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Thyroid Disorders


generation defects (due to mutations in DUOX2 or DUOXA2), Pendred syndrome, thyroglobulin defects and defects in iodotyrosine deiododinase (as a result of mutations in DEHAL1 or SECISBP2).


Mutations in the genes that encode the TSH receptor or G-protein may cause resistance to TSH binding or signalling, and this is another subtype of genetic CH.


There are no specific guidelines for monitoring the genetic conditions associated with hypothyroidism, but establishing the diagnosis would allow to classify the child as having persistent hypothyroidism, which in turn would avoid unnecessary trial periods off treatment and testing. It is also important to identify children with these gene mutations so that families can receive genetic counselling and siblings can be tested.


From Guidelines to Practice


The current clinical practice of 143 members of the British Society for Paediatric Endocrinology and Diabetes was


1. Fisher DA, Foley BL, Early treatment of congenital hypothyroidism, Pediatrics, 1989; 83:785–9.


2. American Academy of Pediatrics, Rose SR; Section on Endocrinology and Committee on Genetics, American Thyroid Association, Brown RS; Public Health Committee, Lawson Wilkins Pediatric Endocrine Society, Foley T, et al., Update of newborn screening and therapy for congenital hypothyroidism, Pediatrics, 2006;117:2290–303.


3. Heyerdahl S, Oerbeck B, Congenital hypothyroidism: developmental outcome in relation to levothyroxine treatment variables, Thyroid, 2003;13:1029–38.


4. Rastogi MV, LaFranchi SH, Congenital hypothyroidism, Orphanet J Rare Dis, 2010;5:17.


5. Hertzberg V, Mei J, Therrell BL, Effect of laboratory practices on the incidence rate of congenital hypothyroidism, Pediatrics, 2010;125(Suppl. 2):S48–53.


6. Mitchell ML, Hsu HW, Sahai I, Massachusetts Pediatric Endocrine Work Group, The increased incidence of congenital hypothyroidism: fact or fancy? Clin Endocrinol (Oxf), 2011;75:806–10.


7. Mandel SJ, Hermos RJ, Larson CA, et al. Atypical hypothyroidism and the very low birthweight infant, Thyroid,


2000;10:693–5.


8. Bijarnia S, Wilcken B, Wiley VC, Newborn screening for congenital hypothyroidism in very-low-birth-weight babies: the need for a second test, J Inherit Metab Dis, 2011;34:827–33.


9. Woo HC, Lizarda A, Tucker R, et al., Congenital hypothyroidism with a delayed thyroid-stimulating hormone elevation in very premature infants: incidence and growth and developmental outcomes, J Pediatr, 2011;158:538–42.


10. Working Group on Neonatal Screening of the European Society for Paediatric Endocrinology, Revised guidelines for neonatal screening programmes for primary congenital hypothyroidism, Horm Res, 1999;52:49–52.


11. Jones JH, Gellén B, Paterson WF, et al., Effect of high versus low initial doses of L-thyroxine for congenital hypothyroidism on thyroid function and somatic growth, Arch Dis Child, 2008;93:940–4.


12. Balhara B, Misra M, Levitsky LL, Clinical monitoring guidelines for congenital hypothyroidism: laboratory outcome data in the first year of life, J Paediatrics, 2011;58:532–7.


A recent study in the UK compared the national practice of early management of CH with the latest available European and UK guidelines.17


assessed using a questionnaire. The survey investigated the timing of the initial and first post-treatment visits, L-T4 preparation, initial dose, and clinical aims in terms of biochemical outcomes. The study found gaps between the practice and guidelines in key aspects of the management of CH. For example, 26 % of responders chose an initial L-T4 dose of <10 µg/kg/day, and 20 % of respondents scheduled the first post-treatment visit more than 14 days after initiation of treatment – both in contradiction with the recommendations in the guidelines. These numbers emphasise the importance of promulgating guidelines among providers to ensure optimal patient care.


Summary


Adequate and timely follow-up of CH is critical for optimising outcomes. Guidelines for follow-up should be revised frequently to accommodate new information. Presently, there are differences between the guidelines of the AAP, ESPE and UK thyroid study groups. Further differences arise in practice due to a lack of adherence to the recommendations. For optimum patient care, it would be important to ensure that uniform evidence-based guidelines are developed and that they are followed in practice. n


13. Baloch Z, Carayon P, Conte-Devolx B, et al., Guidelines Committee, National Academy of Clinical Biochemistry, Laboratory medicine practice guidelines. Laboratory support for the diagnosis and monitoring of thyroid disease, Thyroid, 2003;13:3–126.


14. American Academy of Pediatrics (AAP) Section on Endocrinology and Committee on Genetics, and American Thyroid Association Committee on Public Health, Newborn screening for congenital hypothyroidism: recommended guidelines, Pediatrics, 1993;91:1203–9.


15. Escobar-Morreale HF, Botella-Carretero JI, Escobar del Rey F, et al., REVIEW: Treatment of hypothyroidism with combinations of levothyroxine plus liothyronine, J Clin Endocrinol Metab, 2005;90:4946–54.


16. Akcay T, Turan S, Guran T, et al., T4 plus T3 treatment in children with hypothyroidism and inappropriately elevated thyroid-stimulating hormone despite euthyroidism on T4 treatment, Horm Res Paediatr, 2010;73:108–14.


17. Jones JH, Donaldson MD, Audit of initial management of congenital hypothyroidism in the United Kingdom – comparison of UK practice with European and UK guidelines, J Pediatr Endocrinol Metab, 2009;22:1017–25.


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EUROPEAN ENDOCRINOLOGY


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