Thyroid Disorders are divided into anatomical and functional disorders. Anatomical thyroid disorders are related to the size of the thyroid and concern goitres, nodules, and neoplasms. Functional thyroid disorders involve the function and abnormal production of thyroid hormones: hyperthyroidism and hypothyroidism.

Girls are usually more prone to these problems due to hormonal changes in puberty. If they are not diagnosed early, thyroid disorders can affect the physical and mental development of the child.

Thyroid Disorders: What is the function of the thyroid?

The thyroid is located at the base of the neck and is an extremely important gland in the endocrine system. It consists of two side lobes connected by a bridge (isthmus). The thyroid releases hormones that regulate vital functions of the body, such as metabolism, temperature, cholesterol levels, menstruation, cell and tissue development, mobility, etc. These hormones are thyroxine (T4), triiodothyrine (T3) and calcitonin (CT). If the function of the thyroid is disturbed, larger (hyperthyroidism) or smaller (hypothyroidism) amounts of these hormones are produced.

The amount of hormones secreted by the thyroid is regulated by the pituitary gland (at the base of the brain) and more specifically by a hormone it releases called the thyroid-stimulating hormone (TSH). Thus, when levels of T3 and T4 are low, the pituitary gland releases more TSH to increase the production of these hormones. When the levels of T3 and T4 are high, the pituitary gland releases less TSH to slow down production.

Thyroid Disorders: Hypothyroidism

Hypothyroidism is the pathological condition in which decreased secretion of thyroid hormones is observed, and can be either congenital or acquired. Congenital hypothyroidism is diagnosed in the first few days of a child’s life, while the acquired form manifests itself in childhood or adolescence. Many children inherit the disorder from their parents.

Congenital Hypothyroidism (CHT)

It occurs when the thyroid gland does not develop normally or is underactive before the child’s birth. The incidence of the disease ranges from 1:2500 to 1:3000 newborns. Congenital hypothyroidism is due to:

  • Thyroid gland aplasia or hypoplasia. In the case of hypoplasia, the thyroid appears in a different position (ectopic).
  • In hormone synthesis disorders.

The family history, clinical examination, degree of hypothyroidism, and the body’s response to treatment in the first years of the child’s life will determine whether the cause of the disorder is hereditary and whether the treatment will last for life.

Acquired Hypothyroidism

It is caused by an autoimmune disorder called Hashimoto’s thyroiditis, where the child’s immune system attacks the thyroid gland and it does not produce enough hormones for the needs of the body. It usually occurs in girls during puberty. Patients with insulin-dependent diabetes mellitus are at greater risk of developing the condition.

Thyroid Disorders: What are the symptoms of hypothyroidism?

Most newborns with congenital hypothyroidism have no symptoms. A very small percentage (5%) may exhibit some early signs, including:

  • Prolongation of pregnancy
  • Increased weight of the newborn
  • Jaundice
  • Hypothermia
  • Sluggishness and fatigue
  • Hoarse cry
  • Large tongue protruding from the mouth
  • Swelling of the face and genitalia.

Some of the symptoms presented by children with acquired hypothyroidism are:

  • Low stature
  • Slow thought process
  • Stunted tooth and bone growth
  • Fatigue
  • Slow speech
  • Dry skin
  • Fragile hair
  • Constipation
  • Late puberty.

Thyroid Disorders: Hyperthyroidism

Hyperthyroidism results from an increase in thyroid hormone levels in the blood and usually occurs in teenage girls. The main cause of hyperthyroidism is Graves’ Disease, an autoimmune condition in which antibodies are produced that affect the function of the thyroid, forcing it to secrete a large amount of thyroid hormone. There is usually a genetic predisposition for the disease. Another cause is toxic nodular goitre, which is due to the development of one or more nodules that result in the excessive secretion of thyroid hormones.

Thyroid Disorders: What are the symptoms of hyperthyroidism?

Children with hyperthyroidism have:

  • Increased appetite and weight loss
  • Fast or irregular heartbeat (tachycardia)
  • Nervousness
  • Irritability
  • Trembling hands
  • Fatigue
  • Swollen goitre
  • Menstrual disorders
  • Insomnia

Thyroid Disorders: How are they diagnosed?

The doctor will take a detailed family history and conduct a clinical examination. The diagnosis will be based on the results of the following tests:

  • T3, T4 and TSH levels
  • Thyroglobulin (TGAb) and thyroid peroxidase (TPO) antibodies
  • Thyroid ultrasound to determine the position and morphology of the gland and the presence or absence of nodules.

Thyroid Disorders: Nodules

An ultrasound of the thyroid may reveal one or more nodules. This test enables the endocrinologist to check the size and composition of the nodules. In most cases, a fine needle aspiration biopsy (FNA) will not be required, unless the nodule is solitary or larger than 1 cm. Symptoms do not usually appear or affect the function of the thyroid.

Thyroid Disorders: How are they treated?

Hypothyroidism treatment lasts for life and includes oral hormone replacement therapy with levothyroxine, which is chemically similar to thyroxine T4. The child develops normally through the systematic administration of medication. Dosage is regulated according to the age and weight of the child. Some children with transient thyroid disorder will stop treatment after the first three years when hormone levels return to normal.

In the case of hyperthyroidism, anti-thyroid drugs are administered, inhibiting the overproduction of thyroid hormones. In the event that thyroid function is not successfully regulated, then radioactive iodine is administered. In very rare cases involving the co-existence of nodules, it is recommended that the thyroid be removed surgically.