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PubMed This is a summary of 22 peer-reviewed journal articles Updated
Endocrinology

The Path to Answers: Screening and Testing for TDH

At a Glance

Familial thyroid dyshormonogenesis (TDH) is diagnosed through newborn screening for high TSH levels, followed by a thyroid ultrasound to check for an enlarged gland and genetic testing. Identifying the specific gene mutation helps determine if the condition is temporary or permanent.

The journey to diagnosing thyroid dyshormonogenesis (TDH) often feels like a “diagnostic odyssey.” It begins with a routine heel-prick test and moves through specialized imaging and genetic analysis to determine why your baby’s thyroid isn’t producing enough hormone [1][2].

The First Step: Newborn Screening (NBS)

In most countries, every newborn undergoes a screening test within 24 to 48 hours of birth. This test measures TSH (Thyroid-Stimulating Hormone), a signal from the pituitary gland (a small control center at the base of the brain) that tells the thyroid to wake up and work [1].

  • A “Flagged” Result: If the thyroid isn’t working properly, the pituitary gland “screams” at it by pumping out high levels of TSH. A high TSH on the screening test is the first indicator of congenital hypothyroidism [3][1].
  • The “Delayed TSH Rise”: Some babies—especially those born prematurely, those in the NICU, or those with specific genetic mutations like DUOX2—may have a normal TSH level on their very first test, only for it to rise days or weeks later [4][5]. This is why many hospitals perform a second screen for high-risk infants to ensure no diagnosis is missed [6][7].

Confirming the Diagnosis: The Follow-Up Tests

Once a screen is flagged, doctors use several tools to confirm the diagnosis and look for the specific cause (TDH).

1. Thyroid Ultrasound

This is a painless scan that uses sound waves to look at the thyroid gland in the neck. In TDH, the ultrasound typically shows a eutopic gland (a gland in its normal location) that may be enlarged, a condition known as a goiter [8][9]. This is a key finding that distinguishes TDH from other forms of hypothyroidism where the gland might be missing or in the wrong place [10][11].

2. Genetic Testing (NGS)

Modern medicine increasingly relies on Next-Generation Sequencing (NGS). This is a comprehensive blood test that looks at a panel of many different genes at once to find the exact “glitch” in the thyroid’s assembly line [12]. Identifying the specific gene is the most precise way to confirm TDH.

3. Perchlorate Discharge Test (PDT)

While less common today because of genetic testing, the PDT was historically a standard test for TDH. It involves a small, completely safe dose of a medical tracer (a very low-dose compound designed specifically for infants) followed by a medication (perchlorate) to see if the thyroid can “hold on” to iodine [13]. If the thyroid “discharges” the iodine too quickly, it confirms a specific defect in the hormone-making process [14][15].

Permanent vs. Transient Hypothyroidism

One of the most important reasons for a detailed diagnosis is to predict the future.

  • Transient (Temporary): Some forms of TDH, particularly those caused by certain DUOX2 mutations, are often transient [16][17]. The baby may need medication for the first few years of life, but their thyroid may eventually “catch up” and function normally on its own [18][19].
  • Permanent: Other mutations, such as those in the TPO or TG genes, usually mean the condition is permanent and will require lifelong thyroid hormone replacement [20].

Knowing the genetic cause allows your medical team to plan for a potential “trial off” medication at around age 3 to see if your child still needs treatment [21][22].

Common questions in this guide

Why was my baby's TSH level normal at birth but high later?
Some babies, especially those born prematurely or with specific genetic mutations, experience a delayed rise in TSH. Their initial newborn screening may look normal, which is why a second screening is often performed for high-risk infants to ensure no diagnosis is missed.
What does a thyroid ultrasound show in a baby with TDH?
In TDH, an ultrasound typically shows the thyroid gland in its normal location but enlarged. This enlargement is called a goiter and helps distinguish TDH from other forms of hypothyroidism where the gland might be missing or in the wrong place.
Will my baby need thyroid medication for life?
It depends on the specific genetic cause of the condition. Some forms of TDH are temporary, and the thyroid may eventually function normally on its own. Other genetic mutations cause permanent hypothyroidism that requires lifelong thyroid hormone replacement.
What is the perchlorate discharge test used for?
The perchlorate discharge test helps determine if the thyroid can hold onto iodine properly. While comprehensive genetic testing has made it less common today, this safe test can confirm a specific defect in the hormone-making process.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Was our baby's TSH elevation detected on the first newborn screen, or was it a 'delayed rise'?
  2. 2.Did the ultrasound show an enlarged thyroid gland (goiter), and what does that tell us about the cause?
  3. 3.Will we be ordering a Next-Generation Sequencing (NGS) genetic panel to identify the specific gene involved?
  4. 4.Based on the initial test results, do you suspect this might be a transient (temporary) form of hypothyroidism?
  5. 5.Is a perchlorate discharge test necessary for our baby, or will genetic testing provide enough information?

Questions For You

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References

References (22)
  1. 1

    Newborn Screening and Molecular Profile of Congenital Hypothyroidism in a Chinese Population.

    Yu B, Long W, Yang Y, et al.

    Frontiers in genetics 2018; (9()):509 doi:10.3389/fgene.2018.00509.

    PMID: 30420871
  2. 2

    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
  3. 3

    Evidence or enthusiasm? Why yields from UK newborn screening programmes for congenital hypothyroidism are increasing.

    Pollitt RJ

    Archives of disease in childhood 2016; (101(2)):120-3 doi:10.1136/archdischild-2015-309546.

    PMID: 26644400
  4. 4

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

    McGrath N, Hawkes CP, Mayne P, Murphy NP

    The Journal of pediatrics 2019; (205()):77-82 doi:10.1016/j.jpeds.2018.09.044.

    PMID: 30529133
  5. 5

    Avoiding the Overdiagnosis of Congenital Hypothyroidism in Premature Newborns.

    Grob F, Van Vliet G

    Pediatrics 2019; (144(2)) doi:10.1542/peds.2019-1706.

    PMID: 31311841
  6. 6

    Evaluation of the Congenital Hypothyroidism Detection Strategy in Extremely Preterm Infants in Western Andalusia.

    Rubio-Sánchez R, Núñez-Jurado D, Melguizo-Madrid E, et al.

    American journal of perinatology 2023; (40(13)):1421-1424 doi:10.1055/a-1627-0240.

    PMID: 34464987
  7. 7

    Congenital hypothyroidism with delayed thyroid-stimulating hormone elevation in premature infants born at less than 30 weeks gestation.

    Kaluarachchi DC, Colaizy TT, Pesce LM, et al.

    Journal of perinatology : official journal of the California Perinatal Association 2017; (37(3)):277-282 doi:10.1038/jp.2016.213.

    PMID: 27906195
  8. 8

    The mutation screening in candidate genes related to thyroid dysgenesis by targeted next-generation sequencing panel in the Chinese congenital hypothyroidism.

    Zhang RJ, Yang GL, Cheng F, et al.

    Clinical endocrinology 2022; (96(4)):617-626 doi:10.1111/cen.14577.

    PMID: 34374102
  9. 9

    Multi-parametric Ultrasound Evaluation of Pediatric Thyroid Dyshormonogenesis.

    Adaletli I, Bayramoglu Z, Caliskan E, et al.

    Ultrasound in medicine & biology 2019; (45(7)):1644-1653 doi:10.1016/j.ultrasmedbio.2019.03.004.

    PMID: 31031038
  10. 10

    Outcomes of newborns screened for congenital hypothyroidism in Turkey - a single center experience.

    Esen I, Eraslan N, Okdemir D

    Journal of pediatric endocrinology & metabolism : JPEM 2025; (38(1)):45-50 doi:10.1515/jpem-2024-0377.

    PMID: 39533791
  11. 11

    Evaluation of Transient or Permanent Congenital Hypothyroidism.

    Kurtoğlu S, Baştuğ O, Özdemir A

    Journal of clinical practice and research 2023; (45(4)):321-326 doi:10.14744/cpr.2023.32042.

    PMID: 41255433
  12. 12

    Targeted Next-Generation Sequencing of Congenital Hypothyroidism-Causative Genes Reveals Unexpected Thyroglobulin Gene Variants in Patients with Iodide Transport Defect.

    Bernal Barquero CE, Geysels RC, Jacques V, et al.

    International journal of molecular sciences 2022; (23(16)) doi:10.3390/ijms23169251.

    PMID: 36012511
  13. 13

    The Role of Nuclear Medicine in the Clinical Management of Benign Thyroid Disorders, Part 2: Nodular Goiter, Hypothyroidism, and Subacute Thyroiditis.

    Mariani G, Tonacchera M, Grosso M, et al.

    Journal of nuclear medicine : official publication, Society of Nuclear Medicine 2021; (62(7)):886-895 doi:10.2967/jnumed.120.251504.

    PMID: 33579801
  14. 14

    Late-onset dyshormonogenic goitrous hypothyroidism due to a homozygous mutation of the SLC26A7 gene: a case report.

    Sciarroni E, Montanelli L, Di Cosmo C, et al.

    Italian journal of pediatrics 2024; (50(1)):106 doi:10.1186/s13052-024-01672-3.

    PMID: 38812002
  15. 15

    Congenital Hypothyroidism: Role of Nuclear Medicine.

    Keller-Petrot I, Leger J, Sergent-Alaoui A, de Labriolle-Vaylet C

    Seminars in nuclear medicine 2017; (47(2)):135-142 doi:10.1053/j.semnuclmed.2016.10.005.

    PMID: 28237002
  16. 16

    Natural course of congenital hypothyroidism by dual oxidase 2 mutations from the neonatal period through puberty.

    Maruo Y, Nagasaki K, Matsui K, et al.

    European journal of endocrinology 2016; (174(4)):453-63 doi:10.1530/EJE-15-0959.

    PMID: 26742565
  17. 17

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

    Zheng Z, Yang L, Sun C, et al.

    Annals of translational medicine 2020; (8(24)):1649 doi:10.21037/atm-20-7165.

    PMID: 33490161
  18. 18

    Next-generation sequencing analysis of DUOX2 in 192 Chinese subclinical congenital hypothyroidism (SCH) and CH patients.

    Fu C, Luo S, Zhang S, et al.

    Clinica chimica acta; international journal of clinical chemistry 2016; (458()):30-4.

    PMID: 27108200
  19. 19

    Compound Heterozygous Mutations in the DUOX2/DUOXA2 Genes Cause Congenital Hypothyroidism.

    Zheng X, Ma SG, Guo ML, et al.

    Yonsei medical journal 2017; (58(4)):888-890 doi:10.3349/ymj.2017.58.4.888.

    PMID: 28541007
  20. 20

    Mutation spectra and genotype‑phenotype analysis of congenital hypothyroidism in a neonatal population.

    Huang X, Shao Q, Weng S, et al.

    Biomedical reports 2025; (22(2)):30 doi:10.3892/br.2024.1908.

    PMID: 39720292
  21. 21

    Gene mutations in children with permanent congenital hypothyroidism in Yunnan, China.

    Gong Y, Zhang Y, Liu F, et al.

    Zhejiang da xue xue bao. Yi xue ban = Journal of Zhejiang University. Medical sciences 2022; (51(3)):306-313 doi:10.3724/zdxbyxb-2022-0199.

    PMID: 36207832
  22. 22

    Double variants in TSHR and DUOX2 in a patient with hypothyroidism: case report.

    Sasivari Z, Szinnai G, Seebauer B, et al.

    Journal of pediatric endocrinology & metabolism : JPEM 2019; (32(11)):1299-1303.

    PMID: 31541602

This page explains screening and diagnostic testing for familial thyroid dyshormonogenesis for educational purposes only. Always consult your pediatrician or pediatric endocrinologist to interpret your baby's specific screening results.

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