Serum thyroid hormone and thyroid gland weight measurements in protein-energy malnutrition

Thyroid Hormone Function in Small for Gestational Age Term Newborns

OBJECTIVE

To test the hypothesis that term-born small for gestational age (SGA) neonates have elevated thyroid-stimulating hormone (TSH) concentrations and an increased incidence of congenital hypothyroidism compared with non-SGA term neonates.

STUDY DESIGN

This retrospective cohort study included all term neonates screened in Wisconsin in 2015 and 2016. The cohort was divided based on SGA status, defined as birth weight <10th percentile as calculated from the World Health Organization's sex-specific growth charts for age 0-2 years. TSH concentration on first newborn screening performed between birth and 96 hours of life and incidence of congenital hypothyroidism were compared between the SGA and non-SGA groups.

RESULTS

A total of 115 466 term neonates, including 11 498 (9.96%) SGA neonates, were included in the study. TSH concentration and incidence of congenital hypothyroidism was significantly higher in the SGA group, but only TSH concentration remained significant when adjusted for potential confounding variables.

CONCLUSIONS

Our data do not support a higher incidence of congenital hypothyroidism in term SGA neonates after adjusting for potential confounders. However, TSH concentrations were higher in term SGA neonates compared with term non-SGA neonates. The effects of mild thyroid hormone dysfunction on neurodevelopmental outcomes and development of chronic medical conditions merit long-term study.

The factors associated with transient hypothyroxinemia of prematurity

Background

Hypothyroxinemia is defined by low levels of thyroxine (T4) despite low or normal levels of thyroid-stimulating hormone (TSH). This study aimed to evaluate the factors associated with transient hypothyroxinemia of prematurity (THOP) in newborns admitted to the neonatal intensive care unit (NICU).

Method

This is a single center, retrospective, case-control study. Premature newborns, between 24 and 34 weeks of gestation, hospitalised between January 2014–December 2019 in Istanbul University-Cerrahpasa Faculty of Medicine NICU were analyzed through their medical records. Thyroid function tests were routinely performed between the 10th and 20th days of postnatal life and were evaluated according to the gestational age references. Thirty six possible associated factors (prenatal and postnatal parameters, medical treatments, clinical diagnoses and applications in NICU) were searched in the patient group with THOP (n = 71) and the control group with euthyroid prematures (n = 73). The factors for THOP were identified by univariate analysis, followed by multivariate analysis.

Results

Mean gestational ages of the study and the control groups were 29.7 ± 2.48 and 30.5 ± 2.30 weeks, respectively (p = 0.606). The birth weight, small for gestational age (SGA), intraventricular hemorrhage (IVH), congenital heart disease (CHD) were found to be the possible associated factors for THOP in the univariate analysis and CHD (p = 0.007, odds ratio [OR]:4.9, 95% confidence interval [CI]: 1.5–15.8), BW (p = 0.004, OR:0.999, 95% CI: 0.9–1.0) and SGA (p = 0.010, OR:4.6, 95% CI: 1.4–14.7) were found to be factors associated with THOP determined by univariate logistic regression analysis.

Conclusıons

Although some treatment practices might have had direct effects on pituitary–thyroid axis, related with the severity of the newborn clinical conditions, non of them was found to be a associated factor for THOP. However, CHD and SGA may be considered as associated factors with THOP detected in preterm infants.

Normal cortisol response to cold pressor test, but lower free thyroxine, after recovery from undernutrition

Undernutrition is a stressor with long-term consequences, and the effect of nutritional recovery on cortisol and thyroid hormone status is unknown. To investigate basal thyroid hormones and the cortisol response to a cold pressor test in children recovered from undernutrition, a cross-sectional study was undertaken on children (6–16 years) separated into four groups: control (n 41), stunted (n 31), underweight (n 27) and recovered (n 31). Salivary cortisol was collected over the course of 10 h: upon awakening, before and after an unpleasant and a pleasant stimulus. Cortisol upon awakening was highest in the stunted and lowest in the underweight groups: control=5·05 (95 % CI 3·71, 6·89) nmol/l, stunted=6·62 (95 % CI 3·97, 11·02) nmol/l, underweight=2·51 (95 % CI 1·75, 3·63) nmol/l and recovered=3·46 (95 % CI 2·46, 4·90) nmol/l (P=0·005). Girls had higher cortisol concentrations upon awakening compared with boys (P=0·021). The undernourished groups showed an elevated cortisol response both to the unpleasant stimulus and at the last measurement (16.00 hours) compared with that of the recovered group: AUC, control=2·07 (95 % CI 1·69, 2·45) nmol/l×30 min, stunted=2·48 (95 % CI 1·91, 3·06) nmol/l×30 min, underweight=2·52 (95 % CI 2·07, 2·97) nmol/l×30 min, recovered=1·68 (95 % CI 1·26, 2·11) nmol/l×30 min (P=0·042); and control=2·03 (95 % CI 1·75, 2·39) nmol/l×30 min, stunted=2·51 (95 % CI 1·97, 3·19) nmol/l×30 min, underweight=2·61 (95 % CI 2·16, 3·16) nmol/l×30 min, recovered=1·70 (95 % CI 1·42, 2·03) nmol/l×30 min (P=0·009). Lower free thyroxine (T4) was found in the recovered and stunted groups: control=1·28 (95 % CI 1·18, 1·39) pmol/l, stunted=0·98 (95 % CI 0·87, 1·10) pmol/l, underweight=1·10 (95 % CI 1·01, 1·21) pmol/l and recovered=0·90 (95 % CI 0·83, 0·99) pmol/l (P<0·001). Multivariate analysis showed a lower cortisol concentration along 10 h (06.00–16.00 hours) in the recovered compared with the other groups (P=0·017), and similar concentrations between the recovered and control group. In conclusion, the children with recovery in weight and height had a cortisol stress response similar to control but a lower basal free T4. Longitudinal studies are warranted to determine the extent of these endocrine changes after recovery of undernutrition and in adulthood.

Thyroid function in small for gestational age newborns: a review

Several studies have shown that small for gestational age (SGA) babies have a different hormonal profile than those born with a birth weight appropriate for gestational age (AGA). Thyroid hormones play an important role in growth and neurocognitive development. Only few studies analyzed the concentrations of thyroid-stimulating hormone (TSH) and thyroxine (T4) during fetal and extrauterine life in SGA and AGA newborns, and the existing data on the possible alterations of these hormones in postnatal life are controversial. It remains to be established whether SGA newborns have different blood concentrations of thyroid hormones as compared with AGA infants and if so, whether these findings play a role in the development of obesity, short stature, hypertension, and diabetes--disorders, already known to be related with SGA birth. It has also not yet been established whether and when substitutive therapy with levothyroxine (LT4) should be initiated in preterm and full-term SGA newborns. Further trials are needed to determine the thyroid hormone profile in both preterm and full-term SGA newborns and also to evaluate the effectiveness and safety of LT4 treatment in these infants.