Incidence Of Congenital Hypothyroidism Research Articles

The Relationship Between Maternal Hypothyroidism and the Incidence of Congenital Hypothyroidism in Infants: A Cross-Sectional Study

Background: Congenital hypothyroidism (CH) can influence neonates’ neurodevelopment. There are controversies on the cause of infantile hypothyroidism and its relationship with maternal hypothyroidism. Objectives: This study aimed to investigate the relationship between maternal hypothyroidism and the incidence of CH. Methods: This cross-sectional study was conducted on 712 newborns with hypothyroidism born in Fars province, Iran, between 2018 and 2020, identified through the national screening program for genetic, metabolic, and endocrine congenital diseases recruited by the census sampling method. The information on infants’ files was recorded in a researcher-made checklist. Descriptive data were reported by mean ± SD and No. (%). The independent t-test, chi-square test, Pearson correlation, and Spearman’s rank correlation coefficient were used to evaluate relationships between variables. Results: Of 179,448 infants screened, 712 (4 of 1,000 live births) had CH with a mean thyroid stimulating hormone (TSH) level of 22.34+24.8 mlU/L. Of these, 252 infants (35.4%) had a family history of hypothyroidism in the mother (OR = 4.951, P < 0.001). There was a significant relationship between CH and maternal hypothyroidism. Moreover, there was a significant difference in the mean TSH level between hypothyroid infants born to mothers with a history of hypothyroidism (19.10 ± 21.30 mlU/L) and those who had healthy mothers (24.23 ± 26.44 mlU/L, P = 0.027). The prevalence of CH in 2018, 2019, and 2020 were reported to be 0.34%, 0.4%, and 0.45%, respectively. Conclusions: Our results showed a significant relationship between maternal hypothyroidism and CH. Considering the importance of the prompt diagnosis of CH, especially in high-risk groups such as infants of hypothyroid mothers, it is recommended to conduct more studies to design more precise guidelines to screen infants who are at risk of CH.

Dynamic Screening of Thyroid Function for the Timely Diagnosis of Congenital Hypothyroidism in Very Preterm Infants: A Prospective Multicenter Cohort Study.

Background: Preterm infants presented a high prevalence of congenital hypothyroidism (CH), while the optimal screening pattern is still under debate. This study aimed at evaluating the characteristics of thyroid function by conducting weekly screening during the first month of life in very preterm infants (VPIs) to achieve timely diagnosis and treatment of CH. Methods: A prospective cohort study was carried out on VPIs born with gestational age (GA) <32 weeks (w) and admitted to the participating institutes from January 1, 2019 to December 31, 2022. Serial serum thyroid hormone levels were measured weekly within the first month after birth, and at 36 w of corrected age, or before discharge. Datasets for serial thyroid hormone levels and general information were obtained. Results: A total of 5992 VPIs were enrolled in this study, of which 456 (7.6%) [95% confidence interval (CI), 6.9-8.3%] were diagnosed with CH. The incidence of CH increased with lower GA, moving from 4.8% [CI, 3.4-6.1%] at GA 31 w to 16.9% [CI, 8.3-25.4%] at GA <26 w. Among the CH subjects, 57.7% [CI, 53.1-62.2%] were identified after the first screening and classified as delayed thyrotropin elevation (dTSH). With the decrease of GA, the proportion of dTSH also increased, moving from 38.1% [CI, 27.5-48.7%] at GA 31 w to 82.6% [CI, 65.8-99.4%] at GA <26 w. Through conducting weekly screening of thyroid function, it was remarkable that only 42.3% [CI, 37.8-46.9%] of CH subjects were diagnosed during the first screening. The cumulative rate of CH identified by rescreening performed at the second, third, and fourth week was 76.1% [CI, 72.2-80.0%], 90.6% [CI, 87.9-93.3%], and 98.9% [CI, 97.9-99.9%], respectively. Conclusion: The incidence of CH and dTSH both increase with lower GA in VPIs. Dynamic screening of thyroid function by weeks within the first month of life is crucial for the timely diagnosis and treatment of CH in VPIs, and it might effectively reduce the implications of missed diagnosis and delayed treatment. Clinical Trials Registration: ChiCTR1900025234 and ChiCTR2000037918 (Registration number).

Increased incidence of congenital hypothyroidism in China: An analysis of 119 million screened newborns.

Despite the lack of nationwide epidemiological studies, congenital hypothyroidism (CH) incidence in China has increased. We aimed to evaluate the trends of CH and the possible reasons behind them. Data from screened newborns from the Chinese Newborn Screening Information System from 2012 to 2019 was collected. We applied the Bayesian hierarchical Poisson regression model and meta-analysis to estimate incidence or proportion over the years. The estimated CH incidence increased from 4.01 per 10,000 births in 2012 to 5.77 per 10,000 births in 2019. The average annual growth rate (ARG) of CH incidence for all provinces varied from 0.59 to 20.96%. The most rapid rise in incidence was observed in cases with an initial thyroid stimulating hormone (TSH) concentration of < 10 mIU/L. The meta-analysis results showed that the proportion of permanent CH increased by 0.024% (95%CI: 0.011%, 0.037%) annually. Each 1 mIU/L decrease in TSH cutoff value was associated with a 2.96% increase in CH incidence. In the same period, the proportion of premature CH cases increased from 6.60 to 9.10%, which was much higher than the increase in preterm births. A significant relationship was not found between provincial growth rates in screening coverage and provincial baseline incidences of CH. Conclusion:CH incidence has substantially increased in China. The slight adjustment of the TSH cutoff value and increasing preterm birth rate contribute to such a trend; however, the contribution is limited. What is Known: • An uptrend in congenital hypothyroidism (CH) incidence has been reported in many European and American countries in the last two decades; however, no studies have been conducted in China to explain the increased CH incidence. • We provide a detailed epidemiological report on the trends of CH during 2012-2019 in China, with an attempt to explore the reasons behind it. What is New: • This first-ever national-wide epidemiological report in China showed an uptrend in CH incidence with variations over regions and CH subtypes. The mild lowering of TSH cutoff values and the increasing preterm birth rate contributed to this uptrend.

Neonatal screening for congenital hypothyroidism in Sweden 1980-2013: effects of lowering the thyroid-stimulating hormone threshold.

This study aims to evaluate the neonatal screening for congenital hypothyroidism (CH) and the diagnosis CH in the national health registers and to study the effects of lowering screening thyroid-stimulating hormone (TSH) threshold on the incidence of CH and birth characteristics of screening positive and negative CH children. This is a nationwide register-study of all children (n = 3 427 240) in the Swedish Medical Birth Register (MBR) and national cohort for screening positive infants (n = 1577) in 1980-2013. The study population was further linked to several other Swedish health registers. Evaluation of the CH screening and CH diagnosis was performed with levothyroxine use in the first year of life as reference. The incidence of CH was estimated by the Clopper-Pearson method. Regression models were used to study associations between CH and birth characteristics. The neonatal CH screening had high efficacy, but 50% of all children with a CH diagnosis were screening negative. The incidence of screening positive CH increased (1/3375 to 1/2222), and the incidence of screening negative CH decreased (1/2563 to 1/7841) after lowering the TSH screening threshold in 2009. Screening negative CH was associated with female sex, twinning, prematurity, low birth weight, birth defects, and need of neonatal intensive care, and 42% had transient disease. Despite high efficacy of the CH screening, 50% of children diagnosed as CH was screening negative. Although other factors influencing the incidence of the CH diagnosis cannot be ruled out, the incidence of screening negative CH decreased with lowering of the TSH threshold. Birth characteristics differed between screening positive and negative CH.

Congenital hypothyroidism in Northern Ireland: 40years' experience of national screening programme.

The incidence of congenital hypothyroidism (CHT) has progressively increased in several regions around the world but has yet to be evaluated in Northern Ireland (NI). CHT screening programme was introduced in NI in 1980 and has had a relatively unchanged protocol since its inception. The purpose of the study was to evaluate the incidence of CHT in NI from 1981 to 2020 and to explore possible contributing factors to any changes seen over the 40-year period. This was a retrospective database review of children diagnosed with CHT in NI between 1981 and 2020. Data was collected from the patients' medical (paper and electronic) records, including epidemiological, clinical, laboratory, and radiological features as well as outcomes at 3 years. Of 800,404 new-borns who were screened for CHT in NI between January 1981 and March 2020, 471 were diagnosed with CHT. There was a steady and significant increase in incidence of CHT over time with an incidence of 26 cases per 100,000 livebirths in 1981 versus71 cases per 100,000 in 2019 (p < .001). Of these 471, 77 new-borns (16%) were born preterm. The incidence of CHT was observed twice as much in female compared to male new-borns. Diagnostic imaging including radioisotope uptake and thyroid ultrasound scans were performed in 143 cases (30%). Of these, 101 (70%) cases had thyroid dysgenesis and 42 (30%) cases had thyroid dyshormonogenesis. There were 293 (62%) of 471 patients had confirmed permanent CHT, and 90 patients (19%) had transient CHT. Over that period at least 95% of the population were recorded as having United Kingdom/Ireland as country of birth. Our findings demonstrate a nearly tripling of the CHT incidence observed over the last 40 years. This is against a background of a relatively stable population demographics. Future research should focus on the underlying cause(s) of this condition which may include changing environmental exposures in utero.

Epidemiological profile of congenital hypothyroidism at a southern Brazilian state.

To determine the incidence of congenital hypothyroidism (CH) over a 10-year period at the Reference Service in Neonatal Screening of the state of Rio Grande do Sul (RSNS-RS). Historical cohort study including all newborns screened for CH by the RSNS-RS from January 2008 until December 2017. Data of all newborns with neonatal TSH (neoTSH; heel prick test) values ≥ 9 mIU/L were collected. According to neoTSH values, the newborns were allocated into two groups: Group 1 (G1), comprising newborns with neoTSH ≥ 9 mIU/L and serum TSH (sTSH) < 10 mIU/L, and Group 2 (G2), comprising those with neoTSH ≥ 9 mIU/L and sTSH ≥ 10 mIU/L. Of 1,043,565 newborns screened, 829 (0.08%) had neoTSH values ≥ 9 mIU/L. Of these, 284 (39.3%) had sTSH values < 10 mIU/L and were allocated to the G1 group, while 439 (60.7%) had sTSH ≥ 10 mIU/L and were allocated to the G2 group, and 106 (12.7%) were considered missing data. The overall incidence of CH was 42.1 per 100,000 newborns screened (95% confidence interval [CI] 38.5-45.7/100,000) or 1:2377 screened newborns. The sensibility and specificity of neoTSH ≥ 9 mIU/L were 97% and 11%; of neoTSH 12.6 mUI/L, 73% and 85% respectively. In this population, the incidence of permanent and transitory CH was 1:2377 screened newborns. The neoTSH cutoff value adopted during the study period showed excellent sensibility, which matters for a screening test.

Incidence of congenital hypothyroidism in Lithuania: data from the National New-born screening program, 2002-2019

Searchable abstracts of presentations at key conferences in endocrinology ISSN 1470-3947 (print) | ISSN 1479-6848 (online)

A Rare Case of Congenital Hypothyroidism

Congenital Hypothyroidism (CH) is a common preventable cause of mental retardation. The incidence of CH is 1 in 2500 to 1 in 3000 newborns. Most common causes are thyroid dysgenesis and dyshormonogenesis. Some disorder like maternal autoantibodies, maternal intake of anti thyroid medication, iodine deficiency or iodine excess can result in transient CH. Common symptoms include decreased activity and increased sleep, feeding difficulty, constipation, and prolonged jaundice. In this case report, A 3 day old baby was admitted to SNCU with chief complain of yellowish discoloration upto abdomen and respiratory distress. On examination, common signs include myxedematous facies, large fontanels, macroglossia, a distended abdomen with umbilical hernia, and hypotonia. Thyroid dysgenesis accounts for 85% of permanent, primary CH, while inborn errors of thyroid hormone biosynthesis (dyshormonogeneses) account for 10-15% of cases. Secondary or central CH may occur with isolated TSH deficiency, but more commonly it is associated with congenital hypopitiutarism. Transient CH most commonly occurs in preterm infants born.

Has air pollution any role in the incidence of congenital hypothyroidism?

Has air pollution any role in the incidence of congenital hypothyroidism?

Neonatal screening for congenital hypothyroidism (CH) in preterm infants. Is a targeted strategy required?

Premature infants are at higher risk of developing congenital hypothyroidism (CH) but the neonatal screening strategy for this population is still debatable. The purpose of this retrospective study is to describe the results of a screening program for CH in a preterm infant cohort. All preterm newborns who underwent neonatal screening in the Italian region of Piedmont in the period January 2019 - December 2021, were included in this retrospective cohort study. The first TSH measurement was performed at 72h, while the second at 15 days of life. Infants with TSH >20 mUI/l at first detection and >6 mUI/l at second were recalled for a full evaluation of thyroid function. During the study period, 5930 preterm newborns were screened. Based on birth weight (BW), the mean TSH was 2.08±0.15 for BW<1000 g, 2.01±0.02 for BW 1001-1500 g, 2.28±0.03 for BW 1501-2499 g and 2.41±0.03 mUI/l in normal-weight newborns (p<0.005) at the first detection, with a significant difference observed at the second measurement (p<0.005). Based on gestational age, the mean TSH at first detection was 1.71±0.09 mUI/l for extremely preterm babies and 1.87±0.06, 1.94±0.05 and 2.42±0.02 mUI/l for very preterm, moderately, and late preterm infants (p<0.005), respectively. Significant between-group differences of TSH measurements were also at the second and third detections (p < 0.005 and p = 0.01). The 99% reference range in this cohort overlapped with the recommended TSH cut-offs for screening recall (8 mUI/l for first detection and 6 mUI/l for second detection). CH incidence was 1:156.Of the 38 patients diagnosed with CH, a eutopic gland was present in 30 (87.9%), with CH transient in 29 (76.8%). We observed no significant difference in the recall rate between preterm and at term infants screened in this study. Our current screening strategy therefore appears effective in avoiding misdiagnosis. CH screening approaches vary among countries. Development and testing of a uniform multinational screening strategy is needed.

Guidelines for Newborn Screening of Congenital Hypothyroidism (2021 Revision)

Purpose of developing the guidelines: Newborn screening (NBS) for congenital hypothyroidism (CH) was started in 1979 in Japan, and early diagnosis and treatment improved the intelligence prognosis of CH patients. The incidence of CH was once about one in 5,000-8,000 births, but has been increased with diagnosis of subclinical CH. The disease requires continuous treatment and specialized medical facilities should conduct differential diagnosis and treatment in patients who are positive by NBS to avoid unnecessary treatment. The Guidelines for Mass Screening of Congenital Hypothyroidism (1998 version) were developed by the Mass Screening Committee of the Japanese Society for Pediatric Endocrinology in 1998. Subsequently, the guidelines were revised in 2014. Here, we have added minor revisions to the 2014 version to include the most recent findings. Target disease/conditions: Primary congenital hypothyroidism. Users of the Guidelines: Physician specialists in pediatric endocrinology, pediatric specialists, physicians referring pediatric practitioners, general physicians, laboratory technicians in charge of mass screening, and patients.

Hypothyroidism in Saudi Arabia: review article

Thyroid hormone is necessary for the healthy development of the nervous system and adequate growth in the first several years of life. The pituitary gland regulates T3 and T4 levels through a feedback mechanism in healthy individuals. One of the most frequent worldwide causes of severe neurocognitive impairment and avoidable mental retardation is congenital hypothyroidism (CH). The incidence of CH was previously thought to be 1:3,000-4,000 live births, however, recent evidence indicated an upward trend. Thus, this review aimed to study the hypothyroidism trends in Saudi Arabia. Several factors could influence the occurrence of hypothyroidism, including age, sex, and other regional considerations. According to the Kingdom of Saudi Arabia, 15.5% of non-endocrine females with a body mass index of 20 or higher had hypothyroidism. Research has revealed a strong link between thyroid disorders and diabetes. According to studies, there is a direct link between high thyroid-stimulating hormone levels and coronary artery disease (CAD), making hypothyroidism a risk factor for CAD. Further, many studies added information demonstrating that hypothyroidism during pregnancy increases the risk of both maternal and newborn outcomes. To offer more precise information about the prevalence and effects of hypothyroidism, a population-based cohort study is required.

Hypothyroidism in Saudi Arabia: a review article

Thyroid hormone is necessary for the healthy development of the nervous system and adequate growth in the first several years of life. The pituitary gland regulates T3 and T4 levels through a feedback mechanism in healthy individuals. One of the most frequent worldwide causes of severe neurocognitive impairment and avoidable mental retardation is congenital hypothyroidism (CH). The incidence of CH was previously thought to be 1:3000–4000 live births, however, recent evidence indicated an upward trend. Thus, this review aimed to study the hypothyroidism trends in Saudi Arabia. Several factors could influence the occurrence of hypothyroidism, including age, sex, and other regional considerations. According to the Kingdom of Saudi Arabia (KSA), 15.5% of non-endocrine females with a BMI of 20 or higher had hypothyroidism. Research has revealed a strong link between thyroid disorders and diabetes. According to studies, there is a direct link between high TSH levels and coronary artery disease (CAD), making hypothyroidism a risk factor for CAD. Further, many studies added information demonstrating that hypothyroidism during pregnancy increases the risk of both maternal and newborn outcomes. To offer more precise information about the prevalence and effects of hypothyroidism, a population-based cohort study is required.

Etiological Profile, Targeted Levothyroxine Dosing and Impact of Partial Newborn Screening in Congenital Hypothyroidism-A Single Centre Experience.

Congenital hypothyroidism (CH) is the most common cause of preventable intellectual disability. Newborn screening (NBS) for CH has been in vogue in many parts of the world since 1970, but despite its well-known benefits, many developing countries including India have not been able to establish universal NBS for CH till date. The aim of this study was to review the clinical aspects of congenital hypothyroidism in a tertiary care university referral teaching hospital, focusing on aetiology of CH, predictors of permanence, optimal targeted dose strategies based on aetiology and the effect of newborn screening on the time to diagnosis. The electronic medical records of 233 children with CH referred to our centre between January 2009 and December 2019 were analysed. A partial NBS was established in the state in 2012. Dyshormonogenesis (57.5%) was the most common aetiology of CH. The incidence of transient CH in children with a gland in situ (GIS) was 35%. Levothyroxine (LT-4) dose of >2.75 μg/kg/day (sensitivity 76.5, specificity 72), >2.15 μg/kg/day (sensitivity 82.4, specificity 61.9) and >1.85 μg/kg/day (sensitivity 76.5, specificity 61.9) at years 1, 2 and 3, respectively, were predictors of permanent CH. An initial LT-4 dose ≥8 μg/kg was sufficient and very seldom led to undertreatment in children with dyshormonogenesis. On the contrary, even doses ≥13 mcg/kg/day led to frequent undertreatment in children with thyroid dysgenesis. After the introduction of newborn screening, the median age at diagnosis came down from 45 days (IQR 14-180 days) to ten days (IQR 3-12 days). Targeted dosing based on aetiology of CH may be more appropriate to optimise outcomes. The time to diagnosis of CH reduced significantly after the adoption of even a partial NBS program highlighting the urgent need for implementation of the same in resource poor settings.

Effect of perinatal factors on neonatal thyroid stimulating hormone

Background: Congenital Hypothyroidism (CH) is a common cause of mental retardation. Its incidence varies in different parts of the world from 1:4000 to 1:2000. Objective: To study effect of perinatal factors on heel prick blood TSH levels and to find incidence of congenital hypothyroidism. Study Design: Prospective Observational birth cohort study. Method: Heel prick blood samples of total 3151babies, 1673 (53.1%) males and 1478 (46.9%) females was taken on special graded filter paper within 48 hours of life and screened by fluoroimmunometric assay. Babies with TSH value more than 9µU/ml were recalled at 5 to 7 days of life for repeat sample of T3, T4, TSH. Babies with low T4 less than 7 µgm/dl and TSH more than 20 µU/ml were labelled as congenital hypothyroidism. The effect of perinatal factors was analyzed statistically. Result: In our study, thyroid screening in two third of neonates was done at 12 to 24 hours of age. Median (IQR) TSH of 3151 neonates was 3(1.4-5.5) µU/ml. TSH level was significantly low in neonates with sampling at age of >24 hours. Recall rate in our study was 7.6% (238 cases) and 2 neonates were diagnosed as congenital hypothyroidism. Neonates with assisted deliveries showed a higher median (IQR) TSH level 5.3(3-9.1µU/ml) as compared to normal vaginal deliveries and lower segment caesarean section. This was statistically significant (p

Hypothyroidism in First-Degree Relatives of Neonates with Congenital Hypothyroidism: Is there an Association?

Recent studies have shown an increased incidence of congenital hypothyroidism (CH), especially in the middle-east region. The exact etiology is unknown; however, it has been related to several factors, the most noticeable being the high prevalence of transient CH (TCH), parental consanguinity, and the history of hypothyroidism in relatives. We sought to determine the impact of hypothyroidism in the relatives of patients with the observed trend. We included all patients with primary CH detected through the Newborn Screening (NBS) Program from 2007 to 2016. We analyzed the impact of consanguinity relationship, parental and siblings' thyroid function, second-degree relatives' thyroid function, parental educational level, age, and maternal gestational diabetes on the development of permanent CH (PCH) and TCH. A total of 1447 consecutive eligible patients were recruited during the study period. Of this number, 1171 (81%) were diagnosed with CH: 623 (53.2%) had PCH and 548 (46.8%) had TCH. Six hundred thirty-three (54.1%) participants were men, and 814 (69.5%) had a history of relatives' hypothyroidism. Our data analysis revealed a significant difference regarding the male gender, having a history of relatives' hypothyroidism, and parental hypothyroidism compared to TCH ones (P < 0.05). Patients with a history of relatives' hypothyroidism had significantly higher PCH than TCH (P < 0.0001). However, consanguineous marriage was not comparable in patients regardless of their history of relatives' hypothyroidism (P-value >0.884). Our findings indicated the role of the history of hypothyroidism in neonates' relatives in the evolution of the PCH. Meanwhile, consanguineous marriage did not impress the development of PCH and TCH.

Evaluation of the results of the 10-year screening program for neonatal metabolic and endocrine diseases: The case of Sivas province, Türkiye

Amaç: Bu çalışmada Sivas’ta 2011-2021 yıllarındaki yenidoğan metabolik ve endokrin hastalık tarama programı sonuçlarının değerlendirilmesi amaçlandı. Yöntem: Kesitsel tipteki bu çalışmada, Sivas Neonatal Tarama Programı kapsamında 2011-2021 yılları arasında topuk kanı alınmış 84044 yenidoğanın Neonatal Tarama Programı Web Uygulaması üzerinden cinsiyet, doğum ağırlığı, doğum tarihi ve numune alınma tarihlerine ulaşıldı. Yıllara göre fenilketonüri, konjenital hipotiroidi, biyotinidaz eksikliği, kistik fibrozis ve konjenital adrenal hiperplazi tanısı almış yenidoğan sayı ve oranları belirlendi, hastalık insidansları hesaplandı. Bulgular: Taranan hastalık insidanslarının en düşük ve en yüksek değerleri sırasıyla konjenital hipotiroidi için 1:1011- 1:233, fenilketonüri için 1:8375- 1:657, biyotinidaz eksikliği için 1:6815- 1:1861, kistik fibrozis için 1:7902- 1:3614 ve konjenital adrenal hiperplazi için 1:6815- 1:3222 idi. Konjenital hipotiroidi insidansı, taraması yapılan diğer hastalıkların insidansından daha yüksekti. İnsidansı en yüksek ikinci hastalık ise fenilketonüri idi. Taranan beş hastalık için de cinsiyete göre anlamlı bir fark yoktu. Konjenital hipotiroidi (p=0.002) ve konjenital adrenal hiperplazi (p=0.039) tanısı alanların doğum ağırlıkları daha düşüktü. Sonuç: Taraması yapılan hastalıklardan konjenital hipotiroidi ve fenilketonüri insidanslarının daha yüksek olduğu bulundu. Konjenital hipotiroidi ve konjenital adrenal hiperplazi tanısı alanların doğum ağırlıkları daha düşüktü. Erken tanı ve müdahaleyle önlenebilir veya tedavi edilebilir hastalıklar olan bu hastalıklarda tarama yapılmasının öneminin ailelere anlatılması, diğer benzer hastalıkların da tarama programına alınması önerilebilir.

The incidence of congenital hypothyroidism in neonates born in Chaharmahal and Bakhtiari province from 2015 to 2021; A cross-sectional study

Introduction: Congenital hypothyroidism (CH) is one of the most common endocrine and metabolic disorders and a common preventable cause of mental retardation across the world. This disorder can be prevented if diagnosed and treated before the age of four weeks. Objectives: This study was performed to investigate the incidence rate of CH in infants in Chaharmahal and Bakhtiari province. Patients and Methods: The data of this study were obtained by the CH screening program from 2015 to 2021 in the health deputy of Chaharmahal and Bakhtiari province. Results: A total of 651 patients were diagnosed with CH, which showed an incidence rate of 5.06 per 1000 births (1 per 198 live births) in the province. The highest incidence of the disease was obtained in 2016 and the lowest incidence in 2021. Lordegan city had the highest incidence rate (8.1 per 1000 live births) and Kiar had the lowest one (1.67 per 1000 live births) during the study period. Moreover, the highest and lowest incidence rates in terms of season were observed in winter and summer, respectively. Conclusion: It can be concluded that Chaharmahal and Bakhtiari province, especially Lordegan, is one of the regions with high prevalence of CH in Iran, therefore the incidence rate is not only higher than the national average but also higher than the global average. Hence, the potential causes of this observation deserve further investigation.

ESTABLISHING A NATIONWIDE NEWBORN SCREENING PROGRAM FOR CONGENITAL HYPOTHYROIDISM: A SYSTEMATIC REVIEW

Objective: The congenital hypothyroidism (CH) is a treatable hormonal disease that if left untreated in neonates, results in irreversible mental retardation. Newborn screening for CH and thyroid hormone replacement therapy started within two weeks of age can control cognitive development. This study aimed to estimate CH incidence in Pakistani population. Material and Methods: Electronic databases and the bibliography of articles were searched, and a systematic review of publications reporting the incidence of CH in Pakistan was carried out. The studies fulfilling the following criteria were analyzed: retrospective and prospective studies, adult population; pediatric population; Thyroid Stimulating Hormone (TSH); Dried Blood Spot (DBS); serum testing quantitative; English language. Results: We identified nine studies that narrated the incidence of CH in our country. According to this systematic review, the maximum estimated incidence of CH was 1:1600 reported for Pakistani population. Compared to the incidence of CH from other parts of the world (1:2000-1:4000), incidence from Pakistan is high. Conclusion: According to these findings, this high incidence highlights the need for a National Newborn Screening (NBS) program for CH. We have proposed a strategy for establishing a nationwide NBS program for CH. Key Words: Newborn screening, Congenital hypothyroidism, Pakistan, Thyroid-stimulating hormone, Mental retardation

Incidence tendency, etiological classification and outcome of congenital hypothyroidism in Guangzhou, China: an 11-year retrospective population-based study.

An increased incidence of congenital hypothyroidism (CH) has been described worldwide over theyears. In this study, we aimed to investigate the epidemiologic characteristics of CH, the iodine status in Guangzhou, China and to investigate which factors might influence the CH incidence during the period 2010-2020. We retrospectively reviewed all cases of CH detected by newborn screening during the period 2010-2020. CH was classified as either suspected thyroid dyshormonogenesis (SDH) or thyroid dysgenesis (TD) based on thyroid ultrasound at first diagnosis. Patients were re-evaluated after 4weeks of L-thyroxine withdrawal at age of 2-3years to confirm the diagnosis of permanent CH (PCH) or transient CH (TCH). From 2010 to 2020, 1,655 patients with CH were confirmed from 2,400,383 newborns (1:1,450). The CH incidence increased from 1:2,584 in period [2010-2014] to 1:1,086 in period [2015-2020]. Among the 1,337 patients with thyroid ultrasound, 84.29% were SDH whereas 15.71% had TD. Further analysis revealed that more SDH (78.32%) were TCH whereas more TD (87.12%) turned to be PCH. The proportion of blood spot thyrotropin values >5mIU/L ranged from 8.03 to 20.46%, indicating iodine deficiency. The prevalence of preterm infants increased from 5.50% inperiod [2010-2014] to 7.06% in period [2015-2020] (p<0.001). In the past decade, the CH incidence has increased progressively. SDH was the majority of CH, most of which were TCH, while most patients with TD were PCH. The increased incidence might be mainly due to iodine deficiency and increased rates of preterm infants in our study.