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Abstract
Lingual thyroid is a rare developmental thyroid abnormality usually affecting females. It is often found in the region of the foramen caecum as a lingual thyroid at the base of the tongue in patients whose gland fails to descend. A 16-year-old female patient with severe hypothyroidism applied to our outpateint clinic. She was complaining from growth retardation, primary amenorrhea, weakness, decreases of school performance and short stature. No thyroid tissue was seen at the usual site with ultrasonography. Scintigrapy with 99mTC pertechnetate showed an ectopic functioning thyroid in the lingual area. CT scan showed a mass in the base of lingular region. The thyroid profile implied severe hypothroidism (free T3:0,142 ng/dl, free T4:0,741 ng/dl, and TSH:100 μIU/ml). Patient was accepted as primary hypothyrodism due to ectopic thyroid tissue (lingual thyroid) and substitution treatment with Lthyroxine was started at the dose of 2-3 μgr/kg. Surgical treatment did not consider because of patient was asymptomatic in terms of pressure. As a result we reported a rare cause of primary hypothyroidism due to ectopic thyroid gland (lingual) in a young female patient.