Neonatal Thyroid-stimulating Hormone Levels Research Articles

A Randomized Controlled Trial of the Correlation between Iodine Supplementation in Pregnancy and Maternal Urine Iodine and Neonatal Thyroid Stimulating Hormone Levels

Objective: To establish the correlation of maternal urine iodine and neonatal thyroid stimulating hormone (TSH) in iodine supplemented and non-iodine supplemented pregnant women. Materials and Methods: The study was a prospective, randomized, controlled trial, which was conducted at the antenatal care unit, labor ward, and neonatal unit of Siriraj Hospital, Mahidol University, Bangkok, Thailand. In all, 224 pregnant women were recruited during 1 October 2015 and 31 July 2017. They were randomized into 2 groups: an iodine and a non-iodine supplemented group. One woman in the control group left the study as she had delivery at another hospital. Results: There were no statistically significant differences in the demographic data, original area of domicile, and adverse neonatal outcomes (including preterm labor and low birth weight) of the patients in the two groups. The maternal urinary iodine levels were 84.14 + 61.85 and 58.41 + 41.36 microgram/L, and the median values of the neonatal TSH levels were 3.7 + 1.87 and 4.4 + 1.99 mIU/ml, in the iodine and non-iodine supplemented groups, respectively. The differences in both values were statistically significant (p-value < 0.05). Conclusion: This study determined that there were statistically significant differences in the maternal urinary iodine levels and the median values of the neonatal TSH levels of the iodine and non-iodine replacement groups of pregnant women. Even though there were no clinically significant differences and none of the newborns was diagnosed with hypothyroidism, iodine supplementation in all pregnant women should be considered. A larger prospective, RCT trial would confirm the benefits of a strategy of routinely administering iodine to pregnant women at Siriraj Hospital.

Neonatal Thyroid-Stimulating Hormone Screening as a Monitoring Tool for Iodine Deficiency in Turkey.

Objective:Thyroid-stimulating hormone (TSH) level in neonates is recommended as an indicator for presence of iodine deficiency (ID) at a population level and as a monitoring tool in programs of iodine supplementation. The purpose of this study, based on data from the National Newborn Screening Program (NNSP) for congenital hypothyroidism (CH) in 2014, was to analyze neonatal TSH levels to predict the current status of iodine nutrition in Turkey.Methods:According to screening methodology, heel-prick blood samples of newborns were collected on filter paper cards usually on day 3-5 after birth (or shortly before discharge). Results of samples collected >48 h after birth were analyzed. The degree of severity of ID was assessed by using the epidemiologic criteria of the World Health Organization (WHO). Elevated TSH levels (>5 mIU/L) were processed and classified according to province, region, birth season, and sampling time.Results:A total of 1,298531 newborns were registered in the NNSP for the CH database. Of those, 1,270311 newborns had screening results collected >48 h after birth and were included in the statistical analyses. The national prevalence of elevated TSH was 7.2%. While the Gaziantep sub-region had the highest TSH elevation rate (15.9%), the Tekirdağ sub-region had the lowest rate (4.0%; p<0.001). Seasonal variations were also significant, and the elevated TSH prevalence rate was highest in winter (7.4%; p<0.001).Conclusion:National CH screening results suggest that Turkey may still be mildly iodine deficient. Nationwide studies should be performed for direct assessment and monitoring of iodine status in vulnerable populations to confirm accuracy of our results.

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

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

The Study on Thyroid Status among Newborns in Jaffna District in Sri Lanka

Iodine is an essential nutrient for the production of thyroid hormones triiodothyronine (T3) and thyroxine (T4). A woman needs more iodine during pregnancy to maintain normal metabolism as well as to meet the requirements of T4 and iodide transfer to the fetus. Objective of this study was to assess the thyroid status among newborns in Jaffna District, because similar studies conducted nationally, but not in Jaffna and no data is available about the thyroid status of the neonates. Randomly selected 477 newborns in six Medical Officers of Health (MOH) Divisions out of twelve were studied.Blood spots were taken from the neonates within the one week of delivery on specified filter paper and thyroid stimulating hormone (TSH) was assayed by using enzyme-linked immunosorbent assay(ELISA)/Radioimmunoassay (RIA) technique depending on availability of the kits in the laboratory. Among the total newborns, 239 were males (50.5%). Mean birth weight (BW) of them was 3031.5(±432.6) g, while the mean length was 51.1 (±2.1) cm. BW of males ranged from 1.7 to 5.0 Kg and of females from 1.5 to 4.35 Kg. Length of the newborns ranged from 45.0 to 58.0cm for males and from 44.0 to 57.0cm for females. The low birth weight (LBW), normal birth weight (NBW) and higher birth weight (HBW) were 11.3 (n=54), 88.5 (n=422) and 0.2% (n=1) respectively. Mean neonatal blood spot TSH concentration was 9.8 (±2.1) mIU/L, and ranged from 1.00 to 53.46 mIU/L. Neonatal TSH level of the entire blood spot was categorized as > 20 mIU/L and < 20 mIU/L and the blood spot TSH > 20 mIU/L was considered as positive for congenital hypothyroidism. Among the newborns, 18% (n=86) of them were identified as positive with 10% males and 8% females. Only one newborn was diagnosed as being congenitally hypothyroid (serum TSH >9.8 mIU/L and free T4< 10pmol/L) with very high blood spot TSH value of 360.91 mIU/L. Further, a higher prevalence (37.7%) of neonates with blood spot TSH >5 mIU/Lwas observed in this study.

Neonatal thyroid-stimulating hormone level is influenced by neonatal, maternal, and pregnancy factors

The percentage of newborns with a neonatal whole blood thyroid-stimulating hormone (TSH) greater than 5 mIU/L has been used as an indicator of iodine deficiency at the population level. However, TSH levels in newborns may be influenced by many factors other than iodine status. The objective of this study was to identify neonatal, maternal, and pregnancy-related determinants of neonatal TSH levels in a retrospective cohort study. The study sample included 313 Belgian mothers and their 4- to 5-year-old children. The children had a neonatal TSH concentration between 0 and 15 mIU/L at neonatal screening, and blood samples were collected 3 to 5 days after birth. Children with suspected congenital hypothyroidism (neonatal TSH level >15 mIU/L), prematurely born (ie, <37 weeks), or with a low birth weight (ie, <2500 g) were excluded. Information about maternal and birth-related determinants was collected from the neonatal screening center via a self-administered questionnaire filled in by the mother together with the child's health booklet. Higher TSH levels were found in spring and winter compared to summer and autumn (P = .011). Higher TSH levels were associated with lifetime smoking behavior (up to child birth) in the mother (P = .005), lower weight gain during pregnancy (P = .014), and longer pregnancies (P = .003). This study showed that several neonatal, maternal, and pregnancy-related determinants are influencing neonatal TSH level.

The evaluation of transient hypothyroidism in patients diagnosedwith congenital hypothyroidism

Congenital hypothyroidism (CH) is divided into two groups as 'permanent' and 'transient' We aimed to determine the rate of transient and permanent congenital hypothyroidism of the newborns referred to our clinic. Of the newborns who were referred to our clinic from the neonatal screening program, those who were diagnosed with CH and started treatment were included in the study. The treatments of the patients whose required daily treatment dose was reduced to under 1 µg/kg were terminated and those who were followed monthly and whose fT4 and thyroid-stimulating hormone (TSH) levels were normal at least 3 times without treatment were considered to have transient hypothyroidism. Of the 256 newborns referred to our clinic from the neonatal screening program, 114 (44.5%) were diagnosed with CH. Of the CH patients, 70% (n = 58) were evaluated to have permanent and 30% (n = 25) transient hypothyroidism. Neonatal and serum TSH levels and treatment doses were found to be significantly lower in the transient hypothyroidism patients. Initial measurements of the serum TSH level and the required doses of L-thyroxine therapy for maintaining normal thyroid hormone levels, growth, and development may have a predictive role for differentiating permanent forms of CH from transient forms.

Using record linkage to investigate perinatal factors and neonatal thyroid-stimulating hormone.

Studies examining the relationship between maternal and infant thyroid parameters have shown conflicting results. Record linkage provides an opportunity to examine the association between maternal and infant thyroid-stimulating hormone (TSH) levels. Our aim was to demonstrate the feasibility of record linkage of newborn screening (NBS), laboratory and birth databases for research by investigating the association between maternal and newborn TSH levels. The records of 2802 women with first trimester serum TSH concentrations were linked with population-based birth data and NBS data containing infant TSH levels. Association between moderately high neonatal TSH levels (>5 mIU/L) and maternal and infant characteristics was evaluated. The correlation and association between maternal and infant TSH levels were assessed using Pearson's correlation coefficient and multivariable linear regression, respectively. Of maternal and birth records, 99.3% linked with an NBS record. Mother's country of birth, gestational age (>41 weeks) and lower birthweight were associated with neonatal TSH levels >5 mIU/L. Neonatal and maternal first trimester TSH levels were not correlated, although statistically significant (r = 0.05, P = 0.008). The association between neonatal TSH and maternal TSH, after adjusting for maternal age, gestational age and age at NBS testing, was also small (b = 0.039, P = 0.009). Record linkage is a feasible and cost-efficient way to investigate the association between maternal factors and neonatal hormone levels. First trimester maternal thyroid levels are not correlated with neonatal TSH levels. This method of outcome assessment can be used for future research examining long-term outcomes for infants with different NBS results.

Prenatal and neonatal thyroid stimulating hormone levels and autism spectrum disorders.

Thyroid hormones are critical for normal brain development. This study examined autism spectrum disorders (ASD) and thyroid stimulating hormone (TSH) levels measured in mid-pregnancy maternal serum and infant blood after birth. Three groups of children born in Orange County, CA in 2000-2001 were identified: ASD (n = 78), developmental delay (n = 45), and general population controls (GP) (n = 149). Samples were retrieved from prenatal and newborn screening specimen archives. Adjusted logistic regression models showed inverse associations between ASD and log transformed TSH levels in maternal serum samples (ASD vs. GP: OR [95 % CI] 0.33 [0.12-0.91], Early Onset ASD vs. GP: 0.31 [0.10-0.98]). Results for thyroid levels in newborn blood samples were similar though not significant (ASD vs. GP: 0.61 [0.18-2.04]).

Protocol of the PSYCHOTSH study: association between neonatal thyroid stimulating hormone concentration and intellectual, psychomotor and psychosocial development at 4-5 year of age: a retrospective cohort study.

BackgroundSeveral European countries, including Belgium, still suffer from mild iodine deficiency. Thyroid stimulating hormone (TSH) concentration in whole blood measured at birth has been proposed as an indicator of maternal iodine status during the last trimester of pregnancy. It has been shown that mild iodine deficiency during pregnancy may affect the neurodevelopment of the offspring. In several studies, elevated TSH levels at birth were associated with suboptimal cognitive and psychomotor outcomes among young children. This paper describes the protocol of the PSYCHOTSH study aiming to assess the association between neonatal TSH levels and intellectual, psychomotor and psychosocial development of 4–5 year old children. The results could lead to a reassessment of the recommended cut-off levels of 5 > mU/L used for monitoring iodine status of the population.MethodsIn total, 380 Belgian 4–5 year old preschool children from Brussels and Wallonia with a neonatal blood spot TSH concentration between 0 and 15 mU/L are included in the study. For each sex and TSH-interval (0–1, 1–2, 2–3, 3–4, 4–5, 5–6, 6–7, 7–8, 8–9 and 9–15 mU/L), 19 newborns were randomly selected from all newborns screened by the neonatal screening centre in Brussels in 2008–2009. Infants with congenital hypothyroidism, low birth weight and prematurity were excluded from the study. Neonatal TSH concentration was measured by the Autodelphia method in dried blood spots, collected by heel stick on filter paper 3 to 5 days after birth. Cognitive abilities and psychomotor development are assessed using the Wechsler Preschool and Primary Scale of Intelligence - third edition - and the Charlop-Atwell Scale of Motor coordination. Psychosocial development is measured using the Child Behaviour Check List for age 1½ to 5 years old. In addition, several socioeconomic, parental and child confounding factors are assessed.ConclusionsThis study aims to clarify the effect of mild iodine deficiency during pregnancy on the neurodevelopment of the offspring. Therefore, the results may have important implications for future public health recommendations, policies and practices in food supplementation. In addition, the results may have implications for the use of neonatal TSH screening results for monitoring the population iodine status and may lead to the definition of new TSH cut-offs for determination of the severity of iodine status and for practical use in data reporting by neonatal screening centres.

Maternal factors and complications of preterm birth associated with neonatal thyroid stimulating hormone.

Thyroid hormones are important regulators of fetal neurodevelopment. Among preterm infants, thyroid stimulating hormone (TSH) is highly variable. Understanding this variability will further improvements in screening for thyroid disorders in preterm infants. We examined 61 maternal and infant clinical and demographic factors for associations with neonatal TSH levels in 698 preterm neonates. TSH was measured as part of routine State-mandated newborn screening in Iowa. Of the maternal characteristics, nulliparous women (p=8×10-4), women with preeclampsia (p=2×10-3), and those with induced labor (p=3×10-3) had infants with higher TSH levels. TSH levels at the time of newborn screening were associated with respiratory distress syndrome (RDS) (p<0.0001) and sepsis (p=3×10-3). We replicated findings between parity and preeclampsia previously observed in primarily term infants. We also observed strong relationships between neonatal TSH and complications of prematurity including RDS and sepsis, which have implications for future studies examining this relationship both prenatally and longitudinally after birth.

Maternal and Neonatal Urinary Iodine Status and its Effect on Neonatal TSH Levels in a Mildly Iodine-Deficient Area

Objective: Iodine deficiency and excess are the most important factors that affect screening and recall rates of congenital hypothyroidism. The purpose of this study was to investigate the urinary iodine status in newborns and their mothers and its effects on neonatal thyroid-stimulating hormone (TSH) levels in a mildly iodine-deficient area.Methods: A total of 116 newborns and their mothers were included in the study. Urinary iodine levels were measured from healthy mothers and their babies on the 5th day following birth. Neonatal TSH levels were screened, and TSH and free thyroxine (fT4) levels were measured on the15th day in the recall cases. T4 treatment was started in infants with high TSH and low fT4 levels. These measurements were repeated on the 30th day in these newborns.Results: Ninety-nine percent of the mothers included in the study were using iodized salt. The median urinary iodine level in the newborns was 279 µg/L, while it was 84 µg/L in their mothers. The rate of iodine deficiency among the mothers was 56.8%, and the rate of iodine excess was 8.6%. This rate was 10.3% for iodine deficiency and 61.2% for iodine excess in the newborns. The recall rate at the screening was 9.5% (n=11). The urinary iodine levels were above 200 µg/L in three newborns who had transient hyperthyrotropinemia.Conclusions: Iodine deficiency was more frequently observed in nursing mothers, and iodine excess was more frequently seen in their newborns. The iodine excess noted in the newborns was attributed to the use of antiseptics containing iodine. The iodine excess leads to increases in recall rates, screening costs, and frequency of transient hyperthyrotropinemia.Conflict of interest:None declared.

Genetic associations with neonatal thyroid-stimulating hormone levels

BackgroundElevations or deficits in thyroid hormone levels are responsible for a wide range of neonatal and adult phenotypes. Several genome-wide, candidate gene and meta-analysis studies have examined thyroid hormones in adults; however, to our knowledge no genetic association studies have been performed with neonatal thyroid levels.MethodsA population of Iowa neonates; term (n=827) and preterm (n=815), were genotyped for 45 single nucleotide polymorphisms. Thyroid stimulating hormone (TSH) values were obtained from the Iowa Neonatal Metabolic Screening Program. Analysis of variance was performed to identify genetic associations with TSH concentrations.ResultsThe strongest association was rs4704397 in the PDE8B gene (p=1.3×10−4), followed by rs965513 (p=6.4×10−4) on chromosome 9 upstream of the FOXE1 gene. Both of these SNPs met statistical significance after correction for multiple testing. Six other SNPs were marginally significant (p<0.05).ConclusionsWe demonstrated for the first time two genetic associations with neonatal TSH levels that replicate findings with adult TSH levels. These SNPs should be considered as early predictors of risk for adult diseases and conditions associated with thyroid hormone levels. Furthermore, this provides a better understanding of the thyroid profile and potential risk for thyroid disorders in newborns.

Neonatal Thyroid-Stimulating Hormone Concentrations in Belgium: A Useful Indicator for Detecting Mild Iodine Deficiency?

It has been proposed that neonatal thyroid-stimulating hormone (TSH) concentrations are a good indicator of iodine deficiency in the population. A frequency of neonatal TSH concentrations above 5 mU/L below 3% has been proposed as the threshold indicating iodine sufficiency. The objective of the present study was to evaluate feasibility and usefulness of nation-wide neonatal TSH concentration screening results to assess iodine status in Belgium. All newborns born in Belgium during the period 2009–2011 (n = 377713) were included in the study, except those suffering from congenital hypothyroidism and premature neonates. The frequency of neonatal TSH concentrations above 5 mU/L from 2009 to 2011 in Belgium fluctuated between 2.6 and 3.3% in the centres using the same TSH assay. There was a significant inverse association between neonatal TSH level and birth weight. The longer the duration between birth and screening, the lower the TSH level. Neonatal TSH levels were significantly lower in winter than in spring or autumn and significantly lower in spring and summer than in autumn while significantly higher in spring compared to summer. In conclusion, despite that pregnant women in Belgium are mildly iodine deficient, the frequency of neonatal TSH concentrations above 5 mU/L was very low, suggesting that the neonatal TSH threshold proposed for detecting iodine deficiency needs to be re-evaluated. Although neonatal TSH is useful to detect severe iodine deficiency, it should not be recommended presently for the evaluation of iodine status in mildly iodine deficient regions.

Prenatal Exposure to Polybrominated Diphenyl Ether Flame Retardants and Neonatal Thyroid-Stimulating Hormone Levels in the CHAMACOS Study

Studies published in the last 3 decades have demonstrated global human exposure to polybrominated diphenyl ether (PBDE) flame retardants. A growing body of literature suggests that PBDEs may disrupt thyroid hormone homeostasis. Although thyroid hormones play an essential role in brain development, few studies have investigated relations between prenatal exposure to PBDEs and neonatal thyroid hormone levels, and none have measured thyroid-stimulating hormone (TSH) levels in neonates. The authors measured 10 PBDE congeners in serum collected between October 1999 and October 2000 from 289 pregnant women living in California's Salinas Valley and abstracted TSH levels from their children's medical records. Individual PBDE congeners showed null or weak nonsignificant inverse relations with neonatal TSH. Total serum PBDE was not associated with neonatal TSH (β = 0.00, 95% confidence interval: -0.06, 0.06). Except for brominated diphenyl ether 153, a higher serum PBDE level was related to elevated odds of high TSH (≥80th percentile), but associations were not statistically significant. Associations were not modified by infant sex, age at TSH measurement, maternal serum polychlorinated biphenyl concentration, or mode of delivery. Results were robust to sensitivity analysis. The authors found no conclusive evidence that prenatal exposure to PBDEs at levels similar to those of the general US population is related to neonatal TSH.

EXPOSURE TO BISPHENOL A DURING PREGNANCY AND MATERNAL AND NEONATAL THYROID HORMONE LEVELS

Background and Aims: Bisphenol A (BPA) is widely used in the manufacture of polycarbonate bottles, food packaging, can linings, and dental sealants. High detection frequencies in numerous environmental and human specimens indicate that BPA is a widespread contaminant. Animal and in vitro studies suggest that BPA may disrupt thyroid hormone (TH) but little human data are available, particularly in pregnant women and neonates. Normal thyroid function during these critical developmental periods is essential for normal brain development. Our aim was thus to determine whether maternal exposure to BPA is related to thyroid hormone levels in pregnant women and neonates. Methods: We measured BPA in urine samples collected during the first and second half of pregnancy in women participating in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS). Pregnant women who were &gt;=18 years, &lt;20 weeks gestation, English or Spanish speaking, and qualified for Medicaid (health insurance for low-income families) were eligible for participation in the study. Free thyroxine (T4), total T4 and thyroid-stimulating hormone (TSH) was measured in 339 maternal serum samples obtained at ~27 weeks’ gestation. Neonatal TSH levels were abstracted from medical records (n=371). Results: The median BPA urinary concentration was lower in CHAMACOS women (1.1 µg/L) than in the general U.S. population (2.8 µg/L). Preliminary analyses suggest that every 10-fold increase in maternal BPA urinary concentration in the second, but not the first, half of pregnancy was associated with a 0.5 µg/dL decrease in total T4 (95%CI=-1.0, -0.1) after controlling for confounders. Associations were stronger when BPA was measured closer in time to total T4. BPA urinary concentrations were not associated with maternal free T4 or TSH, or with neonatal TSH. Conclusion: Maternal exposure to BPA was inversely associated with total T4 during pregnancy. Findings may have implications for fetal brain development.

Prenatal exposure to organochlorine pesticides and TSH status in newborns from Southern Spain

ObjectiveTo investigate the association between prenatal exposure to organochlorine pesticides (OCPs) and thyroid-stimulating hormone (TSH) levels in male newborns. MethodsExposure to 17 OCPs was analyzed in 220 placentas from a male birth cohort in Southern Spain, and TSH was measured in the umbilical cord blood. OCP concentrations were quantified by gas chromatography and mass spectrometry. Multivariate regression analysis was conducted to examine the association between pesticide exposure and neonatal TSH levels, adjusting for confounders. ResultsNewborn boys with higher exposure to endrin in placenta had higher odds of TSH cord blood levels ≥5mU/L (80th percentile) (OR=2.05; 95% CI=1.01, 4.18; p=0.05), whereas higher prenatal exposure to endosulfan-sulfate was associated with lower odds of TSH ≥5mU/L (OR=0.36; 95% CI=0.17, 0.77; p=0.008). A marginally significant negative association was found between TSH and hexachlorobenzene levels (β=−0.15; 95% CI=−0.31, 0.02; p=0.09), and exposure to p,p′-DDE showed a marginally-significant higher odds of TSH ≥5mU/L (OR=1.32; 95% CI=0.95, 1.83; p=0.09). No association was found between TSH and the remaining pesticides. ConclusionsEarly exposure to certain environmental chemicals with endocrine-disruption activity may interfere with neonatal thyroid hormone status; however, the pattern of interference is not yet clearly elucidated.

Neonatal Age and Point of CareTSH Testing in the Monitoring of Iodine Deficiency Disorders: Findings from Western Uganda

Iodine deficiency is a major public health problem throughout Africa. Although salt for human consumption is said to contain adequate amounts of iodine in Uganda, iodine intake may not be optimal. We undertook a field study to assess the adequacy of iodine nutrition in western Uganda using on-site measurement methods of neonatal thyroid stimulating hormone (TSH) levels as recommended by the World Health Organization (WHO) for monitoring the degree of iodine deficiency during pregnancy. The study design consisted of a prevalence study using the percentage of newborns between the ages of 3 and 7 days with TSH >5 mIU/L, measured with a point-of-care immunochromatographic TSH assay, as a surrogate marker of iodine deficiency. Five districts in western Uganda were selected for study on the basis of a past history of iodine deficiency. One thousand seventy-eight newborns from the five districts were sequentially enrolled in each separate district and tested between July 2007 and January 2008. The prevalence of TSH levels >5 mlU/L ranged from 20% to 32%. Neonates tested on or before the age of 3 days were more likely to have a TSH level >5 mlU/L than those tested beyond the age of three days (28.2% vs. 18.7%, p < 0.001). Assessing neonatal TSH levels in developing countries with a TSH assay method suitable for field use can be successfully used to screen for congenital hypothyroidism and to indirectly assess a population's iodine status. Based on the percentage of neonates with TSH values >5 mIU/L, presumptive iodine deficiency persists in western Uganda. This finding suggests that continued monitoring of iodine nutrition in the area surrounding the Rwenzori Mountains in Uganda and Congo is needed. Due to the progressive fall in the percent of TSH values >5 mIU/L from day three to day five of life, we conclude that TSH measurement earlier than day five of life in newborns at risk for iodine deficiency may be misleading. Guidelines for the use of neonatal TSH to monitor iodine nutrition should specify that TSH measurement take place no earlier than day five of life.

Perchlorate in Drinking Water During Pregnancy and Neonatal Thyroid Hormone Levels in California

To evaluate associations between maternal drinking water perchlorate exposure during pregnancy and newborn thyroid hormone levels. Elevation in thyroid stimulating hormone (TSH), which may reflect reduced thyroxin concentration, was assessed in 497,458 newborns in California in 1998. A total of 800 perchlorate water measurements were used to classify California communities as exposed (>5 μg/L) or unexposed. Results were stratified by age at TSH collection because of the normal postbirth TSH surge, and because water sources and perchlorate exposure can change soon after birth. In TSH samples collected within 24 hours of birth, the odds ratio for a TSH greater than 25 μU/mL in exposed communities was 1.53 (P < 0.0001). After 24 hours, the odds ratio for a TSH more than the 95th percentile was 1.27 (P < 0.0001). These findings suggest that perchlorate is associated with increased neonatal TSH levels.

Thyroid function screening of cord blood in infants born to mothers complicated with hypothyroidism during pregnancy

Objective To evaluate the clinical significance of thyroid stimulating hormone (TSH) and thyroid autoantibodies (anti-TGAb and anti-TPOAb) in cord blood of infants of mothers complicated with hypothyroidism and the influencing factors of neonatal thyroid function. Methods Clinical data of 67 singleton pregnant women complicated with hypothyroidism in Peking Union Medical College Hospital were analyzed retrospectively. Thyroid function and its autoantibody levels in maternal, cord blood and neonatal serum at 5-7 d after birth were compared. Umbilical TSH level and its affecting factors were also investigated. The results of TSH was expressed as median (25th-75th percentile). Results (1) Umbilical TSH levels were elevated in 9. 0% (6/67) of all infants born to mothers complicated with hypothyroidism. (2) No correlation was found in TSH levels between cord blood and venous blood in neonates 5-7 d after birth. Umbilical TSH levels were significantly higher in infants born vaginally than in those born abdominally [10. 20(6. 10-12. 80) mU/L vs 5. 86(4.02-7.74) mU/L,P=0.001]. Higher umbilical TSH levels were also detected in those complicated with fetal distress and preterm birth compared with those withoutere [fetal distress: (10. 36(6. 61-13. 37) mU/L and 6. 89(4. 18-9. 70) mU/L, P = 0. 046; preterm birth: 8. 90(7. 60-10. 33) mU/L and 6.84(4.17-9. 80) mU/L,P=0. 046,0. 049)]. (3) The anti-TGAb levels in cord blood were positively correlated with that in neonatal serum at 5-7 d after birth (r=0. 960, P = 0. 000), and the same was true for anti-TGPOAb levels (r= 0. 975, P = 0. 000). Maternal thyroid autoantibody levels (anti-TGAb and anti-TPOAb) had significant effect on umbilical antibody levels (P = 0. 003 and 0. 000, respectively), but not on the neonatal TSH levels (P>0. 05). Conclusions Umbilical TSH levels are affected by many delivery factors which may limit its prediction role on congenital hypothyroidism. However, there is an increased risk of elevated umbilical TSH, anti-TGAb and anti-TPOAb levels among these patients which may increase the risk of congenital hypothyroidism. Further follow up of these infants is warranted. Key words: Pregnancy complications; Hypothyroidism; Fetal blood; Thyrotropin

Prenatal exposure to organochlorine compounds and neonatal thyroid stimulating hormone levels

It has been suggested that prenatal exposure to some organochlorine compounds (OCs) may adversely affect thyroid function and may, therefore, impair neurodevelopment. The main aim of this study was to examine the relationship of cord serum levels of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane (4,4'-DDT), 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene (4,4'-DDE), β-hexachlorocyclohexane (β-HCH), hexachlorobenzene (HCB), four individual polychlorobiphenyl (PCB) congeners (118, 138, 153, and 180), and their sum, with neonatal thyroid stimulating hormone (TSH) levels in blood samples in a mother-infant cohort in Valencia, Spain. This study included 453 infants born between 2004 and 2006. We measured OC concentrations in umbilical cord serum and TSH in blood of newborns shortly after birth. Associations between neonatal TSH levels and prenatal OC exposure adjusted for covariates were assessed using multivariate linear regression analyses. Neonatal TSH levels tended to be higher in newborns with β-HCH levels in umbilical cord above 90th percentile (104 ng/g lipid) than in those with levels below the median (34 ng/g lipid), with an adjusted increment in neonatal TSH levels of 21% (95% confidence interval=-3, 51; P=0.09). No statistically significant association was found between the remaining OCs and TSH at birth. Prenatal exposure to β-HCH may affect neonatal thyroid hormone status and its function in neurological development.