The purpose of this study was first to clarify postnatal trends in sera T(4), free T(4) (FT(4)), T(4)-binding globulin, TSH, T(3), rT(3), and T(4) sulfate levels in cord and at 7, 14, and 28 d in groups of preterm infants at 23-27 wk (n = 101), 28-30 wk (n = 196), and 31-34 (n = 253) wk gestation, and second to compare these trends to those of term infants and also with cord sera levels of equivalent gestational ages (n = 812; 23-42 wk gestation). In all preterm groups, TSH and rT(3) decrease to below, T(4)-binding globulin increases to within, and T(3) and T(4) sulfate increase to above cord levels of equivalent gestational age. Term infants are hyperthyroxinemic relative to cord and nonpregnant adult levels of T(4). Postnatal T(4) increases are attenuated in 31- to 34-wk infants, absent in 28- to 30-wk infants (although levels are equivalent to gestational age), and crucially reversed in 23- to 27-wk infants. This immature group is hypothyroxinemic relative to other groups and to cord levels of equivalent gestational age. Compared with term infants, postnatal FT(4) increases are lower in 31- to 34-wk infants, attenuated in 28- to 30-wk infants, and absent in 23- to 27-wk infants. The 23- to 27-wk group is distinctive; they are hypothyroxinemic on T(4) levels, yet FT(4) levels are within the cord levels of equivalent gestational age.

Thyroid hormone is essential for fetal and neonatal development in particular of the brain, but little is known about regulation of fetal thyroid hormone levels throughout human gestation. The purpose of this study was to clarify developmental trends and interrelationships among T(4), free T(4) (FT4), thyroxine-binding globulin (TBG), TSH, T(3), rT(3), and T(4) sulfate (T4S) levels in cord and fetal blood sera (n = 639, 15-42 wk gestation) and correlate infant levels (23-42 wk gestation) to maternal values (n = 428, 16-45 yr) and those of nonpregnant women (n = 233, 16-46 yr). In cord and fetal serum, T(4), T(3), and TBG levels increase with gestation until term; TSH, FT4, T4S, and rT(3) levels increase and peak in the late second/early third trimester and then decline to term; T(4)/TBG ratios increase until late second trimester and plateau to term. Term cord sera TSH, TBG, and all iodothyronine levels, except T(3), are higher than nonpregnant women. In the third trimester, cord serum FT4, TSH, rT(3), and T4S levels are also higher than corresponding maternal levels, but T(4), T(3), and TBG levels are lower than maternal values. The late second/early third trimester is a critical transition period in fetal thyroid hormone metabolism, which may be interrupted by preterm birth and contribute to postnatal thyroid dysfunction.

The purpose of this study was to relate severity of illness at 1, 7, 14, and 28 postnatal days in preterm infants groups, 23-27 (n = 73), 28-30 (n = 160), and 31-34 (n = 208) wk gestation, to the corresponding sera levels of T(4), free T(4), T(4)-binding globulin, TSH, T(3), rT(3), and T(4) sulfate. The British Association of Perinatal Medicine and Neonatal Nurses Association 1992 scoring categories (published elsewhere) were used as an index of illness severity: level 1 (maximal intensive care) was compared with level 2 (high-dependency intensive care) combined with level 3 (special care); infants were scored on 1, 7, 14, and 28 postnatal days. In level 1 infants, there were significant reductions in T(3) at 7 d (28-30 wk), 14, and 28 d (23-27 and 28-30 wk); T(4) at 7, 14, and 28 d (23-27 wk); at 14 and 28 d (28-30 wk); and at 7 d (31-34 wk); and free T(4) at 14 d (23-27 wk). TSH was unchanged in all groups at all ages and with reductions in T(4) and T(3) being the key features of severe illness in extreme preterm infants.

Our findings do not support the view that the hypothyroxinemic state, in the context of this analysis, is harmless in preterm infants. Many factors contribute both to the etiology of hypothyroxinemia and neurodevelopment; strategies for correction of hypothyroxinemia should acknowledge its complex etiology and not rely solely on one approach.

Summary Background Faecal calprotectin decreases during exclusive enteral nutrition in children with active Crohn's disease. It is unknown how faecal calprotectin changes during food re‐introduction and the influence of maintenance enteral nutrition. Aims To study changes to faecal calprotectin during exclusive enteral nutrition and at food reintroduction, and explore associations with maintenance enteral nutrition. Methods Children with Crohn's disease were followed during exclusive enteral nutrition and during food‐reintroduction. Faecal calprotectin was measured before, at 33 and 54 days of exclusive enteral nutrition, and at 17, 52 and 72 days after food‐reintroduction. Maintenance enteral nutrition use was recorded with estimated weight food diaries. Data are presented with medians and Q1:Q3. Results Sixty‐six patients started exclusive enteral nutrition and 41 (62%) achieved clinical remission (weighted paediatric Crohn's disease activity index <12.5). Baseline faecal calprotectin (mg/kg) decreased after 4 and 8 weeks of exclusive enteral nutrition (Start: 1433 [Q1: 946, Q3: 1820] vs 33 days: 844 [314, 1438] vs 54 days: 453 [165, 1100]; P < .001). Within 17 days of food reintroduction, faecal calprotectin increased to 953 [Q1: 519, Q3: 1611] and by 52 days to 1094 [660, 1625] (both P < .02). Fifteen of 41 (37%) children in remission used maintenance enteral nutrition (333 kcal or 18% of energy intake). At 17 days of food reintroduction, faecal calprotectin was lower in maintenance enteral nutrition users than non‐users (651 [Q1: 271, Q3: 1781] vs 1238 [749, 2102], P = .049) and correlated inversely with maintenance enteral nutrition volume (rho: −0.573, P = .041), kcals (rho: −0.584, P = .036) and % energy intake (rho: −0.649, P = .016). Maintenance enteral nutrition use was not associated with longer periods of remission (P = .7). Faecal calprotectin at the end of exclusive enteral nutrition did not predict length of remission. Conclusions The effect of exclusive enteral nutrition on faecal calprotectin is diminished early during food reintroduction. Maintenance enteral nutrition at ~18% of energy intake is associated with a lower faecal calprotectin at the early phase of food reintroduction but is ineffective in maintaining longer term remission.

The use of thiopurine therapy in Epstein-Barr virus (EBV)-naı ¨ve inflammatory bowel disease (IBD) patients remains controversial due to a risk of EBV-associated complications. We evaluated EBV status and outcomes within our paediatric IBD population over an 8-year period; finding that 217 of 409 (53%) screened patients were seropositive for EBV at IBD diagnosis; that thiopurines were used in 189 of 217 (87%) seropositive and 159 of 192 (83%) seronegative patients (P ¼ 0.22); and that 7 of 192 (4%) previously seronegative patients subsequently tested positive for EBV with 6 of 7 (86%) patients having concurrently recorded thiopurine use. All six patients continued thiopurine with/without a period of cessation; no EBV-associated lymphoproliferative disorders/serious complications were recorded within our cohort. A significant proportion of our patients would not receive thiopurine therapy should their use be avoided in EBV-negative patients (47%) or seronegative males (30%). The small but significant risks of thiopurine treatment must be balanced against the potential benefits of successful IBD management; further research into this is required.

Background The anti-inflammatory effect of exclusive enteral nutrition on the gut of children with Crohn’s disease is rapidly lost after food reintroduction. This study assessed disease dietary triggers following successful treatment with exclusive enteral nutrition. Methods Nutrient intake, dietary patterns and dietary biomarkers in faeces (gluten immunogenic peptides, undigestible starch, short chain fatty acids) were assessed in 14 children with Crohn’s disease during early food reintroduction, following exclusive enteral nutrition. Groups above (Group A) and below (Group B) the median levels of faecal calprotectin after food reintroduction were assigned for comparative analysis. Results Intakes of fibre, gluten-containing cereals and red and processed meat were significantly higher in Group A than Group B; (median [Q1, Q3], g/day; Fibre: 12.1 [11.2, 19.9] vs. 9.9 [7.6, 12.1], p = 0.03; Red and processed meat: 151 [66.7, 190] vs. 63.3 [21.7, 67], p = 0.02; gluten-containing cereals: 289 [207, 402] vs. 203 [61, 232], p = 0.035). A diet consisting of cereals and meat products was predictive (92% accuracy) of higher faecal calprotectin levels after food reintroduction. In faeces, butyrate levels, expressed as absolute concentration and relative abundance, were higher in Group A than Group B by 28.4 µmol/g (p = 0.015) and 6.4% (p = 0.008), respectively. Levels of gluten immunogenic peptide and starch in faeces did not differ between the two groups. Conclusions This pilot study identified potential dietary triggers of gut inflammation in children with Crohn’s disease after food reintroduction following treatment with exclusive enteral nutrition. Trial registration: Clinical trials.gov registration number: NCT02341248; Clinical trials.gov URL: https://clinicaltrials.gov/ct2/show/NCT02341248 (retrospectively registered).

Thyroxine is essential for optimal brain development during gestation and for the first 2 years postnatally. Maintaining adequate thyroid hormone levels is vital, as low levels (even transiently low) are associated with adverse neurodevelopmental outcome. Thyroid hormone levels are gestationally age related, and levels vary appreciably between term infants and those born preterm; so much so, that interpretation of levels in preterm infants is most appropriately done against norms specific to the gestation at birth. Several factors, other than gestation, can alter levels of thyroid hormones, thyroid stimulating hormone/thyrotropin, and thyroid binding globulin; knowledge of these factors is helpful for interpretation and when considering the need for replacement therapy. This review focuses on preterm infants and describes the influences of gestation, critical illness, infection, specific neonatal conditions, prescribed drug usage, iodine deficiency, and iodine excess on levels of neonatal thyroid hormones, thyroid binding globulin, and thyroid stimulating hormone/thyrotropin.