A one year old child preents with short stature, lethargy, & constipation. Clinical examinaton shows a palpable goiter. Laboratory investigations revealed a low T4 and elevated TSH which of the following is the most likely diagnosis.

This child has :- Thyroid swelling Low T4 & High TSH Abnormal weight gain and poor activities All these suggests the diagnosis of congenital hypothyroidism due to thyroid disorder (In hypothalamic diseases,TSH levels will be low). The most common cause of non - endemic congenital hypothyroidism is thyroid dysgenesis. In endemic regions :- Most common cause of congenital hypothyroidism is iodine deficiency in intrauterine and neonatal period (world wide). In non-endemic regions :- Most common cause of congenital hypothyroidism is thyroid dysgenesis. However, in thyroid dysgenesis, thyroid gland does not enlarge to produce palpable goitre. So, this option is excluded. Dyshormogensis is an uncommon cause of congenital goitrous hypothyroidism and account only about 10-15% of cases of congenital hypothyroidism. It results from a deficiency of one or more enzymes (most commonly, thyroid peroxidase) involved in thyroid hormone synthesis or secretion.