[Thyroid dysfunction in the newborn].

Maria Vítor Campos; Beatriz Campos

PubMed · 14750283

[Thyroid dysfunction in the newborn].

Abstract

The authors refer to congenic hypothyroidism, hypotyroxinemia in premature new-borns, thyroid dysfunction, congenic thyrotoxicosis, breastfeeding, composed anti-thyroid drugs and children nutrition based on iodine. Concerning to the fetus and new-born thyroid dysfunction, it's very important to make an early diagnosis in order to avoid later complications. Several studies revealed that the different types of composed anti-thyroid drugs can induce pregnant woman choice.

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Congenital Hypothyroidism Humans Hypothyroidism Infant, Newborn Iodine Thyroid Diseases English Abstract Journal Article

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Maria Vítor Campos, Beatriz Campos. [Thyroid dysfunction in the newborn].. https://pubmed.ncbi.nlm.nih.gov/14750283/

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Missense mutation in the transcription factor NKX2-5: a novel molecular event in the pathogenesis of thyroid dysgenesis.

CONTEXT: Congenital hypothyroidism (CH) is a common endocrine disorder with an incidence of 1:3000-4000 at birth. In 80-85% of cases, CH is caused by defects in thyroid organogenesis, resulting in absent, ectopically located, and/or severely reduced gland [thyroid dysgenesis (TD)]. Mutations in genes controlling thyroid development have demonstrated that in a few cases, TD is a Mendelian trait. However, accumulating evidence supports the view that the genetics of TD are complex, possibly with a polygenic/multifactorial basis. A higher prevalence of congenital heart disease has been documented in children with CH than in the general population. Such an association suggests a possible pathogenic role of genes involved in both heart and thyroid development. NKX2-5 encodes a homeodomain-containing transcription factor with a major role in heart development, and mutations affecting this gene have been reported in individuals with congenital heart disease. OBJECTIVE: In the present work we investigated the possible involvement of NKX2-5 mutations in TD. RESULTS: Our results indicate that Nkx2-5(-/-) embryos exhibit thyroid bud hypoplasia, providing evidence that NKX2-5 plays a role in thyroid organogenesis and that NKX2-5 mutations contribute to TD. NKX2-5 mutational screening in 241 patients with TD allowed the identification of three heterozygous missense changes (R25C, A119S, and R161P) in four patients with TD. Functional characterization of the three mutations demonstrated reduced DNA binding and/or transactivation properties, with a dominant-negative effect on wild-type NKX2-5. CONCLUSION: Our results suggest a previously unknown role of NKX2-5 in the pathogenesis of TD.

Congenital Hypothyroidism↗

PubMed2005

Rate of recalls in congenital hypothyroidism based upon a regional survey in Isfahan, Iran, using serum T4 and TSH analyses: comparison of two different recall methods.

AIMS: To evaluate and compare the recall rate in congenital hypothyroidism screening project in Isfahan, first using an approach involving measures of both TSH and T4 and then using TSH alone. METHODS: From June 2002 to January 2005, serum TSH and T4 level of referred neonates were measured at 3rd to 7th day of birth through venous sampling. If neonates' serum TSH was >20 mIU/l or T4 was <6.5 microg/dl by the first protocol, or TSH was >20 mIU/l by the second protocol, they were recalled. TSH and T4 were measured using an immunoradiometric assay and radioimmunoassay, respectively. Neonates with TSH > 10 and T4 < 6.5 on their second measurement were considered as congenitally hypothyroid. RESULTS: Serum T4 and TSH of 29,425 neonates by first and 57,235 neonates by second recall approach were measured. Recall rate was higher in the first protocol (2.2% vs. 0.6%, p < 0.05). Most of the recalled neonates in the first protocol were recalled for low T4 level (p < 0.05). The prevalence of CH was 1 in 350 livebirths. CONCLUSION: Although the recall rate was in the acceptable range by either approach, the TSH alone protocol seems to be a more sensitive and practical approach with the least recall burden and considering the high prevalence of CH in our region merit adaptation of widespread screening for CH using TSH measurements from heel stab blood spotted on filter paper.

Congenital Hypothyroidism↗

PubMed2005

[Left ventricular function in congenital hypothyroidism neonates before and after thyroxine substitution therapy].

OBJECTIVE: To evaluate left the systolic and diastolic functions in neonates with congenital hypothyroidism (CH) as well as the effect of thyroxine substitution therapy on left ventricular function and its correlation with thyroid hormones serum levels. METHODS: M-mode echocardiography was used to examine the left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS), pulse wave Doppler was used to examine the peak early diastolic mitral inflow velocity (E(m)) and peak late diastolic mitral inflow velocity (A(m)), quantitative tissue velocity imaging (QTVI) was used to examine the systolic peak mitral annular velocity (s(m)), early diastolic peak mitral annular velocity (E(m)), and the late diastolic peak mitral annular velocity (a(m)), and tissue tracking imaging (TTI) was used to detect the systolic mitral annular displacement (MAD) in 40 neonates with congenital hypothyroidism aged 15-28 days before and after 1-month levothyroxine substitution treatment. Thirty normal neonates were used as controls. Chemiluminescent immunoassay was used to measure the TT(3), TT(4) and TSH levels. Correlation analysis was also made between the ventricular function parameters and the serum TT(3), TT(4), and TSH levels. RESULTS: The left systolic function parameters (LVEF, s(m), MAD, E(m) and e(m)) was 0.61 +/- 0.08, 2.60 cm/s +/- 0.60 cm/s, 0.29 cm +/- 0.06 cm, 0.59 m/s +/- 0.12 m/s and 2.72 cm/s +/- 1.43 cm/s respectively, in CH group, and 0.67 +/- 0.06, 3.25 cm/s +/- 0.51 cm/s, 0.41 cm +/- 0.08 cm, 0.72 m/s +/- 0.11 m/s and 4.51 cm/s +/- 1.23 cm/s in control group (P < 0.01). Left function in CH neonates before treatment were all lower than those of the controls (P < 0.01), which significantly increase after 1-months L-T(4) substitution therapy, 0.69 +/- 0.05, 3.46 cm/s +/- 0.64 cm/s, 0.45 cm +/- 0.08 cm, 0.82 m/s +/- 0.17 m/s and 5.09 cm/s +/- 1.37 cm/s, (P < 0.01). Those parameters were positively correlated with TT(4) serum levels (P < 0.01), and were negatively correlated with TSH (all P < 0.01). In particular, MAD, sm, E(m), and em were highly correlated with serum TT(4) and TSH (r = 0.667, 0.538, 0.478, and 0.599 respectively, all P < 0.001;and r = -0.670, -0.521, -0.490, and -0.583 respectively, all P < 0.001). CONCLUSION: Neonates with CH have lower left systolic and diastolic functions. Early L-T(4) substitution therapy can reverse these changes.

Congenital Hypothyroidism↗