Congenital hypothyroidism plays a role in the etiology of thyroid dysgenesis at 80-85%. However, rarely, triode agenesis can cause congenital hypothyroidism. If thyroid hormone therapy is not initiated in the first two months of life, congenital hypothyroidism can cause serious neurological, mental, and motor damage. In this case, we aimed to present the case of thyroid agenesis which is followed up due to hypothyroidism in adulthood.

Thyroidagenesis, Hypothyroidism.

Congenital hypothyroidism plays a role in the etiology of thyroid dysgenesis at 80-85%. However, rarely, triode agenesis can cause congenital hypothyroidism. If thyroid hormone therapy is not initiated in the first two months of life, congenital hypothyroidism can cause serious neurological, mental, and motor damage. In this case, we aimed to present the case of thyroid agenesis which is followed up due to hypothyroidism in adulthood.

Thyroidagenesis, Hypothyroidism.

Thyroid hemiagenesis and bilobalr agenesis are rare thyroid diseases. It was first reported by Marshall [1] in 1985. When thyroid agenesis is detected in childhood, the hemiagenesis may not be detected until asymptomatic hypothyroidism develops.

An 18-year-old female patient was treated with levothyroxine for hypo thyroidism after birth. On physical examination, thyroid nonpalpable, pulse: 105/min, levothyroxine 300 mg/day was used in our clinic. Theiatrogenic thyrotoxicos is detected in the thyroid function tests was reduced to 150 mg of the patient’s intake. Thyroid ultrasonography (Figure 1) did not reveal thyroid tissue in the thyroidloin. Levothyroxine dose was regulated to the out patient clinic.

Thyroid agenesis is a rare congenital anomaly that occurs as a result of defects (genetic factors) that occur in the thyroid tissue during embryological development. It can usually be diagnosed with complaints such as a decrease in reflexes in childhood, difficulty in nutrition, constipation, and growth retardation. Infemales, it is 3 times more common than males [2]. Many variations in thyroid tissue have been reported in the literature. The thyroid gland between the tongue root and the thyroidloju can remain in the thyroid gland starting from the epigastrium in the level of the pharynx from embryogenesis. During the seventh week, the thyroid gland anatomically resides in its own region. Sometimes, when hemiagenesis develops in the lateral migration failure of cells, lobulation defects may result in environmental and geneticdisorders [2-4].

Thyroid agenesis is a rare congenital disease. It can cause severe lifethreatening conditions when not treated from childhood.