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PubMed This is a summary of 55 peer-reviewed journal articles Updated
Pediatric Endocrinology

Understanding Athyreosis in Your Newborn

At a Glance

Athyreosis, or thyroid agenesis, is a permanent condition where a baby is born without a thyroid gland. It requires lifelong thyroid hormone replacement. With early and consistent daily medication, children with this condition can grow, develop, and thrive just like their peers.

Receiving a diagnosis of athyreosis for your newborn can feel overwhelming, but it is a manageable condition. While the name sounds complex, it describes a specific physical finding: your baby was born without a thyroid gland. Because the thyroid is responsible for hormones that drive growth and brain development, this diagnosis requires immediate action. However, the most important thing to know is that with early and consistent treatment, children with athyreosis typically grow, learn, and thrive just like their peers [1][2][3].

What is Athyreosis?

Athyreosis (also called thyroid agenesis) is a form of congenital hypothyroidism, a term for any condition where a baby is born with low thyroid hormone levels [4][5]. In most cases of congenital hypothyroidism, the thyroid gland is either too small or is located in the wrong place (such as under the tongue). In athyreosis, the gland did not develop at all during pregnancy [6][7].

This condition is rare, occurring in roughly 1 out of every 1,000 to 4,000 births, depending on the region [8][9]. It is generally a sporadic event, meaning it usually happens by chance rather than being passed down through families [4][10]. Unlike some other forms of thyroid issues that might be temporary, athyreosis is a permanent condition because the physical gland is missing [11][12].

Navigating This Guide

This resource is designed to help you understand your child’s diagnosis and advocate for their care. We recommend reading through the following sections:

01

Causes and Associated Risks: Why It Happens

Learn why athyreosis happens and the genetic causes behind a missing thyroid gland. Understand associated risks and extra screenings your baby may need.

02

Confirming the Diagnosis: Scans and Blood Tests

Learn how doctors confirm an athyreosis diagnosis in newborns. Understand the role of thyroid scintigraphy, ultrasound, TSH, and thyroglobulin blood tests.

03

Management and Monitoring: The Road Ahead

Learn how to manage your infant's athyreosis with daily levothyroxine. Understand dosage guidelines, safe administration tips, and blood test monitoring schedules.

04

Development and What to Expect Long-Term

Learn about the long-term outlook for children with athyreosis. Discover how early levothyroxine treatment supports normal growth, IQ, and development.

05

Part II: For Adults Living with Athyreosis

Learn how to manage athyreosis as an adult. Understand lifelong levothyroxine treatment, transitioning your care, and planning for a healthy pregnancy.

Your pediatric endocrinologist will become a key partner in your child’s health. By educating yourself, you are taking the first crucial step in ensuring your baby has everything they need to succeed [13][14].

Common questions in this guide

What is athyreosis?
Athyreosis, also known as thyroid agenesis, is a permanent condition where a baby is born completely without a thyroid gland. It is a specific type of congenital hypothyroidism that prevents the body from producing essential hormones for growth and brain development.
Is athyreosis a genetic condition passed down from parents?
In most cases, athyreosis is a sporadic event, meaning it happens by chance during pregnancy. It is rarely passed down through families or inherited.
How is an athyreosis diagnosis confirmed in a newborn?
Doctors typically confirm the diagnosis using an ultrasound and a nuclear scintigraphy scan to visually verify that the thyroid gland is missing. They will also use blood tests to measure your baby's exact TSH and T4 hormone levels.
Can a baby with athyreosis live a normal life?
Yes. Although it is a permanent condition, early and consistent daily medication replaces the missing hormones. With proper treatment and regular monitoring, children born without a thyroid gland typically grow, learn, and develop normally.
Will my baby need other health screenings if they have athyreosis?
Because athyreosis can sometimes be linked to other congenital conditions, your pediatric endocrinologist may recommend additional routine screenings to check your baby's heart and hearing.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Was my baby's diagnosis confirmed with both an ultrasound and a nuclear scintigraphy scan?
  2. 2.What were my baby's exact TSH and T4 levels at the time of diagnosis?
  3. 3.What is the target range for these levels during the first year of life?
  4. 4.Since athyreosis is sometimes linked to other conditions, should we screen for heart or hearing issues?
  5. 5.How often will we need to do blood tests to adjust the medication dose as my baby grows?

Questions For You

Tap a prompt to share your answer — we'll use it plus this page's context to start a tailored conversation.

References

References (14)
  1. 1

    Evaluation and management of the child with hypothyroidism.

    Leung AKC, Leung AAC

    World journal of pediatrics : WJP 2019; (15(2)):124-134 doi:10.1007/s12519-019-00230-w.

    PMID: 30734891
  2. 2

    [Cognitive performance of preschoolers with Congenital Hypothyroidism enrolled in a follow-up program].

    Ontiveros M E, González M JA, Rivera G R, et al.

    Andes pediatrica : revista Chilena de pediatria 2023; (94(1)):62-69 doi:10.32641/andespediatr.v94i1.4356.

    PMID: 37906872
  3. 3

    Clinical Insight into Congenital Hypothyroidism Among Children.

    Korkmaz HA

    Children (Basel, Switzerland) 2025; (12(1)) doi:10.3390/children12010055.

    PMID: 39857886
  4. 4

    Sublingual thyroid ectopy: similarities and differences with Kallmann syndrome.

    Van Vliet G, Deladoëy J

    F1000prime reports 2015; (7()):20 doi:10.12703/P7-20.

    PMID: 25750738
  5. 5

    Genetics of primary congenital hypothyroidism-a review.

    Kostopoulou E, Miliordos K, Spiliotis B

    Hormones (Athens, Greece) 2021; (20(2)):225-236 doi:10.1007/s42000-020-00267-x.

    PMID: 33400193
  6. 6

    Congenital Hypothyroidism: Long-Term Experience with Early and High Levothyroxine Dosage.

    Uyttendaele M, Lambert S, Tenoutasse S, et al.

    Hormone research in paediatrics 2016; (85(3)):188-97 doi:10.1159/000443958.

    PMID: 26881423
  7. 7

    Resistance to thyroid hormone in a child with thyroid agenesis: A case report with review of the literature.

    Hasan KM, Mohammed BA, Ahmed SF, et al.

    Annals of medicine and surgery (2012) 2022; (77()):103569 doi:10.1016/j.amsu.2022.103569.

    PMID: 35638026
  8. 8

    Newborn screening for congenital hypothyroidism in Henan province, China.

    Zhao DH, Shen Y, Gong JM, et al.

    Clinica chimica acta; international journal of clinical chemistry 2016; (452()):58-60.

    PMID: 26522654
  9. 9

    Incidence rate and geographic distribution of congenital hypothyroidism in the southwest of Iran (Kohgiluyeh and Boyer Ahmad province) based on geographic information system since 2011-2020.

    Ghatee MA, Manzouri L, Kheiri M, Parad M

    BMC pediatrics 2024; (24(1)):790 doi:10.1186/s12887-024-05292-y.

    PMID: 39614209
  10. 10

    Whole-Exome Sequencing in Congenital Hypothyroidism Due to Thyroid Dysgenesis.

    Larrivée-Vanier S, Jean-Louis M, Magne F, et al.

    Thyroid : official journal of the American Thyroid Association 2022; (32(5)):486-495 doi:10.1089/thy.2021.0597.

    PMID: 35272499
  11. 11

    Fetal and Neonatal Thyroid Dysfunction.

    Léger J, Delcour C, Carel JC

    The Journal of clinical endocrinology and metabolism 2022; (107(3)):836-846 doi:10.1210/clinem/dgab747.

    PMID: 34636892
  12. 12

    Complicated Relationship between Genetic Mutations and Phenotypic Characteristics in Transient and Permanent Congenital Hypothyroidism: Analysis of Pooled Literature Data.

    Long W, Zhou L, Wang Y, et al.

    International journal of endocrinology 2020; (2020()):6808517 doi:10.1155/2020/6808517.

    PMID: 32565793
  13. 13

    Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update-An ENDO-European Reference Network Initiative Endorsed by the European Society for Pediatric Endocrinology and the European Society for Endocrinology.

    van Trotsenburg P, Stoupa A, Léger J, et al.

    Thyroid : official journal of the American Thyroid Association 2021; (31(3)):387-419 doi:10.1089/thy.2020.0333.

    PMID: 33272083
  14. 14

    Neurodevelopmental Disorders, Cognitive Function, and Quality of Life in Children with Congenital Hypothyroidism in a Portuguese Population

    Leite-Almeida L, Curval R, Pais-Cunha I, et al.

    Journal of clinical research in pediatric endocrinology 2025; (17(4)):449-457 doi:10.4274/jcrpe.galenos.2025.2024-11-17.

    PMID: 40235218

This guide provides educational information about athyreosis in newborns. Always consult your pediatric endocrinologist for specific diagnostic testing, medication dosages, and treatment recommendations for your child.

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