Congenital hypothyroidism in Western Australia 1981-1998

Quality of life and socioeconomic and educational status in patients with congenital hypothyroidism

BACKGROUND

The aim of this study was to investigate the influence of primary congenital hypothyroidism (CH) on quality of life, level of education and socioeconomic status (SES).

METHODS

Two independent study cohorts, a national and a regional, were collected from Finnish national registers and patient records. Data on social security benefits, SES, marital status, and education were collected from Statistics Finland. Health-related quality of life (HRQoL) was studied in the regional patient cohort with the standardized 15D and 16D instruments.

RESULTS

There were no statistically significant differences in education level, marital status, or SES between CH patients (n = 40) and their matched controls at the age of 25 years. The mean 15D score was both statistically significantly and clinically importantly lower in CH patients (n = 29) than controls (0.904 vs. 0.953, p = 0.008). CH patients reported significantly lower scores across various dimensions of physical and mental HRQoL, including breathing, sleeping, speech, excretion, mental function, distress, and vitality. The mean 16D score was lower in CH patients compared to controls (0.917, vs. 0.947), but without statistical significance.

CONCLUSION

SES of CH patients did not differ from matched controls. Thus, most CH patients integrate well into society, but their HRQoL is impaired.

IMPACT

Most patients with primary congenital hypothyroidism integrate well into society. In the current study, their socioeconomic and marital status did not differ from matched controls at the age of 25 years. However, health-related quality of life measured using 15D instrument was impaired. Every fourth patient reported that congenital hypothyroidism influenced everyday life.

Comorbidity in Congenital Hypothyroidism-A Nationwide, Population-based Cohort Study

CONTEXT

Patients with congenital hypothyroidism (CH) are affected more often than the general population by other chronic diseases and neurological difficulties.

OBJECTIVE

The aim of this nationwide population-based register study was to investigate the incidence of congenital malformations, comorbidities, and the use of prescribed drugs in patients with primary CH.

METHODS

The study cohort and matched controls were identified from national population-based registers in Finland. All diagnoses from birth until the end of 2018 were collected from the Care Register, and subject-specific prescription drug purchases were identified from The Prescription Register from birth until the end of 2017.

RESULTS

Diagnoses of neonatal and chronic diseases were collected for 438 full-term patients and 835 controls (median follow-up time 11.6 years; range, 0-23 years). Newborns with CH were more often found to have neonatal jaundice (11.2% and 2.0%; P < .001), hypoglycemia (8.9% and 2.8%; P < .001), metabolic acidemia (3.2% and 1.1%; P = .007), and respiratory distress (3.9% and 1.3%; P < .003) as compared to their matched controls.Congenital malformations were diagnosed in 66 of 438 (15.1%) CH patients and in 62 of 835 (7.4%) controls (P < .001). The most commonly affected extrathyroidal systems were the circulatory and musculoskeletal systems. The cumulative incidence of hearing loss and specific developmental disorders was higher among CH patients than controls. The use of antidepressant and antipsychotic drugs was similar in CH patients and their controls.

CONCLUSION

CH patients have more neonatal morbidity and congenital malformations than their matched controls. The cumulative incidence of neurological disorders is higher in CH patients. However, our results do not support the existence of severe psychiatric comorbidity.

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.

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

OBJECTIVE

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.

DESIGN

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.

RESULTS

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 versus 71 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.

CONCLUSION

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.

Incidence of primary congenital hypothyroidism over 24 years in Finland

BACKGROUND

A rise in the incidence of congenital hypothyroidism (CH) has been reported worldwide. This nationwide study aimed to describe the secular trends and current incidence of CH in Finland.

METHODS

Two independent study cohorts, a national and a regional, were collected from national registers and patient records. The national cohort represents all CH cases born in Finland between 1994 and 2017. Birth data, results of the screening test, and the incidence of CH were reviewed.

RESULTS

Between 1994 and 2017, 1,400,028 children were born in Finland. Of these children, 503 were diagnosed with primary CH (incidence 1:2783). Male-to-female sex ratio was 1:2.0. The nationwide incidence was 33 cases per 100,000 live births between 1994 and 1999, 38 cases per 100,000 live births between 2000 and 2005, 40 cases per 100,000 live births between 2006 and 2011, and 33 cases per 100,000 live births between 2012 and 2017. In the regional cohort (n = 139), the incidence of transient CH was 3.6%. The incidence of mild, moderate, and severe CH remained constant.

CONCLUSIONS

In Finland, the incidence of CH has not changed during the 24-year study period.

IMPACT

As opposed to recent reports worldwide, the incidence of congenital hypothyroidism has not changed between 1994 and 2017 in Finland. The proportions of mild, moderate, and severe congenital hypothyroidism did not change significantly over the study period. Lowering the TSH cut-off limit or increasing immigration did not affect the incidence rate of primary congenital hypothyroidism in Finland.

Infants Diagnosed with Athyreosis on Scintigraphy May Have a Gland Present on Ultrasound and Have Transient Congenital Hypothyroidism

Scintigraphy using technetium-99m (99mTc) is the gold standard for imaging the thyroid gland in infants with congenital hypothyroidism (CHT) and is the most reliable method of diagnosing an ectopic thyroid gland. One of the limitations of scintigraphy is the possibility that no uptake is detected despite the presence of thyroid tissue, leading to the spurious diagnosis of athyreosis. Thyroid ultrasound is a useful adjunct to detect thyroid tissue in the absence of 99mTc uptake.

AIMS

We aimed to describe the incidence of sonographically detectable in situ thyroid glands in infants scintigraphically diagnosed with athyreosis using 99mTc and to describe the clinical characteristics and natural history in these infants.

METHODS

The newborn screening records of all infants diagnosed with CHT between 2007 and 2016 were reviewed. Those diagnosed with CHT and athyreosis confirmed on scintigraphy were invited to attend a thyroid ultrasound.

RESULTS

Of the 488 infants diagnosed with CHT during the study period, 18/73 (24.6%) infants with absent uptake on scintigraphy had thyroid tissue visualised on ultrasound (3 hypoplastic thyroid glands and 15 eutopic glands). The median serum thyroid-stimulating hormone (TSH) concentration at diagnosis was significantly lower than that in infants with confirmed athyreosis (no gland on ultrasound and no uptake on scintigraphy) (74 vs. 270 mU/L), and median free T4 concentration at diagnosis was higher (11.9 vs. 3.9 pmol/L). Six of 10 (60%) infants with no uptake on scintigraphy but a eutopic gland on ultrasound had transient CHT.

CONCLUSION

Absent uptake on scintigraphy in infants with CHT does not rule out a eutopic gland, especially in infants with less elevated TSH concentrations. Clinically, adding thyroid ultrasound to the diagnostic evaluation of infants who have athyreosis on scintigraphy may avoid committing some infants with presumed athyreosis to lifelong levothyroxine treatment.

Development of a risk prediction model for early discrimination between permanent and transient congenital hypothyroidism

OBJECTIVE

To develop a risk prediction model for early discrimination between transient and permanent congenital hypothyroidism (CH).

DESIGN AND SETTING

In a retrospective cohort, 1047 confirmed CH neonates, from 15 randomly selected provinces in Iran, were entered to the study. Clinical and biochemical information of transient and permanent cases, distinct at the age of 3 years were retrospectively gathered.

RESULTS

Among CH neonates, the overall prevalence of permanent CH was 57.1%. Using forward stepwise multivariable logistic regression analysis, confirmatory venous TSH, total T4 < 8.2 ng/dl, requiring levothyroxine dosage increase, venous TSH ≥ 10 mU/l between 6 and 12 months of age, parental consanguinity and family history of thyroid diseases were associated with increased risk of permanent CH. The prediction model achieved a very good power in discriminating patients with transient and permanent CH with an optimism-corrected area under the ROC curve of 0.86 (95% CI:0.84-0.88) with a very good calibration. Integrated discrimination improvement (IDI) test indicated significantly greater diagnostic performance of the model compared to serum TSH alone.

CONCLUSIONS

Using several potential predictors for permanent CH, we developed a relatively powerful risk prediction model as a cost-saving screening tool in order to avoid unnecessary long-term treatment of transient cases which might empower clinicians for prognostication of the CH course and tailoring treatment up to 1 year of age.

Risk factors for transient and permanent congenital hypothyroidism: a population-based case-control study

Background

Congenital hypothyroidism (CH) is the most important cause of mental and physical retardation in newborns. The prevalence of CH has been reported high in East Azerbaijan province of Iran. However, the risk factors for CH are poorly understood. This study aimed to determine and compare risk factors for permanent and transient CH in East Azerbaijan, Iran.

Methods

A case-control study was conducted in the Iranian national screening program for CH. This study included 680 neonates: 340 neonates with confirmed CH and 340 matched healthy controls born at the same period and from the same residential area as the cases. Multiple logistic regression analyses were used to estimate the crude and adjusted odds ratios and 95% confidence intervals for the association between different risk factors and transient and permanent CH.

Results

Out of the 680 participants, 364 (53.53%) were male. Family history of CH (OR = 5.09, 95% CI: 1.66–15.63), neonatal jaundice (OR = 3.89, 95% CI: 2.36–6.43) and parental consanguineous relation (OR = 2.19, 95% CI: 1.51–3.17) were associated with an increased risk of permanent CH. Likewise, the use of Betadine in pregnancy (OR = 4.87, 95% CI: 1.45–16.28), family history of CH (OR = 5.98, 95% CI: 2.04–17.48), neonatal jaundice (OR = 2.81, 95% CI: 1.75–4.52), parental consanguineous relation (OR = 3.86, 95% CI: 1.92–5.74), and gestational age at birth (OR = 3.2, 95% CI: 1.90–5.41) were identified as risk factors for transient CH.

Conclusion

Family history, neonatal jaundice, gestational age at birth, and Betadine usage in pregnancy are associated with CH.

[Risk factors for neonatal congenital hypothyroidism: a Meta analysis]

OBJECTIVE

To investigate the risk factors for congenital hypothyroidism (CH) in neonates, and to provide a reference for the prevention of CH.

METHODS

The databases including China Biomedical Literature Service System, China National Knowledge Infrastructure, Wanfang Data, and Weipu Periodical Database, PubMed, Web of Science, Embase, SpringerLink, and Elsevier/ScienceDirect were searched for studies on the risk factors for CH in neonates published up to August 1, 2020. R 3.6.2 and RevMan 5.3 software were used to perform a Meta analysis.

RESULTS

A total of 20 studies were included, with 13 case-control studies and 7 cross-sectional studies. There were 11 564 neonates in total, with 3 579 neonates in the case group and 7 985 neonates in the control group. The Meta analysis showed that advanced maternal age (OR=2.111, 95%CI: 1.275-3.493), thyroid disease during pregnancy (OR=3.365, 95%CI: 1.743-6.500), gestational diabetes mellitus (OR=2.158, 95%CI: 1.545-3.015), anxiety (OR=3.375, 95%CI: 2.133-5.340), medication during pregnancy (OR=2.774, 95%CI: 1.344-5.725), radiation exposure during pregnancy (OR=3.262, 95%CI: 1.950-5.455), family history of thyroid disease (OR=8.706, 95%CI: 5.991-12.653), low birth weight (OR=2.674, 95%CI: 1.895-3.772), fetal macrosomia (OR=1.657, 95%CI: 1.187-2.315), preterm birth (OR=2.567, 95%CI: 2.070-3.183), post-term birth (OR=2.083, 95%CI: 1.404-3.091), twin pregnancy or multiple birth (OR=3.455, 95%CI: 1.958-6.096), and birth defects (OR=6.038, 95%CI: 3.827-9.525) were risk factors for CH in neonates.

CONCLUSIONS

Advanced maternal age, gestational thyroid disease, gestational diabetes mellitus, anxiety, medication during pregnancy, radiation exposure during pregnancy, family history of thyroid disease, low birth weight, fetal macrosomia, preterm birth, post-term birth, twin pregnancy or multiple pregnancy, and birth defects may increase the risk of CH in neonates.

Genotype and phenotype correlation in a cohort of Chinese congenital hypothyroidism patients with DUOX2 mutations

Background

This study aimed to explore the relationship between the phenotype and genotype of congenital hypothyroidism (CH) caused by dual oxidase 2 (DUOX2) mutation in Chinese children, and to investigate the genetic causes of permanent and transient hypothyroidism through next-generation genetic testing technology and long-term clinical follow-up data.

Methods

We recruited 61 patients with thyroid stimulating hormone (TSH) levels of >10 mIU/mL during newborn screening, clinical diagnosis of CH, and L-thyroxine (L-T4) oral treatment within 1 month of birth; they were followed up until the present. All CH infants and their parents were genotyped using whole-exome sequencing (WES); DUOX2 variants were detected in 20 infants, and the longitudinal prognosis, genotype, and phenotype correlations were analyzed.

Results

Biallelic DUOX2 mutations were detected in 20 participants. All of them were born full term. All patients were treated with L-T4 when diagnosed with CH; 9 of them stopped L-T4 eventually before 3 years old; and 2 were treated with a reduced dose of L-T4 (12.5 µg per day). The others were still treated with L-T4 at a dose of 37.5–87.5 µg per day. Of these 20 participants, 5 carried an R1110Q variant and 5 carried K530X variants. A total of 7 novel variants were discovered in our cohort. The variants carried in transient CH patients were located extracellularly and not near the functional domain.

Conclusions

Most CH patients with DUOX2 mutations were those with transient or subclinical CH. The R1110Q, R885L, and K530X were the most common variants in our Chinese cohort. The R1110Q and K530X variants may play a founder effect in the transient CH. The R885L variant may play a benign role in transient CH. Intracellular variants or those near the functional domain may cause permanent CH.

Optimal Timing of Repeat Newborn Screening for Congenital Hypothyroidism in Preterm Infants to Detect Delayed Thyroid-Stimulating Hormone Elevation

OBJECTIVES

To evaluate the timing of a delayed rise in thyroid-stimulating hormone (TSH) levels in preterm infants with congenital hypothyroidism, and to determine whether cases of congenital hypothyroidism would be missed by using current consensus guidelines of repeat screening at approximately 2 weeks of age or 2 weeks after the first screening.

STUDY DESIGN

The study was performed over a 13-year period (January 2004-December 2016). Whole-blood TSH samples were collected between 72 and 120 hours after birth. Repeat samples were collected weekly in preterm infants until the infant was term-corrected (37 weeks' gestation). Patients were followed up to determine whether congenital hypothyroidism was permanent or transient.

RESULTS

Twenty-seven (50.9%) preterm infants born at <33 weeks of gestation who were diagnosed with congenital hypothyroidism had delayed TSH elevation and would not have been detected on first newborn screen. Twelve of these infants (40.7%) with delayed TSH elevation had decompensated hypothyroidism at diagnosis (free thyroxine [FT4] <10 pmol/L), and 4 had severe congenital hypothyroidism (FT4 <5.5 pmol/L) at diagnosis. If screening had been repeated only at 2 weeks of life, 13 infants (48%) with delayed TSH elevation would not have been identified. Of the 27 infants with delayed TSH elevation, 6 (22%) have permanent congenital hypothyroidism, and another 12 will be reevaluated at age 3 years.

CONCLUSION

Repeat screening for congenital hypothyroidism in preterm infants is necessary to avoid missing cases of congenital hypothyroidism with delayed TSH elevation. Repeat screening once at 2 weeks of life will miss infants with delayed TSH elevation and decompensated permanent congenital hypothyroidism.

Incidence of Congenital Hypothyroidism Over 37 Years in Ireland

BACKGROUND AND OBJECTIVES

Congenital hypothyroidism (CHT) is one of the most common preventable causes of learning disability. Newborn screening with whole-blood thyroid-stimulating hormone measurements was introduced in the Republic of Ireland in 1979 and is coordinated from a single center with an unchanged protocol since its inception. Our objective in this study was to describe the incidence of CHT in the Republic of Ireland over the past 37 years in the context of a complete national population and an unchanged screening protocol.

METHODS

The newborn screening records of all individuals who were diagnosed with CHT between 1979 and 2016 were reviewed. Infants with positive screening results had a whole-blood thyroid-stimulating hormone value of ≥15 mU/L at 72 to 120 hours of life; values of 8 to 15 mU/L required a repeat whole-blood screening test.

RESULTS

Of 2 361 174 infants who were screened between July 1979 and December 2016, 1063 (662 girls) were diagnosed with CHT (incidence: 0.45 cases per 1000 live births). The number of detected cases increased from 0.27 cases per 1000 live births treated between 1979 and 1991 to 0.41 cases per 1000 live births treated between 1992 and 2004 to 0.65 cases per 1000 live births treated between 2005 and 2016. The increase in detected cases of CHT was predominantly in the normal or hyperplastic gland category.

CONCLUSIONS

The incidence of CHT has increased significantly in the Republic of Ireland over the past 37 years despite a consistent screening cutoff. The increased rate was not explained by an increased survival rate of preterm infants or a changing population heterogeneity.

Incidence of congenital hypothyroidism in China: data from the national newborn screening program, 2013-2015

BACKGROUND

Congenital hypothyroidism (CH) is one of the most frequent, preventable causes of mental retardation. Little has been reported on the epidemiological characteristics of CH in China. We aimed to estimate the incidence of CH in China and investigate its geographical variation.

METHODS

We analyzed data from the nationwide newborn screening program for CH between 2013 and 2015. Poisson regression was used to generate the odds ratios (ORs) and 95% confidence intervals (CIs) between the rates of CH and selected demographic characteristics and assess the potential association between CH incidence and geographical locations.

RESULTS

A total of 18,666 patients with CH were identified from 45.2 million newborns, yielding an overall incidence rate of 4.13 per 10,000 live births. Compared with those in the remote area, regardless of infant sex, a higher incidence risk for CH was present in newborns in coastal areas and inland areas (females: OR=2.00, 95% CI: 1.86-2.16 and OR=1.74, 95% CI: 1.61-1.87, respectively; males: OR=1.70, 95% CI: 1.59-1.83 and OR=1.52, 95% CI: 1.42-1.63, respectively). Additionally, the highest risk of CH for thyroid-stimulating hormone (TSH) screening values <40 mU/L was observed among neonates in the coastal areas, while TSH screening values of 70-100 mU/L were observed among those in the inland areas.

CONCLUSIONS

The overall incidence of CH is high in China. The significant geographical variations of CH incidence are presented in this study.

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.

Worldwide Recall Rate in Newborn Screening Programs for Congenital Hypothyroidism

CONTEXT

Neonatal mass screening program for congenital hypothyroidism provides the best tool for prevention of its devastating effects on mental development. Despite the overall success of the screening programs in detecting congenital hypothyroidism and eliminating its sequelae and new developments made in the program design, high recall rate and false positive results impose a great challenge worldwide. Lower recall rate and false positive results may properly organize project expenses by reducing the unnecessary repeated laboratory tests, increase physicians and parents' assurance and cooperation, as well as reduce the psychological effects in families.

EVIDENCE ACQUISITION

In this review, we assessed the recall rate in different programs and its risk factors worldwide.

METHODS

Publications reporting the results of the CH screening program from 1997 to 2016 focusing on the recall rate have been searched.

RESULTS

Recall rates vary from 0.01% to 13.3% in different programs; this wide range may be due to different protocols of screening (use of T4 or TSH or both), different laboratory techniques, site of sample collection, recall cutoff, iodine status, human error, and even CH incidence as affected by social, cultural, and regional factors of the population.

CONCLUSIONS

It is suggested to implement suitable interventions to reduce the contributing factors by improving the quality of laboratory tests, selecting conservative cut off points, control iodine deficiency, use of iodine free antiseptic during delivery, and use of more specific markers or molecular tests. Applying an age dependent criteria for thyrotropin levels can be helpful in regions with a varied time of discharge after delivery or for preterm babies.

DUOX2 Mutations Are Frequently Associated With Congenital Hypothyroidism in the Korean Population

Background

Most cases with congenital hypothyroidism (CH) are usually sporadic, while about 20% of the cases are caused by genetic defects. Little information is available regarding the mutation incidence and genetic heterogeneity of CH in Koreans. We aimed to determine the mutation incidence of CH in newborn screenings (NBS) and to evaluate the frequency and spectrum of mutations underlying CH.

Methods

A total of 112 newborns with thyroid dysfunction were enrolled from 256,624 consecutive NBS. Furthermore, 58 outpatients with primary CH were added from an endocrine clinic. All coding exons of TSHR, PAX8, TPO, DUOX2, DUOXA2, and SCL5A5 were sequenced.

Results

The mutation incidence of CH was estimated to be 1 in 6,580 newborns. A total of 36 different mutations were identified in 53 cases. The overall mutation positive rate was 31%. The DUOX2 mutations were the most prevalent in both newborns and outpatients. Seven different recurrent mutations [p.G488R (n=13), p.A649E (n=3), p.R885Q (n=3), p.I1080T (n=2), and p.A1206T (n=2) in DUOX2; p.Y138X (n=9) in DUOXA2; and p.R450H (n=5) in TSHR) were identified as the mutations underlying CH.

Conclusions

The mutation incidence of CH was considerably higher than expected in the Korean newborn population. This study revealed seven different recurrent mutations underlying CH. We conclude that DUOX2 mutations are a frequent cause of CH in the Korean population.

Feasibility of an Early Discontinuation of Thyroid Hormone Treatment in Very-Low-Birth-Weight Infants at Risk for Transient or Permanent Congenital Hypothyroidism

BACKGROUND/AIMS

This prospective study was conducted to investigate the feasibility of an early discontinuation of thyroid hormone treatment in very-low-birth-weight (VLBW) infants with congenital hypothyroidism (CH).

METHODS

We enrolled VLBW infants between January 2011 and December 2012. The infants were divided into the hypothyroid and normal thyroid function groups according to the results of a thyroid function test. We performed an early off-therapy trial at 24 months of age.

RESULTS

Of the 182 VLBW infants enrolled, 15 were lost to follow-up and 167 were finally enrolled. In total, 24 infants (14.4%) were assigned to the hypothyroid function group and were treated with thyroid hormone. Younger gestational age and a lower birth weight were associated with hypothyroid function. In the hypothyroid function group, hypothyroidism (HT) and hyperthyrotropinemia (HTT) were observed in 13 and 11 infants, respectively. There were no differences in the clinical characteristics between the HT and HTT groups. Overall, 24 infants discontinued thyroxine medication at 24 months of age after normal results had been confirmed by radiologic work-ups, including thyroid ultrasonography and technetium-99m scans. All infants were successfully weaned off thyroxine and maintained euthyroid function.

CONCLUSION

Early discontinuation of thyroid hormone replacement therapy is possible in the majority of VLBW infants with CH.

Can One Predict Resolution of Neonatal Hyperthyrotropinemia?

OBJECTIVE

To identify predictors of transience vs permanence of neonatal hyperthyrotropinemia. We hypothesized that infants with greater severity of perinatal stress are more likely to have transient thyrotropin elevations.

STUDY DESIGN

We retrospectively studied infants diagnosed with hyperthyrotropinemia between 2002 and 2014, following them for up to 12 years after diagnosis. Patients were divided into 3 groups: transient hyperthyrotropinemia (treatment was never prescribed), transient congenital hypothyroidism (treatment started but discontinued), and permanent congenital hypothyroidism (withdrawal unsuccessful or not attempted). We performed univariate and multiple logistic regression analyses, including and excluding infants with maternal thyroid disease.

RESULTS

We included 76 infants, gestational age mean (±SD) 34.2 (±5.7) weeks, evaluated for hyperthyrotropinemia. Thirty-five (46%) were never treated, and 41 (54%) received levothyroxine. Of the treated patients, 16 successfully discontinued levothyroxine, and for 25 withdrawal either failed or was not attempted. We found that male patients were almost 5 times more likely than female patients to have transient neonatal hyperthyrotropinemia (OR 4.85; 95% CI 1.53-15.37). We documented greater maternal age (31.5 ± 5.48 years vs 26 ± 6.76 years, mean ± SD, P = .02), greater rate of cesarean delivery (86.7% vs 54.2%; P = .036), and retinopathy of prematurity (37.5% vs 8%; P = .02) in the group with transient congenital hypothyroidism vs the group with permanent congenital hypothyroidism.

CONCLUSION

The results show transience of neonatal thyrotropin elevations in a majority of patients and suggest a possible association of hyperthyrotropinemia with maternal and perinatal risk factors.

Changes in the incidence and etiology of congenital hypothyroidism detected during 30 years of a screening program in central Serbia

Congenital hypothyroidism (CH) is the most frequent congenital endocrine disorder. The purpose of the present study was to determine the incidence of CH in Central Serbia from 1983 to 2013. Newborn screening for CH was based on measuring neonatal thyroid-stimulating hormone (TSH) using a 30 mU/l cutoff (CO) until 12/1987 (P1), 15 mU/l until 12/1997 (P2), 10 mU/l until 12/2006 (P3), and 9 mU/l thereafter (P4). During the study period, there were 1,547,122 live births screened for CH. Primary CH was detected in 434 newborns, with incidence of 1:3728. With gradual lowering of the CO, the incidences of CH increased from 1:5943 in P1 to 1:1872 in P4 (p < 0.001). Incidence of CH with ectopic and enlarged gland doubled (p < 0.001), while prevalence of athyreosis remained relatively constant. The most prominent finding was the increase in the transient CH from none in P1 to 35 % of all CH patients in P4.

CONCLUSION

The overall incidence of CH in Central Serbia during study period nearly tripled, with a significant increase in almost all etiological categories, and was associated with lowering TSH cutoffs as well as other yet unidentified factors. Further studies are needed to identify other factors associated with increasing incidence of CH.

WHAT IS KNOWN

Congenital hypothyroidism (CH) is the main cause of preventable mental retardation. Recent reports have indicated a progressive increase in the incidence of primary CH throughout the world, partially explained by lowering of the TSH cutoff values.

WHAT IS NEW

During the study period associated with lowering of the TSH cutoffs, the overall incidence of CH in Serbia tripled, including transient CH, ectopy, and dyshormonogenesis, while prevalence of athyreosis remained stable during 30 years. Significant increase in the incidence of both permanent and transient CH was observed, associated with lowering of TSH cutoffs as well as other yet unidentified factors.

Multiple factors influencing the incidence of congenital hypothyroidism detected by neonatal screening

BACKGROUND/AIMS

Over the years a rise in the incidence of congenital hypothyroidism (CH) has been described worldwide. The aim of our study was to investigate trends in the incidence of CH in Italy over the period 1987-2008, and to investigate which factors may have influenced the CH incidence in our country.

METHODS

Data were derived from the Italian National Registry of Infants with Congenital Hypothyroidism. Since 1998 the laboratory procedures related to neonatal screening for CH have changed drastically. Accordingly, we estimated the CH incidence during the period 1987-1998 (period 1) and the period 1999-2008 (period 2).

RESULTS

The incidence of CH confirmed at birth (including transient hypothyroidism) has increased from 1:3,000 liveborn infants in period 1 to 1:1,940 in period 2 (+54%), whereas the incidence of purely permanent CH increased from 1:3,200 to 1:2,320 (+38%). Lowering of the TSH cutoff was the most important factor contributing to the increase of CH incidence in Italy. Moreover, an increment of 58% of preterm babies with permanent CH was found in period 2 compared with period 1.

CONCLUSION

Our results suggest that more than one cause is responsible for the rise in the increasing CH incidence, with lowering of the screening TSH cutoff and an increased survival rate of a growing number of preterm babies both playing an important role.

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

AIM

Studies examining the relationship between maternal and infant thyroid parameters have shown conflicting results. Record linkage provides an opportunity to examine the association between maternal and infant thyroid-stimulating hormone (TSH) levels. Our aim was to demonstrate the feasibility of record linkage of newborn screening (NBS), laboratory and birth databases for research by investigating the association between maternal and newborn TSH levels.

METHODS

The records of 2802 women with first trimester serum TSH concentrations were linked with population-based birth data and NBS data containing infant TSH levels. Association between moderately high neonatal TSH levels (>5 mIU/L) and maternal and infant characteristics was evaluated. The correlation and association between maternal and infant TSH levels were assessed using Pearson's correlation coefficient and multivariable linear regression, respectively.

RESULTS

Of maternal and birth records, 99.3% linked with an NBS record. Mother's country of birth, gestational age (>41 weeks) and lower birthweight were associated with neonatal TSH levels >5 mIU/L. Neonatal and maternal first trimester TSH levels were not correlated, although statistically significant (r = 0.05, P = 0.008). The association between neonatal TSH and maternal TSH, after adjusting for maternal age, gestational age and age at NBS testing, was also small (b = 0.039, P = 0.009).

CONCLUSIONS

Record linkage is a feasible and cost-efficient way to investigate the association between maternal factors and neonatal hormone levels. First trimester maternal thyroid levels are not correlated with neonatal TSH levels. This method of outcome assessment can be used for future research examining long-term outcomes for infants with different NBS results.

Screening for congenital hypothyroidism: a worldwide view of strategies

Detection by newborn screening (NBS) and treatment of babies with congenital hypothyroidism (CH) has largely eliminated the intellectual disability caused by this disorder. Lowering of the screening TSH cutoff and changes in birth demographics have been associated with an approximate doubling of the incidence of CH, from 1:3500 to 1:1714. The additional cases detected by lowering of the TSH cutoff tend to have milder hypothyroidism, with imaging often demonstrating a eutopic, "gland in-situ", and some cases turn out to have transient CH. Based on our search for current screening programs, approximately 71 percent of babies worldwide are not born in an area with an established NBS program, despite the existence of screening for over five decades in developed countries. Thus, the majority of babies with CH worldwide are not detected and treated early, such that the economic burden of retardation owing to CH remains a significant public health challenge.

Changing perspectives in screening for congenital hypothyroidism and congenital adrenal hyperplasia

PURPOSE OF REVIEW

The purpose of this review is to summarize recent information that has had a significant impact on the laboratory diagnosis and clinical management of newborns with congenital hypothyroidism and congenital adrenal hyperplasia (CAH).

RECENT FINDINGS

An approximate doubling of the incidence rate of congenital hypothyroidism in many parts of the world has been attributed to increased detection of infants with mild disease, delayed thyroid stimulating hormone elevations and demographic changes. A substantial number of children with modest thyroid stimulating hormone elevations on screening have permanent disease. Circulating levels of thyroxine may vary among hypothyroid children who are given identical dosages of medication. Treated infants should be monitored every 1-2 months during the first year of life. Although, generic and brand name thyroxine preparations may not be bioequivalent, children can be well controlled on generic formulations.Enzyme linked immunoassay assay for 17-hydroxyprogesterone is associated with a high rate of false positive specimens. In attempts to minimize this problem, some programs have resorted to two-tier screening of the initial specimen with steroid profiling as the second tier. Several programs are routinely testing second specimens in an effort to reduce the incidence of missed CAH cases.

SUMMARY

This review explains the uptick in incidence rate of congenital hypothyroidism and underscores issues in management that can affect developmental outcome. One specimen two-tier testing for CAH resulted in an increased false negative rate without significantly reducing the false positive rate. The benefit of collecting second specimens for CAH screening is problematic. Optimal treatment of CAH continues to pose a challenge.

Mild neonatal hyperthyrotrophinaemia: 10-year experience suggests the condition is increasingly common but often transient

OBJECTIVE

To examine a large population of infants with mild neonatal hyperthyrotrophinaemia (MNH) and determine prevalence, clinical characteristics and treatment history.

METHODS

Retrospective study of infants with MNH followed at The Hospital for Sick Children between 2000 and 2011. MNH was defined by an abnormal newborn screen followed by thyroid-stimulating hormone (TSH) between 5 and 30 mU/l and normal free T4 (FT4) on confirmatory tests.

RESULTS

Mild neonatal hyperthyrotrophinaemia represented 22·3% of patients (103/462; 60 boys, 43 girls) within our clinic. Incidence increased from two of 20 in 2000 to 31 of 74 cases in 2010. Seventy eight percent of patients started L-thyroxine (initial dose: 8·3 ± 2·5 mcg/kg). The treated group had higher confirmatory TSH levels (P = 0·001) and had undergone thyroid scintigraphy more often (P = 0·0001) compared with the nontreated group. Evidence of overtreatment was detected in 45% of thyroid function tests obtained during treatment. Among the treated infants who had reached 3 years of age, 45% (N = 14) underwent a trial-off medication. Compared with those not trialled-off therapy, these infants were less likely to have had dose escalations during treatment (P = 0·001). The trial-off treatment was successful in 50% of cases. In the subset of infants with confirmatory TSH >10 mU/l, trial-off therapy was successful in 40%. None of the assessed variables predicted success of trial-off therapy.

CONCLUSIONS

Mild neonatal hyperthyrotrophinaemia is an increasingly common diagnosis. It is more common in males and is often transient, but predictors of success of trial-off therapy were not identified. Further studies are needed to determine optimum L-thyroxine dosing and to determine whether treatment improves neurocognitive outcomes.

Risk factors for congenital hypothyroidism in Egypt: results of a population case-control study (2003-2010)

BACKGROUND AND OBJECTIVES

Although the prevention of the neuropsychological consequences of congenital hypothyroidism (CH) through the use of replacement therapy represents an important public health success, knowledge about the modifiable risk factors could reduce the number of infants affected by this disease. This study was carried out to identify risk factors for CH at Fayoum Governorate, Egypt.

DESIGN AND SETTINGS

This was a population-based case-control study, which started in 2003 and was carried out for 8 years through Fayoum center of the Egyptian Ministry of Health and Population screening program for CH.

METHODS

This study was a population-based case-control study carried out by using national project for CH. One control was enrolled for each new CH infant; 320 cases and 320 controls were enrolled in 8 years. Maternal and neonatal influences were investigated.

RESULTS

A statistically significant association of CH was observed with birth defects, female gender, gestational age > 40 weeks, and gestational diabetes. An increased risk for CH was detected in twins by a multivariate analysis.

CONCLUSION

Our results suggest a multifactorial origin of CH in which genetic (high frequency of additional malformations) and environmental factors (especially maternal diabetes) play a role in the development of the disease.

Congenital hypothyroidism after assisted reproductive technology in Japan: comparison between multiples and singletons, 2005-2009

Background

The relationship between congenital hypothyroidism (CH) and multiple pregnancy has not been fully studied in Japan.

Methods

Complete nationwide data of assisted reproductive technology (ART) in Japan from 2005 to 2009 presented by the Japan Society of Obstetrics and Gynecology, which include information on CH and birth defects were used for analyses. Diseases were reclassified according to the International Classification of Diseases, tenth edition (ICD-10, 2003 version). The relative risk (RR) and 95% confidence interval (CI) of the incidence rate for CH was calculated with singletons as the reference group. Additional birth defects with CH were examined. The probandwise concordance rate of multiples and recurrence risk ratio were calculated.

Results

There were 18 patients with CH, consisting of 12 singletons and 6 multiples. The incidence rates of CH per 1,000 live births in singletons and multiples are 0.14 (=12/87,145) and 0.31 (=6/19,533), respectively. The incidence rate was more than twofold higher in multiple births than in singleton births, but the difference was not statistically significant (RR=2.2, 95% CI 0.8–5.9). Additional birth defects were present in three patients with CH (17%=3/18). The multiples were affected by other birth defects more frequently (33%=2/6) than the singletons (8%=1/12). The six multiple-births patients were derived from one concordant twin pair, which consisted of two twin patients; three discordant twin pairs, which consisted of three twin patients; and one discordant triplets set, which consisted of one triplet patient. Thus, the probandwise concordance rate was 33.3% (=2/(2+4)). The estimated recurrence risk ratio was 1976 (for the total ART population) or 609 (for the Japanese general population).

Conclusions

CH was more frequent in multiples compared to singletons. A higher percentage of additional birth defects was also observed in multiples compared to singletons. The familial aggregation of CH was suggested.

Etiology of increasing incidence of congenital hypothyroidism in New Zealand from 1993-2010

BACKGROUND

Recent reports suggest that the incidence of congenital hypothyroidism (CHT) is increasing in some countries. The etiology of this change is unclear, and it may relate to changes in screening thresholds. We aimed to determine whether the incidence of CHT in New Zealand has changed and whether ethnic-specific rates and the rates of CHT subtypes have also changed.

METHODS

The New Zealand neonatal TSH-based screening program has prospectively identified cases of CHT using the same assay and screening thresholds since 1993. Thyroid scintiscans are routinely recommended. We retrospectively identified all cases of CHT requiring levothyroxine treatment from 1993-2010 recorded by the national newborn screening program (>99.5% coverage). Among other parameters, ethnic and CHT subtype-specific incidence rates were calculated.

RESULTS

There were 330 new cases of CHT and 1,053,457 live births registered in New Zealand in the 18-yr period, and 86% of cases had a scintiscan, 67% of which had thyroid dysgenesis (female to male ratio 5.0:1.0) and 33% dyshormonogenesis (0.9:1.0). The overall incidence of CHT rose from 2.6 to 3.6 per 10,000 live births (P < 0.01). The incidence of dyshormonogenesis (P = 0.01) increased but not of dysgenesis (P = 0.13). This was mediated by a 2-fold increase in Asian births and 40% increase in Pacific Island births. Both ethnic groups displayed higher rates of dyshormonogenesis compared with New Zealand Europeans (odds ratio 3.3 and 2.6, respectively). There was no change in the ethnic-specific incidences of CHT.

CONCLUSION

Although the incidence of congenital hypothyroidism in New Zealand has increased, this is due to changes in the country's ethnic composition.

Prevalence of congenital hypothyroidism--current trends and future directions: workshop summary

In response to published newborn-screening data that have shown an increase in the incidence (birth prevalence) rate of primary congenital hypothyroidism (CH) in the United States, a workshop was held in Atlanta, Georgia, on February 27 and 28, 2008, to examine this issue. Topics of the meeting included pathophysiology, medical management, and follow-up of CH; transient hypothyroidism (etiology, clinical implications, management, and changes in prevalence); risk factors for CH; laboratory approaches to newborn screening for CH; state-specific evaluations of trends in incidence rates of CH; and concluding discussions on future directions to resolve outstanding issues. Through presentations and discussion, gaps in knowledge were identified, such as the lack of consistent definitions for CH and transient hypothyroidism and the effects of preventable risk factors on incidence rates of CH. One outcome of the meeting was a series of accompanying articles that examined (1) trends in the incidence rates of CH in individual states and nationally, (2) effects of newborn-screening practices on CH-incidence rates, (3) the contribution of transient hypothyroidism to CH-incidence rates, and (4) future research directions. In this summary, we briefly touch on the topics of these articles and examine highlights of other presentations from the workshop that illuminated the secular trends in reported CH-incidence rates in the United States.

The impact of transient hypothyroidism on the increasing rate of congenital hypothyroidism in the United States

The reported incidence rate of primary congenital hypothyroidism (CH) has been increasing in the United States over the past 2 decades. We have considered the possibility that the inclusion of cases of transient hypothyroidism has inflated the reported incidence rate of CH. Assessing the effects of cases of transient hypothyroidism on the incidence rate is problematic, because the definitions, diagnostic criteria, and differentiation from transient hyperthyrotropinemia vary widely among state newborn screening programs. Among the 4 etiologies for transient hypothyroidism (maternal thyrotropin receptor-blocking antibodies, exposure to maternal antithyroid medications, iodine deficiency, and iodine excess), there is little evidence of increases in the incidence rate from thyrotropin receptor-blocking antibodies. Exposure to antithyroid drugs could contribute significantly to the incidence rate of transient CH, given the high estimated incidence of active maternal hyperthyroidism. Iodine deficiency or excess in the United States seems unlikely to have contributed significantly to the incidence rate of CH, because the secular trend toward lower iodine intake among women of reproductive age in the 1980s and 1990s seems to have plateaued, and perinatal iodine exposure has presumably declined as a result of recommendations to discontinue using iodine-containing disinfectants. Although the female-to-male sex ratio among newborns with thyroid agenesis or dysgenesis (the most common causes of CH) is typically 2:1, analysis of the sex ratio of newborns diagnosed with presumed CH in the United States suggests that a substantial proportion might have transient hypothyroidism or hyperthyrotropinemia, because the sex ratio has been well below the expected 2:1 ratio. Combined ultrasonography and (123)I scintigraphy of the thyroid gland are effective tools for identifying cases of thyroid agenesis and dysgenesis and can help to differentiate cases of transient hypothyroidism from true CH. Imaging is also a vital component in evaluating children who, at 3 years of age, undergo a trial of discontinuation of levothyroxine treatment to test for persistence of hypothyroidism. Ultimately, thyroid gland imaging, in conjunction with long-term follow-up studies that appropriately assess and report whether there was permanence of hypothyroidism, will be necessary to address the true incidence rate of CH and any contribution to the observed rate by transient cases of hypothyroidism or hyperthyrotropinemia.

Trends in incidence rates of congenital hypothyroidism related to select demographic factors: data from the United States, California, Massachusetts, New York, and Texas

Primary congenital hypothyroidism (CH) is a common and preventable cause of intellectual disability. The incidence rate of CH has been reported to be increasing in the United States, but the factors behind the observed rate increase are not known. We summarize here the data presented at a workshop on CH, at which factors potentially related to the CH-incidence-rate increase (namely, race, ethnicity, sex, and birth outcomes) were evaluated. Data sources for the analyses included a national data set of newborn-screening results and state-specific data from newborn-screening programs in California, Massachusetts, New York, and Texas. The incidence rate of CH increased in the United States by 3% per year; however, an increase did not occur in all states, at a constant rate, or even at the same rate. Analysis of US data (1991-2000) showed a CH-incidence-rate increase only among white newborns. More recently, in California (2000-2007), the rate was constant in non-Hispanic newborns, but it increased among Hispanic newborns. In the national data, the CH-incidence rate increased similarly among boys and girls, whereas in Texas (1992-2006), the rate among boys increased significantly more than among girls and varied according to race and ethnicity. In Massachusetts (1995-2007), low birth weight newborns or newborns who had a delayed rise in thyrotropin concentration accounted for the majority of the recent rate increase. Race, ethnicity, sex, and pregnancy outcomes have affected the observed increasing incidence rate of CH, although there have been some inconsistencies and regional differences. The association with preterm birth or low birth weight could reflect the misclassification of some cases of transient hypothyroxinemia as true CH. Future studies of risk factors should focus on correct initial identification and reporting of demographic characteristics and pregnancy outcomes for cases of CH. In addition, long-term follow-up data of presumed cases of CH should be ascertained to differentiate true cases of CH from cases of transient hypothyroidism.

Future research directions to identify causes of the increasing incidence rate of congenital hypothyroidism in the United States

A workshop to evaluate the reported increasing trend in the incidence rate of primary congenital hypothyroidism (CH) identified by newborn screening was held February 27 and 28, 2008, in Atlanta, Georgia, and was sponsored by the Centers for Disease Control and Prevention, the Health Resources and Services Administration, and the National Newborn Screening and Genetics Resource Center. Through a series of presentations and discussions, this group of experts considered a variety of factors that could be contributing to the perceived increasing trend of the CH-incidence rate, the gaps in knowledge that need to be overcome to identify the causes of the observed trend, and possible future research activities that might resolve the uncertainties surrounding the increasing incidence rate of CH in the United States. On the basis of these discussions, workshop participants concluded that the initial focus of future efforts should be to determine if the increasing CH-incidence rate persists once there is standardization of the diagnostic criteria for the classification of CH versus transient hypothyroidism. In discussions, workshop participants suggested that if the increasing incidence rate of CH could not be explained by definitional issues, then future research could focus on the identification and evaluation of risk factors for CH that might be changing among the US population and, thus, contributing to the observed increasing incidence rate of CH.

Discontinuation of thyroid hormone treatment among children in the United States with congenital hypothyroidism: findings from health insurance claims data

BACKGROUND

Thyroid hormone treatment in children with congenital hypothyroidism can prevent intellectual disability. Guidelines recommend that children diagnosed with congenital hypothyroidism through newborn screening remain on treatment to at least 3 years of age, after which a trial off therapy can determine which children have transient hypothyroidism. The purpose of this study was to describe the rate at which children with congenital hypothyroidism in the United States discontinue thyroid hormone treatment in early childhood.

METHODS

Retrospective analysis of the 2002-2006 MarketScan(R) Commercial Claims and Encounters research databases and the 2001-2005 MarketScan Multi-State Medicaid databases. Children were classified as having congenital hypothyroidism based on billing codes and having filled a prescription for thyroid hormone treatment. Kaplan-Meier curve analysis was used to determine discontinuation rates.

RESULTS

There were a total of 412 Medicaid-enrolled children and 292 privately-insured children with presumed congenital hypothyroidism included in this study. The overall birth prevalence of congenital hypothyroidism across both datasets was about 1 per 2,300. By 36 months, the percentage who had discontinued thyroid replacement treatment was 38% (95% Confidence Interval: 32%-44%). Medicaid-enrolled children had a more rapid decline in the first 24 months of treatment compared to those with private insurance (P = 0.02).

CONCLUSIONS

More than one-third of children treated for congenital hypothyroidism discontinued treatment within 36 months, which is inconsistent with current guidelines. It is not known how many of these children required continued treatment or experience adverse effects from discontinuation. These findings emphasize the critical need for follow-up systems to monitor the outcome of newborn screening.

Update: newborn screening for endocrinopathies

Congenital hypothyroidism and congenital adrenal hyperplasia are included in many newborn screening (NBS) panels worldwide and in all state-sponsored programs in the United States. Both conditions meet the fundamental prerequisites for NBS: high incidence in the population; biomarkers in the dried blood specimen that are easily detected; and, effective therapies to lessen, if not prevent, the sequelae of late or no treatment. In this review, the history of NBS is discussed for these 2 conditions. The technologies and protocols used in their detection, and related subjects such as genetics, and treatment and outcomes, are also discussed.

Programa de Triagem Neonatal do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brasil

O Programa de Triagem Neonatal do Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Brasil, instituído em 1994 diagnosticou, até 2005, 76 crianças com hipotireoidismo congênito, 10 com fenilcetonúria e 25 com hemoglobinopatias, o que representou uma incidência de 1:2.595, 1:19.409, 1:4.120, respectivamente. Foram diagnosticadas 2.747 crianças com traço falciforme (1:37,5 nascidos vivos). A cobertura média do programa foi de 94,5%. Houve uma considerável melhora nos parâmetros de avaliação da qualidade do programa no período, porém, sem atingir os índices ideais. Campanhas visando à maior divulgação da importância da triagem neonatal são necessárias para aumentar a cobertura e a instituição do 3º dia de vida do recém-nascido como sendo o Dia do Teste do Pezinho poderia contribuir para que idades mais precoces de tratamento fossem atingidas, melhorando o prognóstico das crianças acometidas.

Improvement in screening performance and diagnosis of congenital hypothyroidism in Scotland 1979-2003

AIM

To assess the Scottish newborn screening programme for congenital hypothyroidism from 1994 to 2003 (period 2) for performance and compare with an initial audit covering 1979 to 1993 (period 1).

DESIGN

Performance data-age at blood spot sampling, notification by screening laboratory, start of treatment, and the prevalence of late testing, notification or treatment-were compared, together with the incidence of congenital hypothyroidism.

RESULTS

Comparing data for period 2 with period 1, the mean annual incidence of true congenital hypothyroidism was 1:3655 live births v 1:4363. Median age for Guthrie sampling (all referrals) was 6 v 7 days (p<0.0001). Late sampling (>10 days) had fallen from 10.7% to 7%. For infants requiring repeat sampling before notification, the median (range) interval between initial and final repeat samples was 11 (1 to 52) compared with 14 (3 to 73) days. Median age at notification for true congenital hypothyroidism was 10 v 12 days (p <0.0001). Late notification (>15 days) was justifiable (mild TSH elevation) in 10 of 13 patients in period 2. Median age at start of treatment for true congenital hypothyroidism had improved to 11 days from 13.5 days. For true congenital hypothyroidism, late treatment (>16 days) occurred in 7% of patients compared with 19% (p<0.0001).

CONCLUSIONS

There has been an improvement in performance measures for the congenital hypothyroidism screening programme in Scotland. However, late sampling, occurring primarily in inpatients and which is never justified, remains a problem, while the interval between initial and recall sampling is a further source of delay.

Congenital hypothyroidism and the second newborn metabolic screening in Colorado, USA

OBJECTIVE

To evaluate the effectiveness of a second newborn screening for congenital hypothyroidism (CH).

METHODS

All infants born in Colorado, USA, from July 1996 through June 2004 had a total thyroxine measured with secondary thyroid stimulating hormone determination.

RESULTS

The number of first and second newborn screens completed was 494,324 and 471,877, respectively. The first screen identified 185 cases of CH (incidence of 1:2,703). The second screen identified an additional 42 cases. Overall, the incidence based on both the first and second screenings was 1:2,174. The false negative rate for the first screen was 15.6%. In the absence of a second screen, one infant with CH out of every 11,111 babies screened would have been missed. The addition of the second screen increased the cost-per-case identified from dollars 6,108 to dollars 9,730.

CONCLUSIONS

With only one newborn screen for CH, the number of missed cases is significant and higher than previously reported.

The epidemiology of mental retardation: challenges and opportunities in the new millennium

There are a number of problems and challenges in relating the science of epidemiology to mental retardation (MR). These relate to how MR is defined and classified and how these definitions may change over time. These as well as other differences in ascertainment sources and methods need to be considered when comparing MR prevalence over time and place. On the other hand, advances in technology also provide new and efficient methods of data collection both by data linkage and by use of web-based methods to study rare diseases. While prevalence studies have not been individually reviewed, we have examined the range of data including recent studies relating to how prevalence differs according to age, gender, social class and ethnicity. Some problems with available etiological classification systems have been identified. Recent etiological studies, most of which use different classification systems, have been reviewed and explanations have been postulated to account for differences in results. Individual risk factors for MR are considered whilst the option of considering a population as opposed to a high risk strategy to MR prevention is raised. This might well involve improving the social milieu surrounding the occurrence of individual risk factors. The impact of biotechnological advances such as antenatal and neonatal screening and assisted reproduction on MR are discussed. The issue of how inequalities in access to technology may impact on case identification and even have the potential to further widen inequalities is raised. The importance of extending the use of epidemiological tools to study the social, health and economic burden of MR is also emphasized. However, in order to apply to MR the "prevention-intervention-research" cycle, which surely underpins all epidemiology, it is vital to ensure that the methodological challenges we raise are adequately addressed.