Permanent and transient congenital hypothyroidism in Fayoum, Egypt: a descriptive retrospective study

Diagnostic options, physiopathology, risk factors and genetic causes of permanent congenital hypothyroidism: A narrative review

Background

In Permanent congenital hypothyroidism (PCH) is a lifelong condition characterized by a deficiency in thyroid hormone, leading to various neurodevelopmental complications. Early clinical signs are often nonspecific and easily overlooked, but newborn screening programs have improved early detection.

Methods

This narrative review aims to provide insights comparatively transient and permanent PCH and also the diagnosis, risk factors, underlying pathophysiology, and genetic causes associated with PCH. Relevant studies were identified through a comprehensive search using the term 'Permanent congenital hypothyroidism' (Mesh) across scientific databases of electronic databases such as PubMed, Scopus, and Web of Science.

Results

Prompt initiation of thyroid hormone replacement therapy, particularly within the initial two weeks postpartum, crucially enhances neurocognitive development outcomes. Multiple predictive approaches, encompassing screening TSH levels, maternal thyroid history, and levothyroxine dosage per kilogram assessment, aid in identifying PCH. Recent studies have demonstrated a mounting prevalence of PCH, contributing significantly to the overall rise in CH incidence. Genetic factors, primarily DUOX2 and DUOXA2 mutations, alongside environmental influences such as post-term birth, low birth weight, and macrosomia, may induce PCH. Nonetheless, reliable markers for early PCH prediction upon diagnosis remain elusive, leading to delayed recognition post-ceasing levothyroxine treatment around age 3.

Conclusions

Recent studies have observed an increased incidence of PCH, contributing substantially to the overall rise in cases of congenital hypothyroidism. Understanding the diagnostic options and genetic etiologies associated with PCH is crucial for the early identification and appropriate management.

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

Background

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

Methods

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

Findings

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

Interpretation

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

Funding

The study was not funded by any source.

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.

Physical and mental growth and development in children with congenital hypothyroidism: a case-control study

Introduction

The clinical complications of congenital hypothyroidism such as brain disorders are very subtle and are not recognizable in infancy period. They are recognizable when it is too late for treatment or prevention. General screening of newborns is effective in diagnosing congenital hypothyroidism and initiating initial treatment. The aim of this study is to compare the physical and mental growth pattern of children with congenital hypothyroidism with healthy ones.

Methods

This case–control study was performed on 34 patients and 68 healthy children who were matched in terms of inclusion and exclusion criteria. Children development screening test (ASQ), children development assessment test (Bayley), preschool Wechsler intelligence scale (WPPSI) and age and steps questionnaire of emotional social development (ASQ-SE) were completed by trained questioners. Data were analyzed using STATA software.

Results

The results indicated that there was no significant difference between the mean of verbal (P = 0.77), non-verbal (P = 0.81) and general (P = 0.66) IQ in permanent and transient patients and healthy individuals. Also, there was no significant difference between the mean of different ranges of ASQ test (including communication, delicate and large movements, problem solving and social) at 12 months and 42 months (P < 0.05). According to Bayley test, there was no significant difference between the cases (permanent and transient) and controls in the cognitive (P = 0.42) and expressive (P = 0.38) categories. The difference was significant in the perceptual (P = 0.011), large (P = 0.03) and delicate (P = 0.04) movements categories.

Conclusion

This study emphasized on the high effectiveness of neonate hypothyroidism screening program, so that the difference between 3.5 years old children with and without this disease has decreased significantly. Early diagnosis of the patients, while creating beneficial effects for patients and increasing quality of life, cause reduction in the long-term costs of the health system.

Prevalence and predictive factors of transient and permanent congenital hypothyroidism in Fars province, Iran

INTRODUCTION

There is no data on the number as well as the prevalence of congenital hypothyroidism (CH) in the Fars province. Hence, we designed this study to analyze the latest data and the possible predictive factors on transient and permanent CH in this province.

METHOD

This cross sectional study is based on the Fars province screening data from 2013 to 2016. A total of 294,214 newborns were screened with 938 confirmed cases of CH, which were included in this study. After recall and completion of the missing data, follow-up data for 642 CH cases with thyroid stimulating hormone (TSH) concentrations and levothyroxine doses for ten outpatient visits and final transient vs. permanent CH diagnosis were included.

RESULTS

The incidence rate was 1:313.66, and out of the 642 CH cases, 66.04 % had permanent CH, while 33.96 % had transient CH. TSH level trend during the outpatient visits were not statistically different between the two groups (P = 0.312). A cutoff point of > 2.25 levothyroxine µg/kg (sensitivity: 76.11 %, specificity: 58.52 %) at the third year and a TSH concentration of > 43.35 mIU/L at the venous sampling (initial TSH) (sensitivity: 31.66 %, specificity: 90.32 %) were the predictive factors for permanent CH.

CONCLUSION

Fars province has one of the highest incidence rate of CH in Iran. Levothyroxine dose at the 3rd year and the 1st venous TSH sample are the predictive factors for permanent CH in the Iranian population; however, TSH concentrations during follow ups are unreliable predictors.

Validity of Six Month L-Thyroxine Dose for Differentiation of Transient or Permanent Congenital Hypothyroidism

OBJECTIVE

The tendency to reduce thyroid stimulating hormone (TSH) referral cut-off values in congenital hypothyroidism (CH) neonatal screening programs has resulted in an increase in the incidence of CH, but also the referral of infants with mild transient elevation of TSH. Therefore, there is a need to develop markers for differentiation of transient elevated TSH and permanent CH as early as safely possible to avoid unnecessary treatment. The aim was to evaluate sixth-month L-thyroxine (LT4) dose as a predictive marker for differentiation of transient elevated TSH and permanent CH.

METHODS

Data of patients who had been followed after referral from the neonatal screening programme between the year 2010 and 2019 in a tertiary pediatric endocrine centre were examined retrospectively.

RESULTS

There were 226 cases referred, of whom 186 (82.3%) had eutopic thyroid gland, and 40 (17.7%) had dysgenetic gland. In patients with a dysgentic gland there was a non-significant tendency to have lower diagnostic free thyroxine concentration but significantly higher TSH compared with those with eutopic gland (p=0.44 and p=0.023, respectively). Patients with thyroid dysgenesis required higher initial and six month LT4 doses compared with those with eutopic glands (p=0.001). Receiver operator curve analysis showed the optimum cut-off value for LT4 at six months for transient vs. permanent CH was 2 μg/kg/day (sensitivity 77% and specificity 55%), regardless of etiology. Similarly, in patients with eutopic glands the optimum cut-off value for LT4 dose at six months for permanent vs. transient patients was 2 μg/kg/day (sensitivity 72% and specificity 54%).

CONCLUSION

Results suggest that LT4 requirement at six months of therapy may be a good marker for predicting transient TSH elevation in patients with eutopic thyroid gland, thus facilitating the decision to halt LT4 therapy.

Congenital hypothyroidism in different cities of the Isfahan province: A descriptive retrospective study

BACKGROUND

Considering the high prevalence rate of congenital hypothyroidism CH in Iran, an epidemiological study in each region would be helpful in understanding the etiology of the disorder and providing preventative strategies in this field. This study aims to determine the prevalence of CH in different cities of the Isfahan province.

MATERIALS AND METHODS

This descriptive and retrospective study was conducted among 918 primarily diagnosed CH neonates, who have been identified through the neonatal screening program from 2009 to 2015. At the age of ≥3 years, treatment was discontinued for 4 weeks, and T4 and thyroid-stimulating hormone were measured. Permanent (PCH) or transient (TCH) was determined from the results of the thyroid function tests.

RESULTS

From 389,101 screened neonates, 918 were diagnosed with primary CH. The overall prevalence rate of CH was 2.36 in 1000 live birth (ranged 1.58-7.22 in 1000 live birth in different cities). The highest prevalence rate of CH was reported in Ardestan, Khansar, Golpaygan, and Nain cities with prevalence rate of 4.86-7.22 in 1000 live birth and lowest prevalence occurring in Fereydan, Shahreza, Isfahan, and Mobarakeh cities with prevalence rate of 1.58-1.89 in 1000 live birth. In 392 cases which reached to 3 years of age, the rate of TCH was 47.45%. In Chadegan, Natanz, Fereydunshahr, Shahinshahr, Najafabad, Dehaghan, Borkhar, and Mobarakeh, the prevalence of PCH was <50%.

CONCLUSION

The current findings indicate that the incidence rate of both PCH and TCH are high in Isfahan province with significant variability in different cities which could be due to the role of different genetic, prenatal, and different environmental factors. These epidemiological data could be used as baseline date to design more etiological studies.

Determining the TSH reference range in national newborn screening program for congenital hypothyroidism

Objective: Since the initiation of the thyroid screening program in Iran in 2005, 5 mIU/L has been selected as the threshold for thyroid stimulating hormone (TSH) for screening for congenital hypothyroidism. Given the specific disease pattern in the region and current controversies of the TSH cutoff point, a new cutoff point has been proposed in this study.Methods: This study was conducted on the existing database of the screening program consisting of 127,112 neonates in Markazi Province, center of Iran, during 2006-2012. Data on 614 referred neonates consisting of 414 neonates diagnosed of having hypothyroidism and 200 screened healthy neonates, were analyzed. The heel prick test had been done on the studied neonates to determine the TSH levels. The receiver-operator characteristic (ROC) curve and diagnostic values were used for data analysis.Results: The 5-mIU/L cutoff point in the study had a sensitivity and specificity and AUC of 86.5, 10 and 47%, respectively. Among the eleven selected cutoff points, 6.5 mIU/L had the appropriate sensitivity, specificity and AUC (58.9, 56.5 and 57%, respectively), negative and positive likelihood ratios (0.73 and 1.35, respectively).Conclusion: Given the very low specificity of the 5-mIU/L cutoff point for referral and with respect to the high rate of referrals and many false positive cases, we suggest to use the 6.5-mIU/L cutoff point which is more suitable.

Higher Incidence Rates of Hypothyroidism and Late TSH Rise in Preterm Very-Low-Birth-Weight Infants at a Tertiary Care Center

BACKGROUND/AIMS

Preterm newborns with a very low birth weight (VLBW) of < 1,500 g have an atypical form of hypothyroidism with a delayed rise in TSH, necessitating a second newborn screening specimen collection. The aims of this study were to survey the compliance with second newborn screening to detect delayed TSH rise in VLBW preterm infants at a tertiary care center, and to determine the rate of atypical hypothyroidism.

METHODS

Retrospective review of the records of 104 preterm VLBW infants. Late TSH rise was defined as an increase in TSH concentration after 14 days of age in the presence of a normal initial screen.

RESULTS

The compliance rate was 92% for the second screening. High rates of hypothyroidism (16.3%) and of late TSH rise (4.8%) were detected. Patients with hypothyroidism had a significantly lower birth weight (p = 0.01) and longer hospital stay (p = 0.004). Patients with late versus those with early TSH rise had a significantly lower mean birth weight (851 ± 302 vs. 1,191 ± 121 g, p = 0.004).

CONCLUSION

The rates of early and late TSH rise in this VLBW population were higher than those in the literature and could be due to the use of povidone-iodine disinfectants. The yield of a second TSH screening in this study was high indicating the need for vigilance in screening VLBW preterm infants.

Rectal Levothyroxine for the Treatment of Hypothyroidism: A Case Study

Transient hypothyroidism can present itself as clinically asymptomatic or with few symptoms. Early treatment with levothyroxine (L-T4) prevents complications related to this disorder. We report a case of a male infant with concomitant short bowel syndrome and transient hypothyroidism treated with rectal L-T4. A 4-month-and-10-day-old boy with previous gastroschisis underwent multiple surgical approaches for small bowel resection and developed short bowel syndrome. We suspected hypothyroidism because of jaundice (direct bilirubin up to 59 mg/dL), the absence of evacuation, oral diet intolerance, and intestinal dysmotility. Because of a thyrotropin level of 34.45 μIU/mL and a free thyroxine level of 0.64 ng/dL, the diagnosis was confirmed. Because fasting was demanding, we started the patient on rectal diluted L-T4. After 4 weeks, the patient had spontaneous peristalsis, improvement of jaundice (direct bilirubin: 4.6 mg/dL), and normalized free thyroxine and thyrotropin values. In the present case, the patient was diagnosed with hypothyroidism and was on absolute fasting. An alternative route of drug administration was warranted. We empirically prescribed rectal diluted L-T4 when intravenous and suppository L-T4 were not available. This method was proven to be safe and effective in improving the patient's clinical and biochemical status. Rectal L-T4 is a possible alternative route of administration to treat hypothyroidism in patients who are unable to take the medication orally.

The etiologies and incidences of congenital hypothyroidism before and after neonatal TSH screening program implementation: a study in southern Thailand

BACKGROUND

Congenital hypothyroidism (CH) is one of the common causes of intellectual disability which can be prevented by early detection of an elevated thyroid stimulating hormone (TSH) level in the newborn and by treatment with thyroxine. In Thailand, neonatal TSH screening was implemented nationwide in 2005. The objective of the study was to determine the etiologies and the estimated incidences of CH in southern Thailand before and after the implementation of a neonatal TSH screening program in 2005.

METHODS

The medical records of pediatric patients who were diagnosed with primary CH at Songklanagarind Hospital during 1995-2013 were retrospectively reviewed. The study was divided into two time periods: study period 1 (SP1) (1995-2004) and study period 2 (SP2) (2005-2013), the time before and after TSH program implementation.

RESULTS

The most common form of CH during SP1 was overt permanent CH (66%), mostly caused by athyreosis or ectopic thyroid. In SP2, the most common form of CH was mild permanent CH (39%) (mostly due to dyshormonogenesis), followed by overt CH (32%) and transient CH (29%). The overall annual estimated incidence of CH per 10,000 live births in Songkhla Province was 1.69 (1:5021) in SP1, increasing to 4.77 (1:2238) in SP2; in all 14 provinces in southern Thailand, the estimated incidence was 1.24 (1:8094) in SP1 and 2.33 (1:4274) in SP2.

CONCLUSIONS

Neonatal TSH screening has a significant impact on the increased detection of the mild form of permanent and transient CH cases, which may be important for the prevention of brain damage from less severe CH although this remains to be documented.

A 7-year study on the prevalence of congenital hypothyroidism in northern Iran

Background

Congenital hypothyroidism (CH) is one of the most common congenital endocrine disorders.

The present study determined the prevalence and demographic characteristics of congenital hypothyroidism in the north of Iran.

Objective

To determine the prevalence of congenital hypothyroidism based on transient and permanent types with demographic characteristics in Mazandaran province in northern Iran.

Methods

This retrospective descriptive survey analyzed the medical records of children with primary diagnosis of CH in health centers in all cities of Mazandaran Province between June 2009 and March 2016. To compare the study groups (CH type) in terms of quantitative and qualitative variables, the t-test and Chi-square test were used, respectively using the SPSS22. P-value <0.05 was considered as significant.

Results

Of 269,088 infants screened during the study period, 548 infants with primary congenital hypothyroidism were identified (a prevalence of 1 per 491 births) and congenital hypothyroidism was definitively diagnosed in 389 children (a prevalence of 1 per 453 births); of them, 169 had permanent CH (a prevalence of 1 per 1043 births) and 220 had transient CH (a prevalence of 1 per 801 births). The female to male ratio in the permanent congenital hypothyroidism group was higher than that in the transient congenital hypothyroidism group (p=0.08). The family relationship between mother and father was stronger in the permanent congenital hypothyroidism group than in the transient congenital hypothyroidism group (p=0.03).

Conclusion

These findings show that congenital hypothyroidism is more prevalent in the north of Iran than in other areas of Iran; the prevalence of transient CH is particularly higher than permanent CH.

Transient hypothyroidism in the newborn: to treat or not to treat

Transient congenital hypothyroidism (CH) refers to a temporary deficiency of thyroid hormone identified after birth, with low thyroxine (T4) and elevated thyrotropin (TSH), which later recovers to improved thyroxine production, typically in first few months of infancy. Approximately 17% to 40% of children diagnosed with CH by newborn screening (NBS) programs were later determined to have transient hypothyroidism. Causes of transient CH are prematurity, iodine deficiency, maternal thyrotropin receptor blocking antibodies, maternal intake of anti-thyroid drugs, maternal or neonatal iodine exposure, loss of function mutations and hepatic hemangiomas. The classic clinical symptoms and signs of CH are usually absent immediately after birth in vast majority of infants due to temporary protection from maternal thyroxine. NBS has been largely successful in preventing intellectual disability by early detection of CH by performing thyroid function tests in infants with abnormal screening results. In this review we present the evidence for decision making regarding treatment vs. withholding treatment in infants with transient CH and present a rational approach to identifying transient CH based on American Academy of Pediatrics (AAP) recommendation.

Thyroid status of iodine deficient newborn infants living in central region of Turkey: a pilot study

BACKGROUND

Iodine deficiency (ID) during the fetal and neonatal periods can lead to neonatal hypothyroidism. This study was conducted to evaluate the effect of ID on the thyroid hormone level of newborns living in Turkey.

METHODS

Between 1998 and 2013, 71 newborns with a urinary iodine concentration <100 μg/L were recruited into the study. Data on thyroid volume, free triiodothyronine (fT3), free thyroxine (fT4), thyroid stimulating hormone (TSH), and thyroglobulin (Tg) were collected from all newborns, and on breast milk iodine from their mothers. Infants who were classified as having congenital hypothyroidism (TSH >40 mU/L and fT4 <8.5 pmol/L) were treated with levothyroxine (n=26, T group), while the remaining infants remained untreated (n=45, UT group). Thyroid hormones were subsequently measured 7-14 days later in a sub-sample of both treated and untreated infants.

RESULTS

The average values at the time of admission were as follows [median (min-max)]. fT3: 5.0 (2.8-7.1) pmol/L, fT4: 7.7 (0.13-19.1) pmol/L, TSH: 75 (14-426) mU/L, Tg: 464 (226-1100) ng/mL, urinary iodine concentration (UIC): 30 (0-61) μg/L, breast milk iodine levels: 21 (10-150) μg/L, thyroid ultrasound (USG): 1.10 (0.24-1.95) mL for the T group; and fT3: 5.7 (1.7-12.7) pmol/L, fT4: 16.2 (9.9-33.5) pmol/L, TSH: 5.4 (0.63-41.8) mU/L, Tg: 171 (15-2124) ng/mL, UIC: 39 (0-90) μg/L, breast milk iodine levels: 47 (10-120) μg/L, thyroid USG: 0.75 (0.35-1.72) mL for the UT group. A significant difference was found between groups in respect to fT3, fT4, TSH and Tg levels. No significant difference in thyroid ultrasonography, UIC, and breast milk iodine levels was found between the two groups. The Tg levels of 50 out of 71 patients were measured, 40 (80%) of whom had Tg levels above the normal range (101 ng/mL).

CONCLUSIONS

In our country, despite the use of iodized salt, congenital hypothyroidism due to ID remains a problem. The Tg level of newborns can be used as a good indicator of ID.

Three-year follow-up of children with abnormal newborn screening results for congenital hypothyroidism

BACKGROUND

To analyze predictive factors suggesting transient congenital hypothyroidism (TCH) compared to permanent congenital hypothyroidism (PCH) or transient thyroid function test (TFT) abnormalities among children who had positive screening results at our centers over the past decade.

METHODS

A retrospective chart review of 105 subjects who presented elevated TSH levels on a newborn screening test (NST) was done. TCH was defined when a trial-off therapy was successful, and PCH was defined when a trial failed or when the subject was kept on medication beyond 3 years of age. A transient TFT abnormality was defined when follow-up TFTs were normalized without levothyroxine (LT4) therapy.

RESULTS

Congenital hypothyroidism (CH) was diagnosed in 75.2% (TCH 35.2% and PCH 40.0%) of all subjects; the others (24.8%) showed transient TFT abnormalities. Initial NST-TSH levels (optimal cutoff point, 31.0 μIU/mL), the LT4 dose at 2 years of age (4.1 μg/kg/day), and the maximal LT4 dose (50 μg/day) merged as significant predictive factors discriminating between TCH and PCH. The initial serum level of free T4 (1.06 ng/dL) and not TSH (27.2 μIU/mL) was the only discriminating factor between transient TFT abnormalities and TCH.

CONCLUSION

Earlier re-evaluation might be possible when a patient's initial NST-TSH levels and maximal or 2-year LT4 doses are low, as both are important predictors of successful trial-off therapy in CH patients. When the initial serum level of free T4 is above the average value in neonates with mildly elevated TSH levels, TFTs may be more likely to normalize on their own.

Permanent and Transient Congenital Hypothyroidism in Hamadan West Province of Iran

BACKGROUND

Primary congenital hypothyroidism (CH) is the most common treatable cause of mental retardation and can be classified into permanent and transient types. The purpose of this study was to determine the prevalence of permanent and transient congenital hypothyroidism (CH) in Hamadan, West province of Iran.

METHODS

The study population included all cases with primary congenital hypothyroidism, which were confirmed by thyroid function tests (TSH levels ≥ 10 mIU/L). All these patients had been followed up at the outpatient pediatric endocrine clinic of Besat hospital (Hamadan, Iran) for a period of time between May 2006 and March 2013. Biochemical findings at diagnosis and detailed medical records were collected. Patients were considered as permanent hypothyroidism if their TSH level was 10 (mIU/l) during 6 - 12 months of treatment. Also three years old patients with TSH level > 10 mU/L during one or three months after discontinuation of levothyroxine treatment were considered as permanent hypothyroidism.

RESULTS

A total of 164 children (49.9% male and 50.6% female) diagnosed with CH completed the study. Female/male ratio was 1.02/1. The incidence of CH was about 1/1250 in Hamadan, West province of Iran. Of the 164 patients, 105 cases (64 %) were diagnosed as permanent CH and other 59 cases (36%) were proven to have transient hypothyroidism. Female to male ratio was 1.14 in patients suffering from permanent CH and 0.8 in patients with transient CH. The initial TSH level was found to be significantly higher in cases with permanent CH compared to the patients with transient CH (P = 0.001). Mean TSH level during the first year of treatment was higher in permanent CH cases compared to transient cases (P = 0.001). Children with transient CH had a lower TSH serum level during the three years of treatment (P = 0.000). A significant statistical difference was not found between the genders and permanent or transient CH (P = 0.352). Co-occurring congenital anomalies and birth order were significantly different between two groups (P = 0.028 and P = 0.024, respectively).

CONCLUSIONS

Our regional follow-up data showed that about 40% of newborns with primary CH had transient thyroid dysfunction. Our results further clarify our previous research by providing evidences on the incidence rate of CH. The incidence rates of CH as well as transient type of CH in our region were higher than those reported by other studies which have been conducted in other regions of the world. The initial TSH level was the strongest predictor of treatment cessation. Given the high incidence of transient CH in our region, further studies are needed to confirm the etiology and to provide considerable insight into preventive and/or the treatment strategies.

Biochemical, radiological, and genetic characterization of congenital hypothyroidism in Abu Dhabi, United Arab Emirates

BACKGROUND

Congenital hypothyroidism (CH) is caused by thyroid gland (TG) dysgenesis or inadequate thyroid hormone biosynthesis in a structurally normal gland. Different etiologies are known to be associated with various clinical, biochemical and imaging markers and a subset of cases have an underlying genetic basis. Despite the presence of neonatal screening programs in the UAE, there is a lack of data on the disease etiology in the area. We aim to study the etiology of CH in our center and examine its relationship with the clinical, biochemical, genetic and radiological features.

METHODS

Patients with CH who were followed in our center between 2011 and 2014 are enrolled in the study. Data collected included gender, gestational age, history of CH in a first-degree relative, initial thyroid stimulating hormone (TSH) and thyroxine (T4) levels, imaging findings, associated disease/malformation and treatment details. Selected patients with associated systemic disease or familial CH underwent genetic testing.

RESULTS

Sixty-five patients were enrolled. Ten patients underwent genetic study: seven patients with associated congenital disease/malformation, one with a sibling and two with cousins with CH. Forty-nine subjects had technetium99 and/or ultrasound scans. Dyshormonogenesis was diagnosed in two-thirds of the patients. Three patients of 10 tested had likely causative genetic mutations; two homozygous thyroid peroxidase (TPO) and one heterozygous thyroid stimulating hormone receptor (TSHR) missense mutations.

CONCLUSIONS

Dyshormonogenesis is the commonest etiology in CH in the studied group. It is expected that genetic mutations are more prevalent in our region due to the nature of the CH etiology and the rate of high consanguinity rate.

Incidence and Interrelated Factors in Patients With Congenital Hypothyroidism as Detected by Newborn Screening in Guangxi, China

Background. A newborn screening program (NSP) for congenital hypothyroidism (CH) was carried out in Guangxi in order to understand the incidence of CH and the factors interrelated to major types of CH in this region of China. Methods. During 2009 to 2013, data from 930 612 newborns attending NSP in Guangxi were collected. Patients were classified with either permanent CH (PCH) or transient CH (TCH) after 2 years of progressive study. Results. A total of 1210 patients were confirmed with CH with an incidence of 1/769, including 68 PCH and 126 TCH cases with incidences of 1/6673 and 1/3385, respectively. The frequency of thyroid stimulating hormone values greater than 5 mIU/L was 7.2%, which, based on WHO guidelines, suggests that the population was mildly iodine deficient. Conclusions. The incidence of CH was high in Guangxi. Approximately two thirds of CH patients were TCH, which may be due to a deficiency in iodine within the population.

Agenesis and not ectopia is common in North Indian children with thyroid dysgenesis

CONTEXT

Ectopic Thyroid Gland (ETG) is known to be the most common form of thyroid dysgenesis in children with permanent congenital hypothyroidism (CH). Recent reports indicate that agenesis or hypoplasia of thyroid gland may be commoner as compared to ETG in thyroid dysgenesis (TD). There is limited information available on the proportion of different variants of TD in Indian children.

AIM

To characterize the different TD variants in a cohort of North Indian children with TD.

SETTINGS AND DESIGN

Endocrinology Unit of a large Multispecialty Pediatrics Center located in North India. Retrospective review of clinical records of children with CH due to TD diagnosed between April 2004 and March 2014.

RESULTS

Diagnoses of TD in 94 children (48 boys and 46 girls) were based on combined scanning with high-resolution ultrasonography, and technetium-99m pertechnetate thyroid scintigraphy. Thyroid agenesis, ectopia and hypoplasia were diagnosed in 74 (78.7%), 14 (14.8%) and 6 (6.4%) patients respectively. The mean initial serum total T4 and thyroid stimulating hormone concentrations at diagnosis were 3.03 ± 2.88 μg/dL (range 0.01-8.9) and 284.52 ± 300.67 mIU/L (range 10.03-1159.0) respectively. Patients with ETG were older at the time of diagnosis as compared to patients with hypoplasia or ectopia. The mean duration of follow-up was 3.7 ± 2.85 years (range 3 months-10 years).

CONCLUSIONS

Thyroid agenesis was the most common form of TD in our children with permanent CH. Hypoplasia and ectopia were uncommon. Female preponderance, noted in many previous reports, was not seen in our patients with TD.

Congenital hypothyroidism and the importance of universal newborn screening

Congenital hypothyroidism (CH) is one of the most common preventable causes of mental retardation in children. Early diagnosis and treatment prevent the devastating outcome of mental retardation. Clinical features of CH are subtle and are not evident early in the neonatal period. Therefore, universal newborn screening (NS) is effective in detecting CH and implementing early treatment. This article reviews the current literature regarding the epidemiology, etiology, classification, clinical features, diagnosis of primary CH, and the management of abnormal newborn screen as well as treatment and prognosis of primary CH and outlines the importance of universal newborn screening in preventing mental retardation.