Increase in doses of levothyroxine at the age of 3 years and above is useful for distinguishing transient and permanent congenital hypothyroidism

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.

Permanent vs Transient Congenital Hypothyroidism in Chinese Children: Physical Growth and Predictive Nomogram

CONTEXT

Few reliable markers are available to distinguish transient congenital hypothyroidism (TCH) and permanent congenital hypothyroidism (PCH). Additionally, the differences in growth between TCH and PCH remain unclear.

OBJECTIVE

To investigate the growth of children with TCH and PCH and develop a nomogram for early differentiation of these forms.

METHODS

This retrospective study included children with TCH or PCH. The predictive efficacy of the prognostic predictors was analyzed using receiver operating characteristic analysis. Multivariate prediction models were developed. Measurements of growth were compared between groups.

RESULTS

Patients with TCH had lower initial thyroid-stimulating hormone (TSH) than those with PCH at newborn screening (NBS). The supplementary dose of levothyroxine (L-T4) gradually decreased with age in TCH but not in PCH. The area under the curve (AUC) values of the initial TSH, L-T4 dose at 1 year of age, and L-T4 dose at 2 years of age for distinguishing TCH from PCH were 0.698, 0.71, and 0.879, respectively. The predictive efficacy of the multivariate models at 1 and 2 years of age improved, with AUC values of 0.752 and 0.922, respectively. A nomogram was built based on the multivariate model at 1 year of age. The growth did not differ between children with TCH and those with PCH. However, at 1 year of age, girls with CH exhibited higher z-scores in terms of height and weight than boys with CH.

CONCLUSION

TSH at NBS and L-T4 doses during treatment can be used to distinguish between PCH and TCH early in life, and the predictive efficacy can be improved using multivariable models with a visualized nomogram. At 3 years of age, patients with TCH and PCH showed similar growth.

Knowns and unknowns about congenital hypothyroidism: 2022 update

Several excellent guidelines and expert opinions on congenital hypothyroidism (CH) are currently available. Nonetheless, these guidelines do not address several issues related to CH in detail. In this review, the authors chose the following seven clinical issues that they felt were especially deserving of closer scrutiny in the hope that drawing attention to them through discussion would help pediatric endocrinologists and promote further interest in the treatment of CH. 1. How high should the levothyroxine (L-T4) dose be for initial treatment of severe and permanent CH? 2. What is the optimal method for monitoring treatment of severe CH? 3. At what level does maternal iodine intake during pregnancy affect fetal and neonatal thyroid function? 4. Does serum thyroglobulin differ between patients with a dual oxidase 2 (DUOX2) variants and those with excess iodine? 5. Who qualifies for a genetic diagnosis? 6. What is the best index for distinguishing transient and permanent CH? 7. Is there any cancer risk associated with CH? The authors discussed these topics and jointly edited the manuscript to improve the understanding of CH and related issues.

Guidelines for Newborn Screening of Congenital Hypothyroidism (2021 Revision)

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

Screening of frequent variants associated with congenital hypothyroidism: a comparison with next generation sequencing

Congenital hypothyroidism (CH) is considered the most common congenital endocrine disorder of genetic origin. Next generation sequencing (NGS) is the standard method for identifying genetic mutations, but it is an expensive and complex technique. Therefore, we propose to use Sanger sequencing to identify selected variants of the four most common CH-causative genes: DUOX2, TG, TSHR, and PAX8. To analyze the performance of Sanger sequencing, we compared its variant detection ability with that of a CH NGS panel containing 53 genes. We performed Sanger sequencing of selected variants and panel NGS analysis of 25 Japanese patients with CH. Sanger sequencing identified nine variants in seven patients, while NGS identified 24 variants in 14 patients. Of these, eight, five, eight, two, and one were found to be potentially pathogenic in DUOX2, TSHR, TG, UBR1, and TPO genes, respectively. The percentage of detectable variants using Sanger sequencing compared with NGS was 37.5% (9/24 variants), whereas the percentage of detectable cases carrying variants using Sanger sequencing compared with NGS was 50% (7/14 patients). We proposed a system for screening commonly identified CH-related variants by Sanger sequencing. Sanger sequencing could therefore identify about a third of CH-causative variants, so is considered an effective and efficient form of pre-screening before NGS.

Diagnostic Re-Evaluation and Potential Predictor Factors of Transient and Permanent Congenital Hypothyroidism in Eutopic Thyroid Gland

Background: The incidence of congenital hypothyroidism (CH) has increased over the years, and many predictors for detecting newborns with transient forms (TCH) as early as possible have been considered. Methods: All newborns diagnosed with primary CH and eutopic gland in the Piedmont region of Italy in the period of January 2014–June 2019 were enrolled and re-evaluated at the age of 2 years. Results: 105 newborns were diagnosed with CH during the study period. Dyshormonogenesis was observed in 55/105. At re-evaluation, we found that 52.7% had permanent CH (PCH), while 47.3% had TCH. Male/female rate, TSH levels at diagnosis, levothyroxine requirement at withdrawal and extra-thyroid congenital malformations rate were higher in the PCH group (p = 0.02, p = 0.009, p = 0.02 and p = 0.01), while fT4 levels at diagnosis were lower (p = 0.03). Sensitivity of 72.4% and specificity of 80.7% for serum TSH above 60 mcUI/mL, sensitivity of 73% and specificity of 72.4% for serum fT4 level below 7.2 pg/mL and sensitivity of 66% and specificity of 68% for drug requirement above 2.25 mcg/kg/day were observed in PCH. Conclusions: Demographic, clinical and hormonal data at diagnosis and levothyroxine requirement during the first two years should be adequately monitored to identify infants who are most likely to discontinue therapy after the age of 24 months.

Newborn Screening for Congenital Hypothyroidism in Japan

Congenital hypothyroidism (CH) is the most common preventable cause of intellectual impairment or failure to thrive by early identification and treatment. In Japan, newborn screening programs for CH were introduced in 1979, and the clinical guidelines for newborn screening of CH were developed in 1998, revised in 2014, and are currently undergoing further revision. Newborn screening strategies are designed to detect the elevated levels of thyroid stimulating hormone (TSH) in most areas of Japan, although TSH and free thyroxine (FT4) are often measured simultaneously in some areas. Since 1987, in order not to observe the delayed rise in TSH, additional rescreening of premature neonates and low birth weight infants (<2000 g) at four weeks of life or when their body weight reaches 2500 g has been recommended, despite a normal initial newborn screening. Recently, the actual incidence of CH has doubled to approximately 1:2500 in Japan as in other countries. This increasing incidence is speculated to be mainly due to an increase in the number of mildly affected patients detected by the generalized lowering of TSH screening cutoffs and an increase in the number of preterm or low birth weight neonates at a higher risk of having CH than term infants.