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

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.