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BRIEF COMMUNICATION
Year : 2014  |  Volume : 18  |  Issue : 7  |  Page : 97-99

Agenesis and not ectopia is common in North Indian children with thyroid dysgenesis


1 Department of Pediatrics, Pediatric Endocrinology and Diabetes Unit, Postgraduate Institute of Medical Education and Research, Chandigarh, India
2 Pediatric Endocrinology Unit, Postgraduate Institute of Medical Education and Research, Chandigarh, India
3 Department of Nuclear Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India
4 Department of Radiodiagnosis Postgraduate Institute of Medical Education and Research, Chandigarh, India
5 Department of Endocrinology, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Date of Web Publication20-Nov-2014

Correspondence Address:
Devi Dayal
Department of Pediatrics, Pediatric Endocrinology and Diabetes Unit, Advanced Pediatrics Center, Postgraduate Institute of Medical Education and Research, Chandigarh - 160 012
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/2230-8210.145080

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   Abstract 

Context: Ectopic Thyroid Gland (ETG) is known to be the most common form of thyroid dysgenesis in children with permanent congenital hypothyroidism (CH). Recent reports indicate that agenesis or hypoplasia of thyroid gland may be commoner as compared to ETG in thyroid dysgenesis (TD). There is limited information available on the proportion of different variants of TD in Indian children. Aim: To characterize the different TD variants in a cohort of North Indian children with TD. Settings and Design: Endocrinology Unit of a large Multispecialty Pediatrics Center located in North India. Retrospective review of clinical records of children with CH due to TD diagnosed between April 2004 and March 2014. Results: Diagnoses of TD in 94 children (48 boys and 46 girls) were based on combined scanning with high-resolution ultrasonography, and technetium-99m pertechnetate thyroid scintigraphy. Thyroid agenesis, ectopia and hypoplasia were diagnosed in 74 (78.7%), 14 (14.8%) and 6 (6.4%) patients respectively. The mean initial serum total T4 and thyroid stimulating hormone concentrations at diagnosis were 3.03 ± 2.88 μg/dL (range 0.01-8.9) and 284.52 ± 300.67 mIU/L (range 10.03-1159.0) respectively. Patients with ETG were older at the time of diagnosis as compared to patients with hypoplasia or ectopia. The mean duration of follow-up was 3.7 ± 2.85 years (range 3 months-10 years). Conclusions : Thyroid agenesis was the most common form of TD in our children with permanent CH. Hypoplasia and ectopia were uncommon. Female preponderance, noted in many previous reports, was not seen in our patients with TD.

Keywords: Agenesis, congenital hypothyroidism, ectopic thyroid gland, thyroid dysgenesis


How to cite this article:
Dayal D, Sindhuja L, Bhattacharya A, Sodhi KS, Sachdeva N. Agenesis and not ectopia is common in North Indian children with thyroid dysgenesis. Indian J Endocr Metab 2014;18, Suppl S1:97-9

How to cite this URL:
Dayal D, Sindhuja L, Bhattacharya A, Sodhi KS, Sachdeva N. Agenesis and not ectopia is common in North Indian children with thyroid dysgenesis. Indian J Endocr Metab [serial online] 2014 [cited 2019 Sep 19];18, Suppl S1:97-9. Available from: http://www.ijem.in/text.asp?2014/18/7/97/145080


   Introduction Top


Thyroid dysgenesis (TD) is the most common cause of permanent congenital hypothyroidism (CH), and includes athyreosis, hypoplasia, hemiagenesis and ectopic thyroid gland (ETG). [1]

Worldwide, ETG is the most common form of TD with a prevalence of about 1/100,000-300,000 persons and 1/4000-8000 patients with thyroid disease. [2],[3],[4],[5] Some recent studies indicate that the predominant form of TD is agenesis or hypoplasia. [6],[7] There is limited information on the proportion of each TD variant in Indian children with CH. A previous study suggested agenesis and/or hypoplasia to be more common as compared to ETG. [8] Another study has only reported the clinical spectrum of ETG. [9] We aimed to determine the spectrum of TD in children diagnosed with permanent CH at our center.


   Materials and Methods Top


A record review of children with permanent CH, who attended our hospital between April 2004 and March 2014, was performed. The diagnosis of hypothyroidism was based on low serum total thyroxine (T4), and elevated serum thyroid stimulating hormone (TSH) levels according to reference ranges. [10] Children with subclinical hypothyroidism, transient hypothyroidism, autoimmune thyroiditis or syndromic diagnoses were excluded. Serum total T4, TSH and anti-thyroid peroxidase antibodies concentrations were measured by Electrochemiluminescence immunoassay on Elecsys 2010 analyzer using specific kits (Roche Diagnostics, Germany).

The diagnosis of TD was based on findings of the technetium-99m (99mTc) pertechnetate thyroid scintiscan, and thyroid ultrasonograms done routinely at the time of the initial evaluation of CH. Scintigraphy was performed using a gamma camera fitted with low energy high-resolution collimator (Siemens, Germany). Static planar images of head, neck and chest region were acquired in the anterior projection 20 min after intravenous injection of 74-111 MBq of 99mTc pertechnetate. Thyroid agenesis was defined as the absence of tracer uptake in the normal gland location while visualization of a single lobe was regarded as hemiagenesis. Mild to moderate tracer uptake in small, ill-defined focus in the normal gland location was taken as hypoplasia, while any focal uptake in midline from tongue to the suprasternal notch in absence of the normal gland was identified as ETG.

Ultrasonography was performed in supine position with hyperextended neck using ultrasound machine equipped with a 3-12 MHz high frequency linear transducer, 3-8 MHz sector array and 2-5 MHz convex array probes (Philips HD11XE). Images were obtained in transverse, and longitudinal planes; and anterior cervical area was systematically viewed for presence of ectopic thyroid tissue. Agenesis was defined as the absence of gland in the normal location. Absence of gland in the normal location and presence of some thyroid tissue in the midline was labeled as ETG. Hemiagenesis was defined as the absence of one lobe. Linear dimensions of lobes and isthmus were measured, and thyroid volume (Tvol) was calculated for each lobe using the algorithm: Craniocaudal*lateromedial*anteroposterior diameter*0.5. Total Tvol was calculated by adding the volumes of lobes and ignoring the isthmus volume. Hypoplasia was defined as Tvol <3 rd percentiles of normative data in a reference population. [11]


   Results Top


Complete information was available in 94 children (48 boys and 46 girls) with TD. Their mean age at diagnosis was 2.45 ± 2.69 years (range 2 months-11 years). Based on the results of combined scanning, majority (74 patients, 78.7%) were diagnosed as agenesis. Hypoplasia was noted in 6 (6.4%) while 14 (14.8%) patients were labeled as ETG. The mean initial serum total T4 and TSH concentrations at diagnosis were 3.03 ± 2.88 μg/dL (range 0.01-8.9) and 284.52 ± 300.67 mIU/L (range 10.03-1159.0) respectively. The mean duration of follow up was 3.7 ± 2.85 years (range 3 months-10 years).

The mean age of patients at diagnosis of agenesis was significantly, lower as compared to patients with hypoplasia or ectopia [Table 1]. The mean total T4 and TSH concentrations as well as a requirement of thyroxine dose were similar in the 3 TD variants.
Table 1: Comparison of clinical and laboratory parameters in different TD variants

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   Discussion Top


The predominant form of TD noted in our patients was agenesis similar to a recent study. [6] Another study from Turkey found an increased incidence of thyroid hypoplasia but attributed this to noninclusion of thyroid scintigraphy. [7] Indian data obtained during 1990s suggested that agenesis and/or hypoplasia was the predominant form of TD in children belonging to iodine deficient regions, and postulated that iodine deficiency may lead to TD. [8] Iodine deficiency contributing to TD seems unlikely, as our study population belongs to a nonendemic area. [12],[13]

The reasons for a different spectrum of TD in our patients are presently unclear. Although mutations associated with TD are detected in only 2% of all cases, the candidate genes probably determine the TD form. [14] The transcription factors PAX8, NKX2-1, FOXE1, NKX2-5 and PAX9 are considered as candidate genes for ETG while TSH receptor (TSHR) gene mutations result in hypoplasia. [1],[15] Probably our patients have TSHR mutations more than the other mutations but in the absence of molecular investigations, this is only a speculation. The younger age of our patients might also have decreased the percentage of ETG as this is more commonly diagnosed between 10 and 20 years of age. [2] Since, we had employed both scintigraphy and high-resolution ultrasonography, it is unlikely that the characterization of TD variants in our patients was not exact. Combined scanning is considered more informative than single scanning in CH. [3],[16]

Similar to our findings, absence of hemiagenesis has been noted in previous large cohorts of TD. [3],[5] Higher prevalence is attributed to genetic factors resulting from frequent parental consanguinity. [4],[6],[7]

Similar to a previous study, we did not find a higher prevalence of TD in girls. [7] This is in contrast with several reports that suggest female preponderance. [3],[8],[17],[18],[19] The low prevalence of ETG in our cohort might partly explain the observed sex ratio as female preponderance is commoner in ETG than athyreosis. [9],[20]


   Conclusion Top


Majority of our patients with TD had agenesis. Hypoplasia and ectopia were uncommon, and hemiagenesis was not noted in any patient. The prevalence of TD was similar in boys and girls. This is the first study from our country to document the morphological spectrum of TD based on combined scanning.

 
   References Top

1.Brown RS, Demmer LA. The etiology of thyroid dysgenesis-still an enigma after all these years. J Clin Endocrinol Metab 2002;87:4069-71.  Back to cited text no. 1
    
2.Noussios G, Anagnostis P, Goulis DG, Lappas D, Natsis K. Ectopic thyroid tissue: Anatomical, clinical, and surgical implications of a rare entity. Eur J Endocrinol 2011;165:375-82.  Back to cited text no. 2
    
3.Tamam M, Adalet I, Bakir B, Türkmen C, Darendeliler F, Bas F, et al. Diagnostic spectrum of congenital hypothyroidism in Turkish children. Pediatr Int 2009;51:464-8.  Back to cited text no. 3
    
4.Ramos HE, Nesi-França S, Boldarine VT, Pereira RM, Chiamolera MI, Camacho CP, et al. Clinical and molecular analysis of thyroid hypoplasia: A population-based approach in southern Brazil. Thyroid 2009;19:61-8.  Back to cited text no. 4
    
5.Bekhit OE, Yousef RM. Permanent and transient congenital hypothyroidism in Fayoum, Egypt: A descriptive retrospective study. PLoS One 2013;8:e68048.  Back to cited text no. 5
    
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7.Kirmizibekmez H, Güven A, Yildiz M, Cebeci AN, Dursun F. Developmental defects of the thyroid gland: Relationship with advanced maternal age. J Clin Res Pediatr Endocrinol 2012;4:72-5.  Back to cited text no. 7
    
8.Shankar SM, Menon PS, Karmarkar MG, Gopinath PG. Dysgenesis of thyroid is the common type of childhood hypothyroidism in environmentally iodine deficient areas of north India. Acta Paediatr 1994;83:1047-51.  Back to cited text no. 8
    
9.Gopal RA, Acharya SV, Bandgar T, Menon PS, Marfatia H, Shah NS. Clinical profile of ectopic thyroid in Asian Indians: A single-center experience. Endocr Pract 2009;15:322-5.  Back to cited text no. 9
    
10.The Association of Clinical Biochemistry, 2006. UK guidelines for the use of thyroid function tests, from British thyroid association's website. Available from: http://www.british-thyroid-association.org. [Last accessed on 2014 Aug 14].  Back to cited text no. 10
    
11.Chanoine JP, Toppet V, Lagasse R, Spehl M, Delange F. Determination of thyroid volume by ultrasound from the neonatal period to late adolescence. Eur J Pediatr 1991;150:395-9.  Back to cited text no. 11
    
12.Kapil U. Successful efforts toward elimination iodine deficiency disorders in India. Indian J Community Med 2010;35:455-68.  Back to cited text no. 12
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13.Das S, Bhansali A, Dutta P, Aggarwal A, Bansal MP, Garg D, et al. Persistence of goitre in the post-iodization phase: Micronutrient deficiency or thyroid autoimmunity? Indian J Med Res 2011;133:103-9.  Back to cited text no. 13
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14.Narumi S, Muroya K, Asakura Y, Adachi M, Hasegawa T. Transcription factor mutations and congenital hypothyroidism: Systematic genetic screening of a population-based cohort of Japanese patients. J Clin Endocrinol Metab 2010;95:1981-5.  Back to cited text no. 14
    
15.Park SM, Chatterjee VK. Genetics of congenital hypothyroidism. J Med Genet 2005;42:379-89.  Back to cited text no. 15
    
16.Perry RJ, Maroo S, Maclennan AC, Jones JH, Donaldson MD. Combined ultrasound and isotope scanning is more informative in the diagnosis of congenital hypothyroidism than single scanning. Arch Dis Child 2006;91:972-6.  Back to cited text no. 16
    
17.Eugène D, Djemli A, Van Vliet G. Sexual dimorphism of thyroid function in newborns with congenital hypothyroidism. J Clin Endocrinol Metab 2005;90:2696-700.  Back to cited text no. 17
    
18.Waller DK, Anderson JL, Lorey F, Cunningham GC. Risk factors for congenital hypothyroidism: An investigation of infant's birth weight, ethnicity, and gender in California, 1990-1998. Teratology 2000;62:36-41.  Back to cited text no. 18
    
19.Law WY, Bradley DM, Lazarus JH, John R, Gregory JW. Congenital hypothyroidism in Wales (1982-1993): Demographic features, clinical presentation and effects on early neurodevelopment. Clin Endocrinol (Oxf) 1998;48:201-7.  Back to cited text no. 19
    
20.Devos H, Rodd C, Gagné N, Laframboise R, Van Vliet G. A search for the possible molecular mechanisms of thyroid dysgenesis: Sex ratios and associated malformations. J Clin Endocrinol Metab 1999;84:2502-6.  Back to cited text no. 20
    



 
 
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