Reference intervals for thyrotropin and thyroid hormones and ultrasonographic thyroid volume during the neonatal period

High frequency of transient congenital hypothyroidism among infants referred for suspected congenital hypothyroidism from the Turkish National screening program: thyroxine dose may guide the prediction of transients

PURPOSE

We aimed to determine the frequency of transient congenital hypothyroidism (TCH) in 17 participating centers in Türkiye, evaluate the etiological distribution in permanent congenital hypothyroidism (PCH) cases, and investigate the role of laboratory and clinical findings in predicting TCH.

METHODS

This retrospective observational multicenter study included patients from 17 pediatric endocrinology centers identified by "National Newborn Screening Program" (NNSP) who were born in 2015 and followed for 6 years. Demographic, clinical, and laboratory information of the cases were compiled through the database http://cedd.saglik-network.org (CEDD-NET).

RESULTS

Of the 239 cases initially treated for CH, 128 (53.6%) were determined as transient in whom a trial of levothyroxine (LT4) withdrawal was performed at a median age of 36 (34-38) months. Among the patients with PCH (n = 111), thyroid dysgenesis was diagnosed in 39.6% (n = 44). The predictive factors for TCH were: LT4 dose at the withdrawal of treatment, and initial newborn blood screening (NBS)-TSH level. Based on the receiver operating characteristic (ROC) curve analysis to predict optimal cut-offs for TCH predictors, LT4 dose < 2.0 µg/kg/day at treatment discontinuation was predictive for TCH and was associated with 94.5% specificity and 55.7% sensitivity, with an area under the curve (AUC) of 0.802. The initial NBS-TSH level value < 45 µIU/mL was predictive for TCH with 93.1% specificity and 45.5% sensitivity, with an AUC of 0.641. In patients with eutopic thyroid gland only LT4 dose < 1.1 µg/kg/day at withdrawal time was predictive for TCH with 84.7% sensitivity and 40.4% specificity, with an AUC of 0.750.

CONCLUSION

According to our national follow-up data, the frequency of TCH was 53.6%. We determined the LT4 dose < 2.0 µg/kg/day at discontinuation of treatment and the initial NBS-TSH level < 45 µIU/mL as the best cut-off limits to predict TCH.

Free thyroxine measurement in clinical practice: how to optimize indications, analytical procedures, and interpretation criteria while waiting for global standardization

Thyroid dysfunctions are among the most common endocrine disorders and accurate biochemical testing is needed to confirm or rule out a diagnosis. Notably, true hyperthyroidism and hypothyroidism in the setting of a normal thyroid-stimulating hormone level are highly unlikely, making the assessment of free thyroxine (FT4) inappropriate in most new cases. However, FT4 measurement is integral in both the diagnosis and management of relevant central dysfunctions (central hypothyroidism and central hyperthyroidism) as well as for monitoring therapy in hyperthyroid patients treated with anti-thyroid drugs or radioiodine. In such settings, accurate FT4 quantification is required. Global standardization will improve the comparability of the results across laboratories and allow the development of common clinical decision limits in evidence-based guidelines. The International Federation of Clinical Chemistry and Laboratory Medicine Committee for Standardization of Thyroid Function Tests has undertaken FT4 immunoassay method comparison and recalibration studies and developed a reference measurement procedure that is currently being validated. However, technical and implementation challenges, including the establishment of different clinical decision limits for distinct patient groups, still remain. Accordingly, different assays and reference values cannot be interchanged. Two-way communication between the laboratory and clinical specialists is pivotal to properly select a reliable FT4 assay, establish reference intervals, investigate discordant results, and monitor the analytical and clinical performance of the method over time.

The longitudinal effect of oxcarbazepine on thyroid function in children and adolescents with epilepsy

OBJECTIVE

Thyroid hormone abnormalities have been linked to antiseizure medications (ASMs). Oxcarbazepine is considered safer than carbamazepine because it induces the hepatic cytochrome P450 metabolic enzymes less than the carbamazepine does. However, limited data exist for the influence of oxcarbazepine on thyroid function in children and adolescents. The objective of this study was to determine the effect of oxcarbazepine on thyroid function in these patients.

METHODS

A total of 162 pediatric patients with epilepsy who started oxcarbazepine for the first time between April 2003 and May 2020 were enrolled. The longitudinal effects of oxcarbazepine for thyroid functions were confirmed using general estimating equations.

RESULTS

Serum triiodothyronine (T3), thyroxine (T4), and free thyroxine (fT4) levels decreased significantly during 5 years of follow-up (all p's < .001). In particular, T3 and fT4 levels were reduced steeply in the first 2 years of oxcarbazepine treatment. There was no significant change in thyroid-stimulating hormone during oxcarbazepine treatment.

SIGNIFICANCE

Serum T3, T4, and fT4 levels decreased significantly during oxcarbazepine use, and this change was maintained during the treatment period. In patients receiving oxcarbazepine, it is recommended that periodic thyroid function testing should be performed, especially within the first 2 years after starting this ASM. Our results indicate that oxcarbazepine-induced hypothyroidism does not appear to be accompanied by a significant increase in TSH, and consequently might be missed if TSH alone is monitored as a measure of thyroid dysfunction.

Screening of 23 candidate genes by next-generation sequencing of patients with permanent congenital hypothyroidism: novel variants in TG, TSHR, DUOX2, FOXE1, and SLC26A7

PURPOSE

To date, many genes have been associated with congenital hypothyroidism (CH). Our aim was to identify the mutational spectrum of 23 causative genes in Turkish patients with permanent CH, including thyroid dysgenesis (TD) and dyshormonogenesis (TDH) cases.

METHODS

A total of 134 patients with permanent CH (130 primary, 4 central) were included. To identify the genetic etiology, we screened 23 candidate genes associated with CH by next-generation sequencing. For confirmation and to detect the status of the specific familial variant in relatives, Sanger sequencing was also performed.

RESULTS

Possible pathogenic variants were found in 5.2% of patients with TD and in 64.0% of the patients with normal-sized thyroid or goiter. In all patients, variants were most frequently found in TSHR, followed by TPO and TG. The same homozygous TSHB variant (c.162 + 5G > A) was identified in four patients with central CH. In addition, we detected novel variants in the TSHR, TG, SLC26A7, FOXE1, and DUOX2.

CONCLUSION

Genetic causes were determined in the majority of CH patients with TDH, however, despite advances in genetics, we were unable to identify the genetic etiology of most CH patients with TD, suggesting the effect of unknown genes or environmental factors. The previous studies and our findings suggest that TSHR and TPO mutations is the main genetic defect of CH in the Turkish population.

Prevalence of transient congenital hypothyroidism among neonates

OBJECTIVE

Persistence of low levels of thyroid hormone from the time of birth is one of the significant causes of the mental retardation. The aim of this study was to determine the prevalence of transient congenital hypothyroidism among neonates in (XXX).

METHODS

This cross-sectional study, neonates aged 3-5 days who were referred to our center for checkup were screened for thyroid stimulating hormone. Those with TSH < 5mIU/l were, infants were subjected to retesting after one week for TSH and T4 levels. A questionnaire consisting of test results, demographic characteristics, place of sampling, gender, need for re-sampling after the second week for TSH level, birth weight, type of hypothyroidism and prematurity was filled for all the neonates.

RESULTS

Of 3600 neonates screened, 126 were presented with had TSH above 5 mIU/l, of which 7 had high TSH and low T4 and were diagnosed with transient hypothyroidism (5.3%). The mean weight of the neonates with hypothyroidism of significantly lower, p = 0.001. However, the type of delivery was not associated with the prevalence of hypothyroidism, p = 0.999. The relationship between maternal hypothyroidism, preterm birth and intake of antithyroid drugs and transient hypothyroidism was statistically significant, p < 0.001, respectively.

CONCLUSIONS

The incidence of congenital hypothyroidism was 1 in 514 births and was significantly associated with preterm birth, mean weight, maternal hypothyroidism and intake of antithyroid drugs. Routine screening in high prevalence regions are therefore importance, considering the associated factors.

Newborn Screening for Congenital Hypothyroidism: the Benefit of Using Differential TSH Cutoffs in a 2-Screen Program

CONTEXT

Analysis of a 2-screen program for congenital hypothyroidism (CH) was performed using differential dried-blood spot thyrotropin (bTSH) cutoffs of 10 mU/L at first screening (all infants) and 5 mU/L at second screening (selected infants).

OBJECTIVES

This work aimed to characterize CH infants identified by the second screening and compare infants with bTSH of 5.0 to 9.9 and 10 mU/L or greater on second screening.

DESIGN AND PATIENTS

Maternal and neonatal clinical features were retrospectively analyzed for 119 CH babies detected on the second screen in the Lombardy region of Italy, 2007 to 2014.

RESULTS

Fifty-two (43.7%) of the 119 CH neonates showed bTSH values ranging from 5.0 to 9.9 mU/L at the second screening (low bTSH group) and 67 (56.3%) bTSH of 10.0 mU/L or greater (high bTSH group). The frequency of thyroid dysgenesis and eutopic gland was similar in both groups, as was the frequency of permanent and transient CH. Moreover, a high frequency of extrathyroidal malformations was found in both groups. The percentage of preterm infants (57.7% vs 23.9%, P < .001) and infants admitted to the neonatal intensive care unit (50.0% vs 17.9%, P < .001) was significantly higher in the low vs the high bTSH group. In addition, maternal treatment with glucocorticoids in pregnancy was significantly more frequent in the low bTSH group than in the high bTSH group (11.5% vs 1.5%, P = .042), as well as maternal hypothyroidism and/or goiter (26.9% vs 10.4%, P = .036).

CONCLUSIONS

This study has demonstrated that a lower TSH cutoff at the second screening can detect additional cases of CH and that a second bTSH cutoff of 5.0 mU/L is appropriate for identifying preterm newborns and babies with associated risk factors.

Reference intervals for thyroid-stimulating hormone (TSH) and free thyroxine (FT4) in infants' day 14-30 of life and a comparison with other studies

Objectives Established reference intervals of thyroid function in neonates are important; however, studies often consist of a small sample size or lack of clinical information. We aim to define reference intervals for thyroid-stimulating hormone (TSH) and free thyroxine (FT4) for infants aged 14-30 days. We also reviewed follow-up TSH for infants with initial values 10-20 mIU/L. Methods Venous TSH and FT4 of term babies aged 14-30 days with breast milk jaundice that had thyroid function test performed as part of a prolonged jaundice workout from September 2016 to March 2017 were analyzed. Electronic medical records were reviewed to ensure only well babies with no pathological causes of jaundice or conditions that may affect thyroid function were included. TSH and FT4 were analyzed using immunoassay analyzer Dxl 800, Beckman Coulter. Results There were no correlations between FT4 and TSH with gender, birth weight and ethnicity. Correlation coefficient between FT4 and total bilirubin was weak at 0.138 (p=0.001). No association was found between TSH and bilirubin levels. Mean FT4 was higher in the younger age group day 14-21 (p<0.01). There was no significant difference in TSH values between the age groups. Infants with mildly elevated TSH 10-20 mIU/L had normalized values on follow-up (mean, 11.41 vs. 4.42 mIU/L; p<0.01; 95%CI, 5.88-8.09). The following reference intervals (2.5-97.5th percentile) were derived: FT4 day 14-21 (n=513): 11.59-21.00 pmoL/L; FT4 day 22-30 (n=66): 10.14-19.60 pmoL/L; TSH day 14-30 (n=579): 1.90-10.34 mIU/L. Comparison between studies showed variations of reference intervals with different manufacturer assays, age and methodology. Conclusions Our reference intervals would be useful in the clinical setting. Infants with mildly elevated TSH could be monitored first instead of immediate treatment.

Reducing unnecessary neonatal testing in infants of mothers with thyroid disease

AIM

To examine the numbers of asymptomatic infants <8 weeks who had appropriate thyroid function tests (TFTs) in addition to the newborn screening test, because of maternal thyroid disease, before and after the implementation of an updated institutional guideline and staff education.

METHODS

A medical record audit of infants <8 weeks born at a metropolitan teaching hospital, who had TFTs between 1 July 2017 and 31 October 2017 was performed as part of a quality improvement project. Records were reviewed to determine the indication for testing and whether this complied with the current 2011 institutional guideline. A multidisciplinary staff education package was developed to coincide with the publication of an updated guideline in August 2018. Staff education and resources were provided throughout July 2018. A post-intervention audit was repeated between 1 August 2018 and 1 December 2018, assessing compliance with the 2018 guideline.

RESULTS

In the baseline period, 40 of 457 infants born had TFTs performed, of which 26 of 40 (65%) were for maternal thyroid disease. Of these 10 of 26 (38%) met the 2011 criteria for testing; 1 of 26 (4%) met the updated 2018 criteria. In the post-intervention period, 14 of 412 infants born had TFTs of which 5 of 14 (36%) were tested due to maternal thyroid disease and all were compliant with the new guideline.

CONCLUSIONS

Baseline audit revealed unnecessary neonatal thyroid function testing of healthy babies. Implementation of an updated guideline and a brief, targeted education package successfully increased awareness of the updated recommendations, reduced unnecessary testing and led to improved practice.

Age-Specific Reference Intervals for Plasma Free Thyroxine and Thyrotropin in Term Neonates During the First Two Weeks of Life

Background: Congenital hypothyroidism (CH) is a common and preventable cause of mental retardation, which is detected in many neonatal screening programs. Upon suspicion of CH, plasma free thyroxine (fT4) and thyrotropin (TSH) concentrations are measured. CH can be of thyroidal or central origin (CH-T and CH-C, respectively). While CH-T diagnosis is based on an elevated TSH with a low fT4, CH-C diagnosis is based on a low fT4 without a clearly elevated TSH. Currently, reliable neonatal reference intervals (RIs) for plasma fT4 and TSH are lacking. Age-specific RIs would greatly improve the diagnostic process for CH, especially for CH-C. Our aim was to establish neonatal RIs for plasma fT4 and TSH in term neonates at day 3-7 (t = 1) and day 13-15 (t = 2). The study was particularly designed to provide a reliable fT4 lower limit of the RI to facilitate the diagnosis of CH-C. In the Netherlands, neonates are screened at day 3-7 of life. After a screening result suggestive for CH-C, pediatric consultation takes place on average at day 14. Thus, the time points were chosen accordingly. Methods: Venous blood was collected from 120 healthy neonates at each time point (94 participants provided blood samples at two time points; 52 participants provided a sample at t = 1 or t = 2). fT4 and TSH were measured using an immunoassay (Cobas; Roche Diagnostics). RIs were calculated using the 95% confidence interval for normally distributed data and the nonparametric percentile method if data were not normally distributed. Results: From 146 participants (49% female), ≥1 measurement was available. Ninety-five percent RIs for fT4 were 20.5-37.1 pmol/L (day 3-7) and 15.3-26.5 pmol/L (day 13-15). Ninety-five percent RIs for TSH were 1.0-8.4 mU/L (day 3-7) and 1.4-8.6 mU/L (day 13-15). Conclusions: Our results indicate an fT4 lower limit of the RI of 20.5 pmol/L at day 3-7 and 15.3 pmol/L at day 13-15. These lower limits are considerably higher than this assay's lower limit of the adult RI for fT4. In case CH is suspected, we recommend measuring fT4 and TSH using an assay with an established neonatal RI, taking into account the child's age in days.

Divergent Patterns of Thyrotropin and Other Thyroidal Parameters in Relationship with the Sex of Healthy Neonates and Infants Less than Two Years Old: A Longitudinal Study

Background: A longitudinal study was conducted in full-term healthy infants who were born between 2015 and 2017 in Athens, Greece, to elucidate the evolution of thyrotropin (TSH) and other thyroidal parameters according to sex, from their day of birth until two years old. Other thyroidal parameters that were taken into account include antithyroid peroxidase antibody (TPO-Ab) and antithyroglobulin antibody (TG-Ab), total triiodothyronine (T3), and free triiodothyronine (fT3), along with total thyroxine (T4) and free thyroxine (fT4). Methods: Blood samples were taken at 5-day intervals from the day of birth until the 31st day of life, and then every 5th month until 2 years of age. All thyroid parameters were measured by electrochemiluminescence immunoassays. The study took place at the Iaso General, Maternity and Gynecological Clinic in Athens, Greece. Results: The sample consisted of 2916 full-term healthy neonates/infants: 1507 (51.7%) boys and 1409 (48.3%) girls. There were no significant differences in TSH levels between boys and girls in all time periods from birth up to 2 years except between 11 and 15 months of age (p = 0.038). Mean TSH levels for boys exhibited much more fluctuation and variability than for girls. In boys we found a significant association between TSH levels and fT4 (p < 0.001), while we found a significant association between TSH levels and T3 in girls (p = 0.045). Furthermore, we found that mean TPO-Ab and TG-Ab levels for boys exhibited larger variability than those for girls. Conclusions: In this study, we were able to plot the development of TSH and other thyroidal parameters by sex from birth up to two years of age. In terms of clinical practice, our findings suggest the need for a re-evaluation of the reference ranges of the studied parameters according to sex, especially in the first months of life and until the first year. Furthermore, our results suggest new optimal ranges for thyroid hormone replacement for that specific period.

Neonatal effects of thyroid diseases in pregnancy and approach to the infant with increased TSH: Turkish Neonatal and Pediatric Endocrinology and Diabetes Societies consensus report

Thyroid functions in the fetus and newborn carry importance in terms of the baby's health and development of the central nervous system. Maternaliodine deficiency, exposure to iodine, thyroid diseases (Hashimoto thyroiditis, Graves') and drugs used by the mother affect thyroid functions in the fetus. Reflections of these effects are observed immediately after delivery. Investigation of the mother in terms of thyroid diseases during pregnancy, recognition and appropriate assessment of the required conditions, screening of all newborns in the first days of life in terms of congenital hypothyroidism, timely and appropriate evaluation of the screening results, early diagnosis and appropriate treatment of cases of congenital hypothyroidism, assessment and management of cases of transient thyroid hormone disorders and close monitoring of the thyroid functions and development of patients in whom treatment has been initiated with a diagnosis of hypothyroidism are crucial in terms of developmental outcomes of the babies who have thyroid function disorders or hypothyroidism. This guideline was written with the objective of guiding pediatricians, neonatologists and pediatric endocrinologists in the issue of assessment, diagnosis and management of thyroid function disorders and thyroid diseases concerning the fetus and baby during gestation and neonatal period.

Normative Data of Thyroid Gland Volume in South Indian Neonates and Infants

OBJECTIVE

To establish normative ultrasound data for thyroid gland volume in South Indian neonates and infants and compare with abnormal sonological features of thyroid in congenital hypothyroidism (CH) to explore thyroid ultrasound utility as a supportive screening tool to newborn screening programs for early detection of CH.

METHODS

In view of impact of geo ethnic factors, varying growth velocities and body mass indices of human population worldwide, specific regional, age and gender related reference data for thyroid gland size and volume are vital. This study was an offshoot of ICMR pilot New Born Screening (NBS) project for CH. Formula used for thyroid volume estimation was ellipsoidal formula D1 x D2 x D3 × 0.523. It was a prospective observational study. The neonates who screened negative for Thyroid Stimulating Hormone (TSH) with repeat normal serum TSH and free thyroxine were selected. One hundred fifty seven infants were enrolled which included 99 boys and 58 girls. The study population included children in age groups from 3 d to 1 y six months.

RESULTS

Data analysis was done by descriptive method and unpaired t test. Mean thyroid volume was 0.26 ml with 0.27 ml in boys and 0.24 ml in girls. Statistically significant "p value" was noted in single lobe measurements among boys and girls.

CONCLUSIONS

Thyroid gland volume normative data play a key role in evaluation of thyroid sonological abnormalities in CH and there is effective utility of ultrasound as a supportive diagnostic and prognostic screening tool for early detection of CH.

Newborn Screening Guidelines for Congenital Hypothyroidism in India: Recommendations of the Indian Society for Pediatric and Adolescent Endocrinology (ISPAE) - Part I: Screening and Confirmation of Diagnosis

The Indian Society for Pediatric and Adolescent Endocrinology has formulated locally relevant Clinical Practice Guidelines for newborn screening, diagnosis and management of primary congenital hypothyroidism (CH).

RECOMMENDATIONS

Screening should be done for every newborn using cord blood, or postnatal blood, ideally at 48 to 72 h of age. On this screen sample, neonates with TSH > 20 mIU/L serum units (or >34 mIU/L for samples taken between 24 to 48 h of age) should be recalled for confirmation. For screen TSH > 40 mIU/L, immediate confirmatory venous T4/FT4 and TSH, and for milder elevation of screen TSH, a second screening TSH at 7 to 10 d of age, should be taken. Preterm and low birth weight infants should undergo screening at 48-72 h postnatal age. Sick babies should be screened at least by 7 d of age. Venous confirmatory TSH >20 mIU/L before age 2 wk and >10 mIU/L after age 2 wk, with low T4 (<10 μg/dL) or FT4 (<1.17 ng/dL) indicate primary CH and treatment initiation. Imaging is recommended by radionuclide scintigraphy and ultrasonography after CH is biochemically confirmed but treatment should not be delayed till scans are performed. Levothyroxine is commenced at 10 to 15 μg/kg in the neonatal period. Serum T4/FT4 is measured at 2 wk and TSH and T4/FT4 at 1 mo, then 2 monthly till 6 mo, 3 monthly from 6 mo-3 y and every 3-6 mo thereafter. Babies with the possibility of transient congenital hypothyroidism should be re-evaluated at age 3 y, to assess the need for lifelong therapy.

Maternal urinary phthalate metabolites during pregnancy and thyroid hormone concentrations in maternal and cord sera: The HOME Study

BACKGROUND

Phthalates, endocrine-disrupting chemicals that are commonly found in consumer products, may adversely affect thyroid hormones, but findings from prior epidemiologic studies are inconsistent.

OBJECTIVES

In a prospective cohort study, we investigated whether maternal urinary phthalate metabolite concentrations and phthalate mixtures measured during pregnancy were associated with thyroid hormones among pregnant women and newborns.

METHODS

We measured nine phthalate metabolites [monoethyl phthalate (MEP), mono-n-butyl phthalate, mono-isobutyl phthalate, monobenzyl phthalate (MBzP), and four monoesthers of di(2-ethylhexyl) phthalate] in urine collected at approximately 16 and 26 weeks' gestation among women in the Health Outcomes and Measures of the Environment Study (2003-2006, Cincinnati, Ohio). Thyroid stimulating hormone (TSH) and free and total thyroxine and triiodothyronine were measured in maternal serum at 16 weeks' gestation (n = 202) and cord serum at delivery (n = 276). We used multivariable linear regression to assess associations between individual urinary phthalate metabolites and concentrations of maternal or cord serum thyroid hormones. We used weighted quantile sum regression (WQS) to create a phthalate index describing combined concentrations of phthalate metabolites and to investigate associations of the phthalate index with individual thyroid hormones.

RESULTS

With each 10-fold increase in 16-week maternal urinary MEP, maternal serum total thyroxine (TT₄) decreased by 0.52 μg/dL (95% CI: -1.01, -0.03). For each 10-fold increase in average (16- and 26-week) maternal urinary MBzP, cord serum TSH decreased by 19% (95% CI: -33.1, -1.9). Among mothers, the phthalate index was inversely associated with maternal serum TT₄ (WQS beta = -0.60; 95% CI: -1.01, -0.18). Among newborns, the phthalate index was inversely associated with both cord serum TSH (WQS beta = -0.11; 95% CI: -0.20, -0.03) and TT₄ (WQS beta = -0.53; 95% CI: -0.90, -0.16).

CONCLUSION

Our results suggest that co-exposure to multiple phthalates was inversely associated with certain thyroid hormones (TT₄ in pregnant women and newborns, and TSH in newborns) in this birth cohort. These findings highlight the need to study chemical mixtures in environmental epidemiology.

Does Ventriculoperitoneal Shunting Improve Thyroid Hormone Levels in Hydrocephalic Newborns?

OBJECTIVE/AIM

The aim of this report was to investigate the effect of ventriculoperitoneal shunt insertion for the treatment of hydrocephalus on thyroid hormones in the first 3 months of life.

METHODS

Thyroid-stimulating hormone (TSH), free T3 (fT3), and free T4 (fT4) levels were compared at 7 days (preoperatively) and at 30 and 90 days (postoperatively) after birth between 25 ventriculoperitoneal shunt-inserted hydrocephalic newborns and 20 healthy newborns.

RESULTS

The TSH level at 7 days was higher in the hydrocephalic patient group (6.33 µIU) compared to the control group (3.76 µIU). This value was significantly decreased at 90 days in the ventriculoperitoneal shunt-inserted newborns (2.35 µIU) compared to the control group (3.33 µIU; p < 0.05). There were no significant differences between time points for fT4 and fT3 values in the patient group or for TSH, fT4, and fT3 values in the control group.

CONCLUSION

We propose that a ventriculoperitoneal shunt inserted in the early period of life may have beneficial effects on thyroid hormones.

Establishment of reference intervals of thyroid function tests from cord blood of neonates in two selected hospitals, Addis Ababa, Ethiopia

BACKGROUND

Reference intervals are affected by different factors such as lifestyle, ethnicity, age/developmental stage, gender, nutrition and other environmental factors (Clin Biochem Rev: 29,2008). Therefore, it is obvious that it should be established for every population in different regions even within a country. Then the aim of this study is to establish population specific reference intervals of thyroid stimulating hormone, free thyroxine and free triidothyronine levels of cord blood.

RESULTS

One hundred twenty three cord blood samples collected from the umbilical cord of newborns were analyzed for thyroid stimulating hormone, free thyroxine and free triidothyronine values. The birth weights ranged between 2500 and 4700 g with mean (SD) value of 3241.46 (459.495) gram. Their gestational age ranged between 37 and 44 weeks with an average of 39.74 weeks. The 2.5(th) and 97.5(th) percentiles of values were found to be 3.48 mIU/L and 27.57 mIU/L for thyroid stimulating hormone, 0.89 ng/dl and 1.53 ng/dl for free thyroxine and 1.19 pg/ml and 2.51 pg/ml for free triidothyronine respectively.

CONCLUSION

In the present study the reference intervals of thyroid stimulating hormone, free thyroxine and free triidothyronine were established and based on the results obtained, were 3.48-27.56 mIU/L for thyroid stimulating hormone, 0.89-1.53 ng/dl for free thyroxine and 1.19-2.51 pg/ml for free triidothyronine. It has been concluded that the result can provide us with an important baseline to establish population specific reference intervals for our country using large scale studies.

How well does the capillary thyroid-stimulating hormone test for newborn thyroid screening predict the venous free thyroxine level?

OBJECTIVES

To determine, in newborn infants referred with elevated capillary thyroid-stimulating hormone (TSH), a threshold below which a frankly subnormal venous free thyroxine (fT4) level of <10 pmol/L is unlikely, so that treatment with levo-thyroxine (L-T4) might be deferred until venous thyroid function tests (TFTs) become available.

SUBJECTS AND METHODS

All infants referred in Scotland since 1979 with capillary TSH elevation were studied, with particular focus on infants screened using the AutoDELFIA assay between 2002 and 2013.

RESULTS

Of the 321 infants referred with capillary TSH elevation using AutoDELFIA, 35 were excluded (fT4/TSH unavailable (12), venous sample either preceding or >10 days after capillary sampling (13, 10)), leaving 286 eligible for analysis (208 definite/probable hypothyroidism, 61 transient TSH elevation, 17 of uncertain thyroid status). Capillary TSH and venous T4 were strongly correlated (Spearman's rank correlation coefficient -0.707355). The optimal capillary TSH threshold for predicting a venous fT4 of <10 pmol/L was found to be >40 mU/L (90.3% sensitivity and 65.9% specificity compared with 90.25% and 59.1% for >35 mU/L and 88.3% and 68.2% for >45 mU/L). 93 infants (32.5%) had capillary TSH ≤40 mU/L at referral of whom 15 (9.7%) had venous fT4 <10 pmol/L, comprising seven with true congenital hypothyroidism, five with transient TSH elevation and three with uncertain status, two of whom died.

CONCLUSION

For infants in whom capillary TSH is ≤40 mU/L, it is reasonable to defer L-T4 treatment until venous TFT results are known provided that the latter become available quickly.

Sonographic evaluation of the thyroid size in neonates

PURPOSE

To validate the use of the ratio between the total transverse diameters of the thyroid lobes (Th) and the width of the trachea (Tr)-the Th:Tr or Yasumoto ratio-as a sonographic method for estimating thyroid size, and to determine reference values for this ratio and for thyroid volume in neonates.

METHODS

In this cross-sectional study, we evaluated thyroid size according to the Yasumoto ratio and the thyroid volume calculated with the ellipsoid formula in 125 healthy, euthyroid, iodine-sufficient, full-term neonates.

RESULTS

The mean thyroid gland volume was 1.00 ml (95% confidence interval, 0.95-1.03 ml), and the mean Yasumoto ratio was 2.29 (95% confidence interval, 2.21-2.31). The lower- and upper-limit results falling within 2 SDs of the mean were 0.45 ml and 1.53 ml for the volume and 1.71 and 2.87 for the ratio.

CONCLUSIONS

In full-term, euthyroid, iodine-sufficient neonates, the normal reference interval for thyroid volume measured on sonography was 0.45-1.53 ml and that for the Yasumoto ratio was 1.71-2.87. A ratio of 1.7 may be applied as the cutoff value for sonographic diagnosis of thyroid dysgenesis in full-term neonates with congenital hypothyroidism. © 2014 Wiley Periodicals, Inc. J Clin Ultrasound 43:224-229, 2015.

Nomogram-based evaluation of thyroid function in appropriate-for-gestational-age neonates in intensive care unit

OBJECTIVE

The objective of this study was to help neonatologists to interpret the thyroid hormone results accurately, and also to provide reference ranges and/or nomograms of FT4 (free thyroxine) and thyrotropin against gestational age at postnatal 1 week and 1 month in order to assess thyroid function in AGA (appropriate for gestational age) neonates in intensive care unit.

STUDY DESIGN

This is a retrospective study. We included a total number of 515 AGA neonates between 24 and 42 weeks of gestation. Routine results of serum FT4 and TSH that had been analyzed with an immunoassay were collected from existing laboratory data. Least square regression analyses were used to estimate both the mean and the s.d. curves as polynomial functions of gestational age.

RESULT

Free T4 levels were correlated with gestational age both at postnatal 1 week (r=0.39, P<0.001) and 1 month (r=0.26, P<0.001). Serum TSH levels at postnatal 1 week and 1 month did not show any correlation with gestational age. Scatterplots of FT4 levels against gestational age at 1 week and 1 month, showing the predicted 2.5th, 50th and 97.5th percentiles and central 95% reference ranges for TSH were provided.

CONCLUSION

Gestational age-specific nomograms for FT4 and reference ranges for TSH at postnatal 1 week and 1 month in AGA neonates have been developed. This can help neonatologists to interpret the thyroid hormone results accurately. Further studies providing reference ranges/nomograms for thyroid function in small-for-gestational-age neonates are needed.

European Society for Paediatric Endocrinology consensus guidelines on screening, diagnosis, and management of congenital hypothyroidism

OBJECTIVE

The aim was to formulate practice guidelines for the diagnosis and management of congenital hypothyroidism (CH).

EVIDENCE

A systematic literature search was conducted to identify key articles relating to the screening, diagnosis, and management of CH. The evidence-based guidelines were developed with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system, describing both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion.

CONSENSUS PROCESS

Thirty-two participants drawn from the European Society for Paediatric Endocrinology and five other major scientific societies in the field of pediatric endocrinology were allocated to working groups with assigned topics and specific questions. Each group searched the literature, evaluated the evidence, and developed a draft document. These papers were debated and finalized by each group before presentation to the full assembly for further discussion and agreement.

RECOMMENDATIONS

The recommendations include: worldwide neonatal screening, approaches to assess the cause (including genotyping) and the severity of the disorder, the immediate initiation of appropriate L-T4 supplementation and frequent monitoring to ensure dose adjustments to keep thyroid hormone levels in the target ranges, a trial of treatment in patients suspected of transient CH, regular assessments of developmental and neurosensory functions, consulting health professionals as appropriate, and education about CH. The harmonization of diagnosis, management, and routine health surveillance would not only optimize patient outcomes, but should also facilitate epidemiological studies of the disorder. Individuals with CH require monitoring throughout their lives, particularly during early childhood and pregnancy.

Thyroid function and dysfunction in term and premature equine neonates

Background

This study was performed to compare thyroid function of premature foals to term foals.

Hypothesis

Premature foals are more markedly hypothyroxinemic than expected for their severity of illness alone.

Animals

Twenty clinically normal term foals; 28 sick, hospitalized term foals; 24 sick, hospitalized premature foals.

Methods

Thyroid hormones (TH) and thyrotropin (TSH) were measured, both at rest and in response to thyrotropin‐releasing hormone (TRH), in the 3 groups of foals. Clinical and clinicopathologic data were recorded.

Results

Normal foals had high TH at birth, which decreased over the first month into the normal reference range for adult horses. TSH was within the normal adult reference range soon after birth, and did not change over time. At 24–36 hours of age, triiodothyronine (T3) was significantly lower in both premature and term hospitalized foals compared to normal foals; premature foals were not different from term hospitalized foals. Thyroxine (T4) was not different between normal and term hospitalized foals, but was significantly lower than in premature foals of both of these groups. TSH was not different among the 3 groups. TRH stimulation tests identified significant differences in T4 among all 3 groups of foals, whereas T3 was similar in premature and term hospitalized foals and different from normal foals. TSH response to TRH was significantly higher in premature foals compared to normal foals.

Conclusions and Clinical Importance

The hypothalamic‐pituitary‐thyroid axis is different in foals compared to adult horses. Sick foals exhibit nonthyroidal illness syndrome. Premature foals are more markedly hypothyroxinemic than can be accounted for by their severity of illness alone.

European Society for Paediatric Endocrinology consensus guidelines on screening, diagnosis, and management of congenital hypothyroidism

OBJECTIVE

The aim was to formulate practice guidelines for the diagnosis and management of congenital hypothyroidism (CH).

EVIDENCE

A systematic literature search was conducted to identify key articles relating to the screening, diagnosis, and management of CH. The evidence-based guidelines were developed with the Grading of Recommendations, Assessment, Development and Evaluation (GRADE) system, describing both the strength of recommendations and the quality of evidence. In the absence of sufficient evidence, conclusions were based on expert opinion.

CONSENSUS PROCESS

Thirty-two participants drawn from the European Society for Paediatric Endocrinology and five other major scientific societies in the field of pediatric endocrinology were allocated to working groups with assigned topics and specific questions. Each group searched the literature, evaluated the evidence, and developed a draft document. These papers were debated and finalized by each group before presentation to the full assembly for further discussion and agreement.

RECOMMENDATIONS

The recommendations include: worldwide neonatal screening, approaches to assess the cause (including genotyping) and the severity of the disorder, the immediate initiation of appropriate L-T4 supplementation and frequent monitoring to ensure dose adjustments to keep thyroid hormone levels in the target ranges, a trial of treatment in patients suspected of transient CH, regular assessments of developmental and neurosensory functions, consulting health professionals as appropriate, and education about CH. The harmonization of diagnosis, management, and routine health surveillance would not only optimize patient outcomes, but should also facilitate epidemiological studies of the disorder. Individuals with CH require monitoring throughout their lives, particularly during early childhood and pregnancy.

Serum thyroid stimulating hormone, total and free T4 during the neonatal period: Establishing regional reference intervals

CONTEXT

Congenital hypothyroidism (CH), the most common etiology of preventable mental retardation in children, is estimated to be more prevalent among Asian population.

AIMS

Since thyroid function tests (TFTs) varied among different ages and geographical regions, in this study, the neonatal thyroid reference intervals in a healthy neonatal population is determined for the first time in Iran.

SETTINGS AND DESIGN

A cross-sectional study performed on 246 healthy term newborns aged between 2 days and 1 month.

MATERIALS AND METHODS

Blood samples were obtained by venipuncture from all subjects. The median, 2.5(th), 5(th), 95(th), and 97.5(th) percentile of serum thyroid-stimulating hormone (TSH), as well as the total and free T4 were assessed among different age groups.

STATISTICAL ANALYSIS USED

Predictive Analytics Software (PASW Statistics 18) was used for the analysis.

RESULTS

Serum TSH, total and free T4 concentration peaked in 5(th) to 7(th) days of life, continued over 2 weeks, then decreased and started reaching to adult reference range. A significant negative correlation between age and serum concentration of TSH (P = 0.02), total T4 (P = 0.01) and free T4 (P = 0.01) was found.

CONCLUSION

This study yielded fairly different values for TFTs compared compared values found in other countries and also different from values reported for laboratory kits we used. These differences were assumed to be due to variations in ethnicity, age, and laboratory methods used. Due to the lack of international standardization, conducting multicenter studies helps in making a more precise evaluation of thyroid status in neonates.