants

“…This result indicates that these two distinct thyroid dysfunctions including CH and persistent HT have a different clinical course. Previous reports also suggests the possibility that HTT might be caused by clinical conditions associated with the preterm birth rather than the abnormality of the thyroid gland itself and therefore infants with persistent HTT showed a higher incidence of transient hypothyroidism after re-evaluation [19][20][21].…”

Congenital Hypothyroidism due to Thyroid Dysgenesis: From Epidemiology to Molecular Mechanisms

“…On the contrary, it tends to be associated with prolonged gestation 29 and with a skewing of the birth weight distribution to the right 30 . Nevertheless, the New England CH Cooperative reported in 2003 that a 'delayed TSH rise' occurred more often in VLBW newborns and suggested that a second sample be systematically obtained; scintigraphic scans to determine the possible cause of this delayed-onset hyperthyrotropinemia were not performed 31 and a recent update on a subset of these VLBW newborns has shown that the problem was transient, with no evidence of benefit from treatment 32 . Other studies showed that lowering the TSH cutoff on the first blood sample increased the number of preterm infants labeled as having CH [33][34][35] .…”