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An Ex vivo Culture System to Study Thyroid Development
Published on: June 6, 2014
Clinical description of infants with congenital hypothyroidism and iodide organification defects
Paolo Cavarzere1, Mireille Castanet, Michel Polak
1Pediatric Endocrinology Unit, Hôpital Necker-Enfants Malades, AP-HP and University Paris Descartes, Faculty Necker, INSERM U845, Paris, France. paolocavarzere@yahoo.it
Insights
Congenital hypothyroidism with iodide organification defect (IOD) presents differently based on severity. Total IOD indicates severe disease, while partial IOD shows varied clinical features in children.
Area of Science:
- Endocrinology
- Pediatrics
- Genetics
Background:
- Congenital hypothyroidism (CH) is a common endocrine disorder in newborns.
- Iodide organification defect (IOD) is a specific cause of CH, impacting thyroid hormone synthesis.
- Understanding IOD phenotypes is crucial for diagnosis and management.
Purpose of the Study:
- To characterize the clinical phenotypes of children with congenital hypothyroidism due to iodide organification defect (IOD).
- To differentiate between total IOD (TIOD) and partial IOD (PIOD) based on clinical presentation and perchlorate discharge.
- To lay the groundwork for future genotype-phenotype correlation studies in IOD.
Main Methods:
- Retrospective analysis of 71 children diagnosed with CH and suspected IOD in Paris (1980-2006).
- Classification into TIOD (>90% perchlorate discharge) and PIOD (10-90% discharge).
- Clinical severity and features were compared between TIOD and PIOD groups.
Main Results:
- The incidence of IOD was 1:20,660 during 2003-2006.
- 61 children had PIOD, and 10 had TIOD.
- TIOD cases were clinically more severe than PIOD cases, which exhibited a wide spectrum of features. Transient hypothyroidism occurred in both groups.
Conclusions:
- Severe presentation in TIOD suggests a critical enzyme defect in iodide organification.
- The diverse clinical spectrum in PIOD implies multiple underlying mechanisms, including enzyme variations or iodine metabolism defects.
- Further research into genotype-phenotype correlations is warranted.
Aims:
To describe the phenotype of a large group of children with congenital hypothyroidism (CH) and iodide organification defect (IOD), suspected based on normal thyroid position and abnormal perchlorate discharge test, as first step of a project evaluating correlations between phenotypes and genotypes.
Methods:
71 children born in Paris between 1980 and 2006 were included. Two groups were defined according to perchlorate discharge: total IOD (TIOD) when the release was above 90% and partial IOD (PIOD) between 10 and 90%. Comparisons between groups were performed using SPSS 14.0 for Windows.
Results:
The incidence of IOD over the 2003-2006 period was 1:20,660. Of the 71 children, 61 had PIOD and 10 TIOD. Compared to PIOD, TIOD was characterized by greater clinical severity. A wide spectrum of clinical features was seen in the PIOD group. Evolution showed transient hypothyroidism in 10/61 patients with PIOD and 1/10 TIOD patients.
Conclusions:
Severe presentation in the majority of TIOD patients suggests dysfunction of a key iodide-organification enzyme. In contrast, the variety of clinical features in PIOD group suggests that diverse mechanisms may lead to PIOD, such as delayed or reduced activity of enzymes involved in hormonogenesis or defects in iodine storage and release.
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