Optimising outcome in congenital hypothyroidism; current opinions on best practice in initial assessment and subsequent management

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.

[Newborn screening for congenital hypothyroidism and congenital adrenal hyperplasia: Benefits and costs of a successful public health program]

Newborn screening is an important public health program and a triumph of preventive medicine. Economic analyses show that the benefits of newborn screening clearly outweigh the costs for certain diseases, but not necessarily for other ones. This is due to the great diversity of the natural history of the diseases detected, to the fact that each of these diseases considered individually is rare, and to differences in the effectiveness of interventions. In addition, the benefit-cost ratio of screening for a particular disorder may differ between countries, specifically between high-income and low- and middle-income countries. The burden of a disorder may also be alleviated by increased clinical awareness and effective clinical services, even in the absence of newborn screening. In this article, we focus on economic analyses of newborn screening for primary congenital hypothyroidism, which has been in place in high-income countries for roughly 40 years, and for classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Screening for the latter is not yet universal, even in high-income countries, although the lack of universal implementation may reflect factors other than economic considerations.

Association of elevated neonatal thyroid-stimulating hormone levels with school performance and stimulant prescription for attention deficit hyperactivity disorder in childhood

Untreated severe newborn thyroid deficiency causes neurocognitive impairment; however, the impact of mild thyroid deficiency is not known. This study aimed to examine whether mildly elevated neonatal thyroid-stimulating hormone (TSH) levels are associated with poor school performance or stimulant prescription for attention deficit hyperactivity disorder (ADHD). This record-linkage study included 232,790 term-born infants in Australia with a TSH level below newborn screening threshold (< 15 mIU/L). Among our cohort, as TSH levels increased, the proportion of infants born low birthweight via caesarean section and with disadvantaged socioeconomic status increased. Multivariable logistic regression analysis showed that, compared with infants with 'normal' neonatal TSH level (< 5 mIU/L), those with neonatal TSH 10-15 mIU/L had an increased risk of being exempt from school testing (aOR 1.63 (95% CI 1.06-2.69)) or prescribed a stimulant for ADHD (aOR 1.57 (95% CI 1.10-2.24)), adjusted for perinatal and sociodemographic factors. Among a nested analysis of 460 sibling pairs, siblings with 'mildly elevated' TSH levels were more likely to be exempt from school tests compared with siblings with normal TSH levels (aOR 2.53, 95% CI 1.01-6.33).Conclusion: In this population cohort and sibling analysis, mildly elevated neonatal TSH levels were associated with being exempt from school testing due to significant or complex disability. What is Known: • Newborn screening for severe thyroid hormone deficiency has virtually eliminated congenital hypothyroidism-associated intellectual disability in developed countries. • The impact of mild thyroid hormone deficiency in infants is unclear. What is New: • Children with a mildly elevated neonatal TSH level below current newborn screening cut-offs have an increased likelihood of being exempt from school testing due to significant or complex disability compared with siblings and peers. This study includes a population-based and nested sibling analysis.

White matter microstructural abnormalities in children with severe congenital hypothyroidism

This study assessed white matter microstructural integrity and behavioral correlates for children with severe congenital hypothyroidism (CH) who were identified and treated early following newborn screening. Eighteen children with severe CH and 21 healthy controls underwent a battery of behavioral measures of hearing, language and communication, along with diffusion MR imaging. Tract-based spatial statistics were performed on standard diffusion parameters of fractional anisotropy and diffusivity metrics. Microscopic diffusion anisotropy mapping based on the Spherical Mean Technique was also used to evaluate biologically specific metrics. Compared with age-matched controls, children with severe CH had poorer hearing and communication skills, albeit generally within normal limits. Children with severe CH had fractional anisotropy that was significantly lower in the cerebellum, bilateral thalami and right temporal lobe, and radial diffusivity that was significantly higher in the cerebellum and bilateral thalami. Microscopic fractional anisotropy and intra-neurite volume fraction were also significantly decreased, and transverse microscopic diffusivity was significantly increased, in the CH group in areas including the cerebellum, thalamus, occipital lobe, and corpus callosum, and in the white matter adjacent to sensorimotor cortex, particularly in the left hemisphere. Significant and widespread correlations were observed between behavioral measures and measures of white matter microstructural integrity in children with CH. The results indicate that children with severe CH who are identified through newborn screening may have significant brain white matter microstructural abnormalities despite early treatment.

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Children with severe CH show reductions in white matter microstructural integrity.

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Hearing and communication abilities are impaired for some children with severe CH.

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White matter abnormalities are associated with communication abilities in CH.

Trends in Scottish newborn screening programme for congenital hypothyroidism 1980-2014: strategies for reducing age at notification after initial and repeat sampling

OBJECTIVES

To determine ages at first capillary sampling and notification and age at notification after second sampling in Scottish newborns referred with elevated thyroid-stimulating hormone (TSH).

SUBJECTS AND METHODS

Referrals between 1980 and 2014 inclusive were grouped into seven 5-year blocks and analysed according to agreed standards.

RESULTS

Of 2 116 132 newborn infants screened, 919 were referred with capillary TSH elevation ≥8 mU/L of whom 624 had definite (606) or probable (18) congenital hypothyroidism. Median age at first sampling fell from 7 to 5 days between 1980 and 2014 (standard 4-7 days), with 22, 8 and 3 infants sampled >7 days during 2000-2004, 2005-2009 and 2010-2014. Median age at notification was consistently ≤14 days, range falling during 2000-2004, 2005-2009 and 2010-2014 from 6 to 78, 7-52 and 7-32 days with 12 (14.6%), 6 (5.6%) and 5 (4.3%) infants notified >14 days. However 18/123 (14.6%) of infants undergoing second sampling from 2000 onwards breached the ≤26-day standard for notification. By 2010-2014, the 91 infants with confirmed congenital hypothyroidism had shown favourable median age at first sample (5 days) with start of treatment (10.5 days) approaching age at notification.

CONCLUSION

Most standards for newborn thyroid screening are being met by the Scottish programme, but there is a need to reduce age range at notification, particularly following second sampling. Strategies to improve screening performance include carrying out initial capillary sampling as close to 96 hours as possible; introducing 6-day laboratory reporting and use of electronic transmission for communicating repeat requests.

Neonatal Screening for Congenital Hypothyroidism with Focus on Developing an Indian Screening Programme

Neonatal screening for congenital hypothyroidism, along with eradication of iodine deficiency in large parts of the world, has made it possible to prevent the development of permanent neurological impairment due to thyroid hormone deficiency in the developing brain. The first successful screening programme was demonstrated in Canada in 1973 and since then it has been standard of care in most developed societies. In India there is no national programme for neonatal screening, and screening is only done in selected larger hospitals on newborns whose parents fund it. This review summarises the current understanding of the various strategies for newborn screening that could potentially be employed in India with resource constraints. Once a case is detected, the further evaluation and determination of etiology is summarised. Treatment and long term follow-up with levothyroxine replacement is also described in detail as per current understanding.

Congenital hypothyroidism and thyroid dyshormonogenesis: a case report of siblings with a newly identified mutation in thyroperoxidase

BACKGROUND

Thyroid dyshormonogenesis continues to be a significant cause of congenital hypothyroidism. Over time, forms of thyroid dyshormonogenesis can result in goiter, which can lead to difficult management decisions as the pathologic changes can both mimic or lead to thyroid cancer.

METHODS

Herein we describe the cases of two brothers diagnosed with congenital hypothyroidism, with initial findings consistent with thyroid dyshormonogenesis. One brother eventually developed multinodular goiter with complex pathology on biopsy, resulting in thyroidectomy.

RESULTS

Whole exome sequencing revealed the brothers carry a novel frameshift mutation in thyroperoxidase; the mutation, while not previously described, was likely both deleterious and pathogenic. Conlcusions: These cases highlight the complex pathology that can occur within thyroid dyshormonogenesis, with similar appearance to possible thyroid cancer, leading to complex management decisions. They also highlight the role that a genetic diagnosis can play in interpreting the impact of dyshormonogenesis on nodular thyroid development, and the need for long-term follow-up in these patients.

Final height in Italian patients with congenital hypothyroidism detected by neonatal screening: a 20-year observational study

BACKGROUND

Linear growth and final height are reported as normal in congenital hypothyroid patients in the neonatal screening era.

METHODS

We evaluated the final height in 215 patients with congenital hypothyroidism to assess if it improved over the last 2 decades.

RESULTS

Final height (-0.1 ± 1.0 SDS) was higher than target height (-0.8 ± 1.0 SDS, p < 0.001) and not different among the 4 quartiles for birthdate. It was correlated with target height (r(2) = 0.564, p < 0.001) and height at puberty onset (r(2) = 0.685, p < 0.001), but not with age at diagnosis or the starting LT4/kg/day dose. The curve fitting analysis showed that the age at diagnosis progressively decreased during the 20-year study period, while the target height and the starting LT4/kg/day increased. Final height was not affected by the birthdate, the age at diagnosis, the starting LT4 dose.

CONCLUSIONS

The final height is higher than the target height, but despite the improvement in the screening and the treatment, it did not improve over the last 20 years. These findings are in keeping with the described secular trend and suggest that earlier diagnosis and replacement therapy do not significantly modify final height in these patients.

Ultrasonography of various thyroid diseases in children and adolescents: a pictorial essay

Thyroid imaging is indicated to evaluate congenital hypothyroidism during newborn screening or in cases of a palpable thyroid mass in children and adolescents. This pictorial essay reviews the ultrasonography (US) of thyroid diseases in children and adolescents, including normal thyroid gland development, imaging features of congenital thyroid disorders (dysgenesis, [aplasia, ectopy, hypoplasia], dyshormonogenesis, transient hypothyroidism, thyroglossal duct cyst), diffuse thyroid disease (Grave's disease, Hashimoto's thyroiditis, and suppurative thyroiditis), and thyroid nodules. The primary imaging modalities for evaluating thyroid diseases are US and radionuclide scintigraphy. Additionally, US can be used to guide aspiration of detected nodules.

Unusual course of congenital hypothyroidism and route of the L-thyroxine treatment in a preterm newborn

Congenital hypothyroidism (CH) is the most common endocrine pathology in neonates. Inappropriate treatment of CH is complicated by irreversible brain damage or low IQ score. Hormone replacement therapy with L-thyroxine (L-T4) is sufficient for a very large proportion of patients. However, during treatment, the patient needs to be carefully monitored for presence of factors which might affect the absorption or bio-availability of the drug as well as its dose. Herein, we report a preterm newborn with CH who presented with gastrointestinal problems mimicking necrotizing enterocolitis. The clinical course was also complicated by cholestasis. The L-T4 replacement treatment was switched from oral route to parenteral. After resolution of the cholestasis, L-T4 treatment was continued successfully by the oral route.

What has national screening program changed in cases with congenital hypothyroidism?

OBJECTIVE

Since congenital hypothyroidism (CH) is the most important cause of preventable mental retardation, its screening is important. In this present study, it was aimed to evaluate congenital hypothyroidism cases before and after the initiation of screening program in year 2007 in our country.

METHODS

A total of 400 patients diagnosed with CH at our outpatient clinic were retrospectively evaluated. Age of diagnosis, complaint, clinical signs, and etiological distribution were detected and changes in those parameters were evaluated before and after year 2007, which was the initiation date of our national screening program. Findings : After year 2007, 70.6% of patients were diagnosed in the first month; 21.2% in 1-3 months; 6.5% in 3-6 months, and no patient was diagnosed after 9 months. Before initiation of the screening program, 48.4% of cases were diagnosed in the first month, the percentage was increased to 62.8% after the program; the increase was significant. While mental retardation was detected in 13.3% of patients before the screening, it was decreased to 4% after initiation of the program. An interesting finding was that age of treatment onset in girls was significantly higher than in boys before the screening; there was no difference between them after initiation of the screening.

CONCLUSION

In this present study, it was observed that ages of diagnosis and treatment as well as mental retardation rates were significantly decreased in girls after the screening program, but ideal results have not been reached yet, and is expected to be reached in the future.

Establishment and development of a national newborn screening programme for congenital hypothyroidism in Turkey

OBJECTIVE

To assess the Turkish National Newborn Screening Programme (NNSP) for congenital hypothyroidism (CH). Retrospective study based on the data from NNSP.

METHODS

Since December 2006, a nationwide screening programme for CH has been conducted in Turkey by the Turkish Directorate of Public Health (TDPH) in cooperation with several institutions. We evaluated the database between January 2008 and July 2010 of this programme. According to the methodology of the NNSP, between three and five days of age (or at discharge from the hospital, if this occurs earlier) blood specimens were routinely collected from neonates on filter paper, by puncturing the heel. The accepted thyroid-stimulating hormone cut-off level for recall was 20 mU/L initially and 15 mU/L subsequently. The incidence of possible CH by years was reported.

RESULTS

During the evaluation period, 3223765 newborns were tested. The mean annual incidence of possible CH showed a gradual increase over the years (1:888 in 2008, 1:592 in 2009, and 1:469 in 2010). Regional differences were noted. Although the mean age of blood sampling did not change by years, the mean age at notification for suspected CH decreased from 19.2 to 15.7 days from 2008 to 2010.

CONCLUSIONS

We reported the first assessment of NNSP in Turkey. An improvement in performance measures for the CH screening programme has been noted. Knowledge on incidence of confirmed CH is not yet available in the database.