Thyroid agenesis

Thyroid agenesis is a rare congenital condition characterized by the absence of the thyroid gland at birth. It is one of the causes of congenital hypothyroidism, a condition that can lead to physical and mental growth retardation if not treated promptly.

Etiology

The exact cause of thyroid agenesis is unknown. However, it is believed to be due to genetic mutations or environmental factors that affect the migration of thyroid precursor cells during embryonic development. Some studies have suggested a link with mutations in the TTF-2 (Thyroid Transcription Factor 2) gene, but this has not been conclusively proven.

Clinical Presentation

Infants with thyroid agenesis are usually asymptomatic at birth. Symptoms of hypothyroidism may develop over time and can include poor growth, delayed development, constipation, and a hoarse cry. Severe cases can lead to cretinism, a condition characterized by severe physical and mental retardation.

Diagnosis

Diagnosis of thyroid agenesis is usually made through newborn screening tests for hypothyroidism. These tests measure the levels of thyroid-stimulating hormone (TSH) and thyroxine (T4) in the blood. High levels of TSH and low levels of T4 suggest hypothyroidism. The diagnosis can be confirmed by a thyroid scan which shows the absence of the thyroid gland.

Treatment

Treatment for thyroid agenesis involves lifelong replacement therapy with synthetic thyroid hormone (levothyroxine). Regular monitoring of thyroid function tests is necessary to ensure adequate dosing.

Prognosis

With early diagnosis and treatment, children with thyroid agenesis can lead normal lives. However, lifelong monitoring and treatment are necessary to prevent complications.

See Also

• Thyroid dysgenesis
• Thyroid ectopy
• Congenital hypothyroidism

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