The presence or absence of a thyroid gland in infants can be determined by measuring thyroid function and ultrasound of the thyroid gland. Generally, infants have a thyroid gland, while some extremely rare infants may have a congenital thyroid deficiency. The thyroid gland, as an important endocrine gland of the body, plays an important role in growth and development, temperature regulation, and metabolism. The presence or absence of thyroid gland can be determined by ultrasound of the thyroid gland, measurement of thyroid function, and determination of symptoms. 1. Ultrasound of the thyroid gland: It is possible to find out the condition of thyroid nodules, texture, size, and blood flow. 2. Measurement of thyroid function: If an infant does not have a thyroid gland, hypothyroidism is usually seen as a decrease in T3 and T4, and an increase in TSH. 3. Determination of symptoms: If the infant does not have a thyroid gland, hypothyroidism is usually present, with hypometabolic symptoms such as weight gain, memory loss, and cretinism. It can be treated by taking medication such as thyroid tablets, but the use of medication should be under the guidance of a doctor.