Congenital hypothyroidism

Thyroid hormone deficiency present at birth

Congenital hypothyroidism (CH) is a condition where there is a lack of thyroid hormones in a baby from the moment of birth (1).

Thyroid hormones are essential for normal human growth and development, especially during the first few years of life. A universal newborn screening was developed four decades ago to help prevent the many consequences of CH.

Types of congenital hypothyroidism

CH affects 1 in 2,000 newborns. There are several variations of the conditions (2–7).

Based on the severity (4):

  • Severe congenital hypothyroidism — needs to be treated immediately
  • Mild congenital hypothyroidism

Based on the cause (4, 6, 7, 8–12):

Primary congenital hypothyroidism

  • 90% of cases
  • Caused by problems in thyroid development or an inability of the thyroid to produce enough hormones

Central congenital hypothyroidism

  • 10% of cases
  • Caused by pituitary gland dysfunction and low levels of TSH

Based on the duration (13,14):

  • Permanent – a lack of thyroid hormones that requires lifelong treatment
  • Transient

A temporary deficiency of thyroid hormones at birth, recovering to normal thyroid hormone levels within a few weeks to a few months. Most commonly it affects infants in the areas of iodine deficiency, exposure to thyroid blocking drugs before birth, high iodine, certain genetic mutations and liver dysfunction. It is very frequent, with 2 in 5 newborns having it.

How is CH diagnosed? (15, 16)

TSH levels between 6 and 15 mIU/L and decreased T4

fT4 levels:

  • Severe: when FT4 is <5 pmol/l
  • Moderate: when FT4 is 5 to 10 pmol/l
  • Light: when FT4 is 10 to 15 pmol/l

Signs and symptoms of congenital hypothyroidism

Most symptoms of CH are not typical to having an underactive thyroid, because while in utereo there are still some hormones coming from the mother’s placenta. These symptoms persist after birth (1, 17–19):

  • High birth weight
  • Umbilical hernia
  • Excessive sleeping
  • Unusually large tongue (macroglossia)
  • Cold or patchy and irregularly coloured skin (mottled skin)
  • Persistent jaundice (yellow skin or eyes)
  • Puffy face
  • Palpable goiter

Congenital hypothyroidism treatment

Levothyroxine is the first line treatment for CH. The recommended dose starts at 10 to 15 mcg per day. This is typically further adjusted individually.

Serum TSH and free T4 should be measured every 1–2 months in the first six months of a baby’s life, and every 3–4 months thereafter.

Treatment usually continues until three years of age, when doctors then assess how to continue (20, 21). Monitoring of child should continue in order to avoid overtreatment with T4 (22, 23).

How we write: our information is based on the results of peer reviewed studies using the National Library of Medicine platform. It is written by scientists and reviewed by external experts. If you believe we might have overseen crucial scientific information, please contact us at hello@boostthyroid.com

Disclaimer: This information is not intended to mitigate, prevent, treat, cure or diagnose any disease or condition. If you want to change your treatment, lifestyle, your diet, include supplements in your diet or have concerns about your health, please consult your doctor before trying new approaches.

References:

  1. Abduljabbar M, et al. Congenital hypothyroidism, 2012
  2. Ford G, et al. Screening for congenital hypothyroidism: A worldwide view of strategies, 2014
  3. Corbetta C, et al. A 7-year experience with low blood TSH cutoff levels for neonatal screening reveals an unsuspected frequency of congenital hypothyroidism (CH), 2009
  4. Deladoey J, et al. Is the incidence of congenital hypothyroidism really increasing? A 20-year retrospective population-based study in quebec, 2011
  5. Olivieri A, et al. Congenital hypothyroidism due to defects of thyroid development and mild increase of TSH at screening: Data from the Italian national registry of infants with congenital hypothyroidism, 2013
  6. Olivieri A, et al. Multiple factors influencing the incidence of congenital hypothyroidism detected by neonatal screening, 2015
  7. Wassner AJ, et al. Congenital hypothyroidism: Recent advances, 2015
  8. Fisher DA, et al. Screening for congenital hypothyroidism: Results of screening one million north american infants, 1979
  9. Hanna CE, et al. Detection of congenital hypopituitary hypothyroidism: Ten-year experience in the northwest regional screening program, 1986
  10. Persani L. Central hypothyroidism: Pathogenic, diagnostic, and therapeutic challenges, 2012
  11. Lanting CI, et al. Clinical effectiveness and cost-effectiveness of the use of the thyroxine/thyroxine-binding globulin ratio to detect congenital hypothyroidism of thyroidal and central origin in a neonatal screening program, 2005
  12. van Tijn DA, et al. Neonatal detection of congenital hypothyroidism of central origin, 2005
  13. Gaudino R, et al. Proportion of various types of thyroid disorders among newborns with congenital hypothyroidism and normally located gland: a regional cohort study, 2005
  14. Rastogi MV, et al. Congenital hypothyroidism, 2010
  15. Leger J, et al. European Society for Paediatric Endocrinology consensus guidelines on screening, diagnosis, and management of congenital hypothyroidism, 2014
  16. Segni M. Congenital Hypothyroidism, 2019
  17. LaFranchi SH. Hypothyroidism, 1979
  18. Delange F. Neonatal screening for congenital hypothyroidism: results and perspectives, 1997
  19. Grant DB, et al. Congenital hypothyroidism detected by neonatal screening: relationship between biochemical severity and early clinical features, 1992
  20. Lim G, et al. Early discontinuation of thyroxine therapy is possible in most very low-birthweight infants with hypothyroidism detected by screening, 2014
  21. Park ES, et al. Factors associated with permanent hypothyroidism in infants with congenital hypothyroidism, 2019
  22. Bongers-Schokking JJ, et al. Cognitive development in congenital hypothyroidism: is overtreatment a greater threat than undertreatment, 2013
  23. Alvarez M, et al. Episodes of overtreatment during the first six months in children with congenital hypothyroidism and their relationships with sustained attention and inhibitory control at school age, 2010

Photo: Unsplash; Design: VLM Health

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