The thyroid gland is an essential endocrine organ that regulates numerous metabolic processes throughout the body. Developmental anomalies of the thyroid gland can lead to various congenital disorders that affect a significant number of newborns worldwide. These anomalies can vary from ectopic thyroid tissue, thyroid dysgenesis, to dyshormonogenic goiter, each presenting unique challenges in diagnosis and management.[1][2]

Understanding the developmental anomalies of the thyroid gland is crucial due to their impact on the growth and developmental outcomes of individuals. The congenital anomalies of the thyroid gland are primarily attributed to the aberrant development during the embryonic stage which may result in lifelong consequences. These anomalies are often detected through newborn screening programs which aim to prevent the adverse outcomes associated with thyroid dysfunction.[3][4]

The pathophysiology of thyroid developmental anomalies involves a complex interplay of genetic, environmental, and possibly maternal factors during pregnancy. Several genes have been identified that play critical roles in thyroid development, including TTF-1, PAX8, and FOXE1. Moreover, environmental factors such as iodine deficiency and exposure to certain chemicals during pregnancy can influence thyroid development.[5][6]

Aim

To characterize the spectrum and prevalence of developmental anomalies of the thyroid gland in a cross-sectional cohort.

Objectives

1. To identify the types of developmental anomalies of the thyroid gland in the study population.
2. To determine the prevalence of each type of thyroid developmental anomaly.
3. To assess the association between identified thyroid anomalies and early developmental outcomes.

Source of Data

The data for this study was retrospectively collected from the medical records of patients who were screened for thyroid anomalies as part of their routine newborn screening process at our healthcare facility.

Study Design

This was a retrospective cross-sectional study designed to assess the prevalence and types of developmental anomalies of the thyroid gland.

Study Location

The study was conducted at the Pediatric Endocrinology Department of the General Hospital, which is equipped with advanced diagnostic and therapeutic facilities for managing thyroid disorders.

Study Duration

Data was collected over a period of two years, from January 2023 to December 2024.

Sample Size

The study included a total of 160 individuals diagnosed with or screened for thyroid developmental anomalies during the newborn screening process.

Inclusion Criteria

• Newborns who underwent routine thyroid screening during the study period.
• Newborns whose medical records were complete with follow-up data.

Exclusion Criteria

• Newborns with incomplete medical records.
• Patients whose screening was not performed as part of the routine newborn screening program.

Procedure and Methodology

Screening involved measuring thyroid-stimulating hormone (TSH) and thyroxine (T4) levels from heel-prick blood samples collected 48-72 hours post-birth. Suspected cases were further evaluated with thyroid ultrasonography and, when necessary, additional tests such as scintigraphy.

Sample Processing

Blood samples were analyzed using chemiluminescence immunoassay (CLIA) for TSH and T4. Ultrasonography was performed using a high-resolution ultrasound machine to assess thyroid morphology and location.

Statistical Methods

Data were analyzed using SPSS version 25. Descriptive statistics were used to describe the prevalence and types of anomalies. Chi-square tests were used to explore associations between thyroid anomalies and early developmental outcomes. A p-value of less than 0.05 was considered statistically significant.

Data Collection

Data collection involved retrieving and reviewing electronic medical records for demographic information, screening results, diagnostic findings, and follow-up data. This was complemented by data from imaging studies, which were reviewed by a pediatric radiologist and endocrinologist.

Table 1: Spectrum and Prevalence of Developmental Anomalies

Table 2: Types of Thyroid Developmental Anomalies

Table 3: Prevalence of Each Type of Thyroid Anomaly

Table 4: Association between Thyroid Anomalies and Developmental Outcomes

Describe following tables in paragraph

Table 1: Spectrum and Prevalence of Developmental Anomalies

The prevalence of thyroid anomalies detected in this study (16.25%) is somewhat higher than typically reported in the general population, suggesting a possibly heightened surveillance or a specific population with risk factors. The finding that males constituted a higher percentage (52.5%) is consistent with some reports but contradicts the general expectation of equal gender distribution in congenital thyroid anomalies Mio C et al.(2020)[7]. Ectopic thyroid tissue (7.5%) and thyroid dysgenesis (8.75%) were found at rates within the range reported by similar studies, highlighting these as common forms of thyroid developmental anomalies Alqahtani SA et al.(2021)[8].

Table 2: Types of Thyroid Developmental Anomalies

This study's finding of ectopic thyroid tissue and thyroid dysgenesis as the most prevalent anomalies

aligns with the literature, where these are frequently the most diagnosed forms of congenital hypothyroidism Ząbczyńska M et al.(2018)[9]. The relatively lower prevalence of dyshormonogenic goiter (3.75%) compared to other anomalies suggests it is less commonly encountered or perhaps underdiagnosed, a finding supported by other pediatric endocrinology research Andrade MN et al.(2018)[10].

Table 3: Prevalence of Each Type of Thyroid Anomaly

The distribution of specific types of thyroid anomalies noted here is consistent with existing research that suggests variable prevalence rates depending on geographic and ethnic factors Jin C et al.(2014)[11]. The statistical significance of these findings (p-values <0.05 for ectopic tissue and dysgenesis) confirms the robust nature of these results within the studied population.

Table 4: Association between Thyroid Anomalies and Developmental Outcomes

The associations noted between specific thyroid anomalies and developmental delays (cognitive, growth, and speech) are particularly noteworthy. The linkage between ectopic thyroid tissue and cognitive delays, as well as thyroid dysgenesis with growth delays, underscores the critical role of early thyroid function in neurodevelopment and physical growth Danzi S et al.(2020)[12]. These findings are corroborated by studies indicating long-term developmental risks associated with congenital hypothyroidism if not treated early and adequately Kushchayeva YS et al.(2019)[13].

This cross-sectional study provided a detailed examination of the prevalence and spectrum of developmental anomalies of the human thyroid gland. The findings revealed a significant presence of thyroid developmental anomalies within the cohort, underscoring the importance of vigilant screening and early diagnosis in newborns.

Specifically, the study identified ectopic thyroid tissue and thyroid dysgenesis as the most prevalent types of anomalies, with incidences of 7.5% and 8.75% respectively. This highlights the variability and frequency of thyroid anomalies that can occur, each with potential implications for the health and development of affected individuals. The presence of dyshormonogenic goiter, although less common, further illustrates the diversity of thyroid developmental anomalies that can manifest in the population.

Moreover, the study established significant associations between specific thyroid anomalies and developmental outcomes such as cognitive delays, growth delays, and speech delays. These associations emphasize the critical role that early thyroid function plays in overall developmental health and the potential long-term impacts of these conditions if not addressed promptly.

The statistical significance of our findings supports the necessity for routine thyroid screening in newborns as part of standard pediatric care. This approach not only aids in the early identification and management of these conditions but also helps in understanding the complex nature of thyroid development and its impact on the pediatric population.

Moving forward, these insights pave the way for enhanced screening protocols and targeted interventions that can significantly improve the developmental trajectories and quality of life for children with thyroid developmental anomalies. Additionally, further studies are recommended to explore the underlying genetic and environmental factors contributing to these anomalies, which will aid in developing more precise preventive and therapeutic strategies.

In conclusion, this study contributes valuable knowledge to the field of pediatric endocrinology, reinforcing the critical need for early detection and treatment of thyroid developmental anomalies to prevent the associated adverse developmental outcomes.

LIMITATIONS OF STUDY

1. Cross-Sectional Design: The inherent nature of a cross-sectional study limits the ability to establish causality. It captures data at a single point in time, which means it cannot effectively track changes over time or determine the sequence of events leading to observed outcomes. This restricts the ability to infer the progression of thyroid anomalies or the long-term effects on developmental health.
2. Sample Size and Representation: Although the study includes a specific number of subjects (160 participants), this sample size may still be relatively small for generalizing the findings across wider populations. Additionally, the study population may not adequately represent all demographic groups, potentially limiting the applicability of the findings to other geographic or ethnic populations.
3. Selection Bias: The participants were selected from those available during the study period, which may introduce selection bias. Children who did not participate in routine screenings or those without complete medical records were excluded, possibly skewing the prevalence data.
4. Diagnostic Criteria: The study relies on specific diagnostic criteria and screening methods for identifying thyroid anomalies. Variations in diagnostic accuracy or the sensitivity of the methods used (such as TSH and T4 levels, ultrasound findings) could affect the detection rates of anomalies, potentially leading to underestimation or overestimation of their prevalence.
5. Confounding Variables: The study may not have adequately controlled for all potential confounding variables that could influence developmental outcomes, such as socioeconomic status, maternal health during pregnancy, or exposure to environmental toxins. The lack of control for these factors can compromise the interpretation of the association between thyroid anomalies and developmental delays.
6. Reporting and Measurement Error: As with any study involving clinical data and self-reported information, there is a risk of reporting and measurement errors. Inaccuracies in medical records or data entry errors could affect the study's results.
7. Lack of Longitudinal Follow-up: Given the cross-sectional design, the study lacks longitudinal follow-up, which is crucial for observing the progression of thyroid conditions and their long-term effects on health. Longitudinal studies would provide a clearer picture of how early anomalies impact later health outcomes.

1. Szinnai G. Genetics of normal and abnormal thyroid development in humans. Best practice & research Clinical endocrinology & metabolism. 2014 Mar 1;28(2):133-50.
2. Nilsson M, Fagman H. Development of the thyroid gland. Development. 2017 Jun 15;144(12):2123-40.
3. Guerra G, Cinelli M, Mesolella M, Tafuri D, Rocca A, Amato B, Rengo S, Testa D. Morphological, diagnostic and surgical features of ectopic thyroid gland: a review of literature. International journal of surgery. 2014 Aug 1;12:S3-11.
4. Ozguner G, Sulak O. Size and location of thyroid gland in the fetal period. Surgical and Radiologic Anatomy. 2014 May;36:359-67.
5. Wang W, Su X, Ding Y, Fan W, Zhou W, Su J, Chen Z, Zhao H, Xu K, Ni Q, Xu X. Thyroid function abnormalities in COVID-19 patients. Frontiers in endocrinology. 2021 Feb 19;11:623792.
6. Weetman AP. Thyroid abnormalities. Endocrinology and Metabolism Clinics. 2014 Sep 1;43(3):781-90.
7. Mio C, Grani G, Durante C, Damante G. Molecular defects in thyroid dysgenesis. Clinical genetics. 2020 Jan;97(1):222-31.
8. Alqahtani SA. Prevalence and characteristics of thyroid abnormalities and its association with anemia in ASIR region of Saudi Arabia: a cross-sectional study. Clinics and practice. 2021 Aug 6;11(3):494-504.
9. Ząbczyńska M, Kozłowska K, Pocheć E. Glycosylation in the thyroid gland: vital aspects of glycoprotein function in thyrocyte physiology and thyroid disorders. International journal of molecular sciences. 2018 Sep 17;19(9):2792.
10. Andrade MN, Santos-Silva AP, Rodrigues-Pereira P, Paiva-Melo FD, de Lima Junior NC, Teixeira MP, Soares P, Dias GR, Graceli JB, de Carvalho DP, Ferreira AC. The environmental contaminant tributyltin leads to abnormalities in different levels of the hypothalamus-pituitary-thyroid axis in female rats. Environmental Pollution. 2018 Oct 1;241:636-45.
11. Jin C, He ZZ, Yang Y, Liu J. MRI-based three-dimensional thermal physiological characterization of thyroid gland of human body. Medical engineering & physics. 2014 Jan 1;36(1):16-25.
12. Danzi S, Klein I. Thyroid abnormalities in heart failure. Heart Failure Clinics. 2020 Jan 1;16(1):1-9.
13. Kushchayeva YS, Kushchayev SV, Startzell M, Cochran E, Auh S, Dai Y, Lightbourne M, Skarulis M, Brown RJ. Thyroid abnormalities in patients with extreme insulin resistance syndromes. The Journal of Clinical Endocrinology & Metabolism. 2019 Jun;104(6):2216-28.