Effect of maternal and neonatal factors on cord blood thyroid stimulating hormone

Neonatal TSH as a marker of iodine nutrition status. Effect of maternal ioduria and thyroid function on neonatal TSH

INTRODUCTION

Neonatal thyroid stimulating hormone (nTSH) is a marker of iodine nutrition status in the population. The WHO considers a prevalence of less than 3% of nTSH levels greater than 5 mIU/L in samples obtained within 72h from birth indicative of iodine sufficiency. The aim of this study was to determine the prevalence of nTSH levels greater than 5 mIU/L in an iodine-sufficient population and its association with maternal, neonatal and obstetric factors.

MATERIALS AND METHODS

A total of 243 pregnant women were recruited between May and June 2017 in our health area. A questionnaire of iodine intake was administered, in addition to determination of ioduria, thyroid function and autoimmunity in the first trimester of gestation. We analysed nTSH levels in samples collected between 48 and 72h post birth and other obstetric and neonatal factors.

RESULTS

The mean nTSH level (standard deviation) was 2.43 (1.68 mIU/L), with 7.8% of neonates having levels greater than 5 mIU/L. The highest nTSH levels corresponded to neonates of mothers with insufficient ioduria (P = 0.021) or TSH levels greater than 2.5 mIU/L, in both the case of negative (P = 0.049) and positive (P = 0.006) thyroid autoimmunity results. Maternal ioduria less than 150 μg/L was a risk factor for nTSH levels greater than 5 mIU/L (3.70 [1.06-14.60]; P = 0.046), while a neonatal weight of 2500 g or greater was a protective factor (0.14 [0.02-1.00]; P = 0.038).

CONCLUSIONS

The prevalence of nTSH levels greater than 5 mIU/L in our health area was high based on the WHO recommendations. Maternal iodine deficiency was associated with a higher risk of nTSH levels greater than 5 mIU/L. Given that nTSH is currently measured before 72h post birth, we need new cut-off points to keep on using nTSH as a marker of iodine nutritional status.

Congenital hypothyroidism in India: A systematic review and meta-analysis of prevalence, screen positivity rates, and etiology

Background

Congenital hypothyroidism (CH) is the leading cause of preventable mental retardation, which is currently not universally screened in India. Knowledge of the country-specific prevalence of the disease can guide in establishing a universal screening program.

Methods

We performed a systematic review and meta-analysis to assess the prevalence, screen positivity rates, compliance to recall and etiology of CH in India. The databases of PubMed, Embase, Google scholar and IMSEAR were searched on 1^st October 2021. All observational studies reporting at least one of the outcomes of interest were included. Two reviewers independently extracted the data and appraised the quality of studies using the Joanna Briggs tool for prevalence studies. Estimates were pooled using a random-effects model with double arcsine transformation (MetaXL software). PROSPERO database registration number was CRD42021277523.

Findings

Of the 2 073 unique articles retrieved, 70 studies were eligible for inclusion. The prevalence of CH (per 1 000 neonates screened) was 0·97 (95% confidence intervals/CI: 0·9, 1·04) in non-endemic areas (54 studies and 819 559 neonates), 79 (95% CI: 72, 86) in endemic areas (3 studies, 5 060 neonates), 50 (95% CI: 31, 72) in neonates born to mothers with thyroid disorders, and 14 (95% CI: 8, 22) in preterm neonates. At thyroid stimulation hormone cut-off of 20 mIU/L, the screen positivity rates were 5·6% (95% CI: 5·4%, 5·9%) for cord blood samples and 0·19% (95% CI: 0·18%, 0·2%) for postnatal sample. About 70% (95% CI: 70, 71) of screen positive neonates were retested with diagnostic tests. Among neonates with permanent hypothyroidism, thyroid dysgenesis 56·6% (95% CI: 50·9%, 62·2%) was more common than dyshormonogenesis 38·7% (95% CI: 33·2%, 44·3%).

Interpretation

The prevalence of congenital hypothyroidism in India is higher than global estimates. Screen positivity rate was higher for cord blood screening when compared to postnatal screening. Compliance with confirmatory testing was higher for cord blood screening.

Funding

The study was not funded by any source.

Effect of Maternal Triclosan Exposure on Neonatal Thyroid-Stimulating Hormone Levels: A Cross-Sectional Study

Objective

This study is aimed at assessing the relationship between maternal urinary triclosan (uTCS) exposure and the thyroid-stimulating hormone (TSH) level of infant cord blood.

Methods

This cross-sectional study was carried out in 2019-2020 in Isfahan, Iran, and 99 pregnant women participated in the study. Urine samples were collected after the 28th week of pregnancy, and the concentration of TCS was measured using GC/MS. The cord blood levels of TSH (CBL-TSH) were measured. The association between uTCS and CBL-TSH was examined based on the general linear model.

Results

TCS was detected (≥0.01 ng/mL) in 100% of the urine samples, with the interquartile range (25%-75%) of uTCS levels 0.6-6.23 μg/g Cr. uTCS was not associated with CBL-TSH after adjustment for covariates. A significant relationship was observed between CBL-TSH of neonates born to mothers who had given birth only once compared to mothers who had given birth twice or more times.

Conclusions

Maternal exposure to TCS did not affect the infant CBL-TSH. However, the high concentrations of TCS in maternal urinary samples indicate the necessity of more precise regulations to decrease the use of this chemical in the industry and increase public awareness about using TCS-free compounds.

Higher maternal thyroid resistance indices were associated with increased neonatal thyroid-stimulating hormone- analyses based on the Huizhou mother-infant cohort

OBJECTIVES

This study aimed to explore the relationship of maternal thyroid function and thyroid resistance parameters with neonatal thyroid-stimulating hormone (TSH).

METHODS

This work was a longitudinal study. Singleton pregnant women without a history of thyroid disorders were recruited in their first prenatal visit from October 2018 to June 2020. Maternal thyroid markers including TSH, free triiodothyronine (FT3), free thyroxine (FT4), and neonatal TSH were tested in the clinical laboratory of the hospital by electrochemiluminescence immunoassay. Thyroid resistance indices including Thyroid Feedback Quantile-based Index (TFQI), TSH index (TSHI), and thyrotroph T4 resistance index (TT4RI) were estimated in accordance with maternal FT4 and TSH levels. Multivariable linear and logistic regression was applied to explore the associations of maternal thyroid indices with infantile TSH level.

RESULTS

A total of 3,210 mothers and 2,991 newborns with valid TSH data were included for analysis. Multivariable linear regression indicated that maternal thyroid variables were significantly and positively associated with neonatal TSH levels with standardized coefficients of 0.085 for TSH, 0.102 for FT3, 0.100 for FT4, 0.076 for TSHI, 0.087 for TFQI, and 0.089 for TT4RI (all P < 0.001). Compared with the lowest quartile, the highest quartile of TSHI [odds ratio (OR) = 1.590, 95% CI: 0.928-2.724; P_trend = 0.025], TFQI (OR = 1.746, 95% CI: 1.005-3.034; P_trend = 0.016), and TT4RI (OR = 1.730, 95% CI: 1.021-2.934; P_trend = 0.030) were significantly associated with an increased risk of elevated neonatal TSH (>5 mIU/L) in a dose-response manner.

CONCLUSION

The longitudinal data demonstrated that maternal thyroid resistance indices and thyroid hormones in the first half of gestation were positively associated with neonatal TSH levels. The findings offered an additionally practical recommendation to improve the current screening algorithms for congenital hypothyroidism.

A detailed observational study of maternal and neonatal variables affecting the thyroid-stimulating hormone levels in neonates

Background

Thyroid hormones are essential for fetal growth and the central nervous system development. Thyroid-stimulating hormone (TSH) is the key regulatory hormone. Their levels are quite dynamic in the perinatal period and are influenced by multiple factors. These factors should be taken into consideration during newborn screening. This study aimed to observe the impact of maternal and neonatal factors on neonatal TSH status.

Results

Neonatal TSH (nTSH) depicted a positive correlation with parity (p = 0.066) while negative correlation recorded with maternal blood haemoglobin (p = 0.007) among maternal factors.

New-born length (p = 0.027) and birth weight (p < 0.001) exhibited a negative correlation with nTSH among neonatal factors.

Conclusions

This study concludes that among all the maternal and neonatal factors, birth weight shows the most influence on nTSH. However, the effect may be compounded by other factors. As these risk elements rarely occur singly, it is often difficult to find the exposure which confer the risk on children. These factors should be considered while interpreting the result of the screening program.

Utility of the New Indian Society of Paediatric and Adolescent Endocrinology (ISPAE) Guidelines for Congenital Hypothyroidism Screening in a High Risk Unit

OBJECTIVE

To study the new ISPAE guidelines in neonates with congenital hypothyroidism and present authors' experience in managing these neonates.

METHODS

A retrospective review of all babies who were screened for congenital hypothyroidism in the institution over a period of 5 y was conducted. Details pertaining to maternal risk factors, neonatal risk factors, screening TSH, venous TSH and details of etiological evaluation including: ultrasound thyroid, technetium 99m scintigraphy and anti thyroid peroxidase antibody estimation were retrieved. The cases were assessed using the new ISPAE guidelines.

RESULTS

During the study period, 8107 babies were screened for congenital hypothyroidism, 83 cases had confirmed disease and 47 had established etiology. There is a fair correlation between screening TSH and venous TSH (r = 0.7, p < 0.05). The estimated incidence of congenital hypothyroidism in present series is 1 in 97 cases. Out of the 83 cases, 36 (43.3%), 16 (19.2%) and 31 (37.3%) cases had screening TSH >20 μIU/mL, 6-20 μIU/mL and < 6 μIU/mL, respectively. Out of the 47 babies with screening TSH <20 μIU/mL, 23 (48.9%), 25 (53.1%) and 12 (25.5%) cases had prematurity, maternal thyroid disease and illness, respectively, as risk factors (some babies had more than one risk factor). Of the 83 cases, all of them had venous TSH >10 μIU/mL and five cases had low Free T4 (<1.1 ng/dl). Thus, none of the cases with congenital hypothyroidism were missed on the new ISPAE guidelines.

CONCLUSION

The new ISPAE guidelines for neonatal screening for congenital hypothyroidism are very useful and applicable in Indian neonates.

Delivery factors and neonatal thyroid hormone levels: a systematic review

Postnatal thyroid hormone changes enable the neonate to be adapted for postnatal life. Several factors can affect this adaption. In this review, we summarized the studies that reported the association among the delivery factors and neonatal thyroid hormones and thyroid stimulating hormone. A comprehensive literature search was performed in PubMed, Web of Science, and Scopus up to March 2020, to identify the studies investigating the relationship between delivery factors, especially the mode of delivery and labor pain, and neonatal thyroid hormones and TSH. Finally, in this review study, of 157 articles obtained in the initial search, 25 eligible studies were reviewed. Various maternal, fetal/neonatal, and obstetric factors affected neonatal TSH and thyroid hormones. Among various influencing factors, mode of delivery, labor pains, and duration of labor have a strong relationship with neonatal thyroid hormones and need to be considered for interpretation of neonatal thyroid status. The majority of the studies revealed that vaginal deliveries (instrumental or natural) lead to higher levels of cord TSH compared to elective cesarean section. This can be explained by the increased secretion of catecholamine during labor. It has been suggested that blood TSH and thyroid hormone levels are affected by perinatal stress events such as maternal anxiety, labor pains, fetal distress, and other stimulants of the catecholamine response. These changes may act as the trigger to increase thyroid hormone levels for adapting of neonates in the first hours after birth. This assumption needs to be re-evaluated by performing comprehensive and well-designed studies.

Impact of maternal thyroid disease on neonatal thyroid status

OBJECTIVES

Prevalence of Maternal and congenital hypothyroidism is on the rise. To present the thyroid stimulating hormone screening results in babies born to hypothyroid mothers and assess the burden, aetiology of hypothyroidism in these babies.

METHODS

All antenatal mothers attending our hospital during the study period were enrolled into the study. Group I includes 249 term babies born to hypothyroid mothers and group II comprises 2154 newborns born to mothers who are euthyroid. Heel prick thyroid stimulating hormone was done for all newborns on day 3 for both groups. Confirmatory venous testing was done for all for babies in group I and screen positives belonging to group II. Evaluation and therapy done as per standard guidelines.

RESULTS

Thyroid stimulating hormone values in the two groups are presented. There was significant correlation between peak maternal thyroid stimulating hormone and neonatal day 3 heel prick in group I (r=0.7, P<0.05). The prevalence of positive screening test in groups I and II was 3.8 and 1.03% (p<0.05) whereas corresponding values for confirmed disease was 4.3 and 0.6%, respectively (p<0.05). Aetiological evaluation revealed both transient hypothyroidism (33.3%) and permanent hypothyroidism (66.6%).

CONCLUSION

4.3% of babies born to hypothyroid mothers develop congenital hypothyroidism; aetiology being both transient and permanent. A venous test by 3 weeks is helpful in these babies to improve case identification.

Diagnostic Utility of Cord Blood Thyroid Stimulating Hormone in Congenital Hypothyroidism in the Era of Expanded Newborn Screening

Even in the era of expanded newborn screening, utility of cord blood thyroid stimulating hormone (cTSH) for diagnosis of congenital hypothyroidism (CH) cannot be marginalised. This study was to assess the diagnostic utility of cTSH > 20 μIU/L for screening CH. Generation of new cTSH value was the main outcome measure, to increase specificity. Designed as a cross-sectional analytic study in the neonatal unit of teaching hospital, 1200 term neonates with birth weight ≥2500 g, with no perinatal complications were included. Newborn cTSH assay was done by chemi-luminescence. All screen positive were followed up on day five, 14 and 28 of life, to rule in or out CH (true or false positive). Positive predictive value and specificity were calculated. Receiver operating characteristic (ROC) was done to assess diagnostic accuracy of cTSH > 20 μIU/L and to ascertain new cut-off to reduce false positivity. Of 1200 newborns screened, 69 (5.8%) were screen positive and followed up. In five, CH was confirmed (true positive); one in 240 newborns required thyroxine therapy. False positivity was noted in 59. Recall and dropouts were 6.25 and 7.2% respectively. Median cTSH of screen, true and false positives were 28.8, 43.5 and 27.2 μIU/L respectively. Comparison of median values of cord blood (U = 59; p = 0.017) and day five serum TSH (U = 0.0; p < 0.001) among true and false positive subjects were statistically significant. Specificity calculated was 94.6% and positive predictive value 7.25%. ROC generated new permissible cTSH cut-off value of 30 μIU/L. In conclusion, an extended cTSH cut-off value of 30 μIU/L improves specificity.

Perinatal factors associated with neonatal thyroid-stimulating hormone in normal newborns

PURPOSE

This study was to evaluate the effect of neonatal, maternal, and delivery factors on neonatal thyroid-stimulating hormone (TSH) of healthy newborns.

METHODS

Medical records of 705 healthy infants born through normal vaginal delivery were reviewed. Neonatal TSH levels obtained by neonatal screening tests were analyzed in relation to perinatal factors and any associations with free thyroxine (FT4) and 17-α hydroxyprogesterone (17OHP) levels.

RESULTS

An inverse relationship was found between TSH and sampling time after birth. Twin babies and neonates born by vacuum-assisted delivery had higher TSH levels than controls. First babies had higher TSH levels than subsequent babies. Birth weight, gestational age, maternal age and duration from the rupture of the membrane to birth were not related to neonatal TSH. There were no significant differences in TSH level according to sex, Apgar scores, labor induction, the presence of maternal disease and maternal medications. There was a positive association between TSH and 17OHP level but not between TSH and FT4 level. Multiple linear regression analyses showed that sampling time, mode of delivery, birth order, and 17OHP level were significant factors affecting neonatal TSH level.

CONCLUSION

Neonatal TSH levels of healthy normal newborns are related with multiple factors. Acute stress during delivery may influence the neonatal TSH level in early neonatal period.