Acquired hypothyroidism is a post-birth condition where your body produces insufficient levels of thyroid hormone.

Hypothyroidism is a relatively common condition that can affect both adults and children. It occurs when your thyroid gland doesn’t produce enough hormones. This has various effects on your body’s metabolism and nervous system.

When hypothyroidism develops later in childhood and is not present at birth, it’s typically known as “acquired hypothyroidism.” This condition can cause problems like slow growth, fatigue, and delayed puberty.

Acquired hypothyroidism, when diagnosed in children, is sometimes referred to as juvenile hypothyroidism. It occurs when the thyroid doesn’t produce enough hormones, leading to metabolic and neurological effects.

In children, the condition typically emerges between ages 9 and 11 years, with symptoms such as poor growth, constipation, lethargy, and dry skin.

Hypothyroidism occurs in about 1 in 1,250 children.

Why call it “acquired” hypothyroidism?

Acquired hypothyroidism refers to a type of hypothyroidism that is not congenital, meaning the condition developed after birth and is distinct from cases present at birth.

The term “acquired hypothyroidism” generally refers to children and adolescents to distinguish between children who developed hypothyroidism at birth.

Although many adults also have acquired hypothyroidism, it is generally just referred to as “hypothyroidism.”

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Acquired hypothyroidism symptoms

Symptoms of acquired hypothyroidism may include:

  • Poor growth: Children with acquired juvenile hypothyroidism may experience slowed growth, resulting in shorter height than their peers.
  • Fatigue and lethargy: Low thyroid hormone levels can cause persistent fatigue, lethargy, and a general lack of energy.
  • Weight gain: Children may experience unexplained weight gain due to a slowed metabolic rate.
  • Constipation: Hypothyroidism can affect the digestive system, leading to constipation and difficulty passing stools.
  • Cold sensitivity: Children with hypothyroidism might feel excessively cold, even in mild temperatures.
  • Dry skin: The skin may become dry, rough, and flaky.
  • Changes in hair and nails: Hair may become thin, brittle, and dry, and the nails may become brittle or develop ridges.
  • Hoarse voice: Hypothyroidism can affect the vocal cords, leading to a hoarse or deepened voice.
  • Delayed puberty: In adolescents, hypothyroidism can delay the onset of puberty, including the development of secondary sexual characteristics.
  • Cognitive impairment: Children may experience difficulties with concentration, memory, and cognitive function.
  • Mood changes: Mood swings, irritability, or depression can occur in individuals with hypothyroidism.
  • Muscle weakness: Muscle weakness and aches might be present due to reduced metabolism and energy production.
  • Bradycardia: The heart rate may slow down (bradycardia).
  • Elevated cholesterol: Hypothyroidism can lead to elevated cholesterol levels.

Approximately 80% of children and adolescents with acquired hypothyroidism are asymptomatic at the time of diagnosis.

Acquired hypothyroidism, especially in the context of juvenile hypothyroidism, is most commonly due to an autoimmune condition called Hashimoto’s thyroiditis (HT).

In HT, the body’s immune system attacks the thyroid gland, leading to inflammation and gradual destruction of the gland’s ability to produce thyroid hormones. This results in reduced levels of these hormones in the body, leading to the symptoms of hypothyroidism.

Other less common causes of acquired hypothyroidism can include certain medications, radiation therapy to the neck, and in rare cases, problems with the pituitary gland or hypothalamus that affect the regulation of thyroid hormone production.

Acquired hypothyroidism risk factors

A major risk factor for acquired hypothyroidism, especially the autoimmune form of Hashimoto’s thyroiditis, is having a family history of autoimmune diseases (e.g., Hashimoto’s, lupus, diabetes).

In a study involving 861 first-degree relatives of 264 people with HT, the risk of developing HT was found to be nine times higher among relatives compared to the general population.

The prevalence of HT was 16.7% among relatives, with higher rates in parents (22.9%), siblings (19.6%), and lower rates in children (9.6%).

Certain children have a higher risk of developing hypothyroidism, particularly those with type 1 diabetes, congenital syndromes like Turner syndrome or Down syndrome, and individuals who’ve undergone cancer treatment involving radiation.

Additionally, being female increases the risk, as autoimmune thyroid disorders are more common in women. Other risk factors may include certain genetic factors, iodine deficiency (rare in the United States), or certain medications.

Acquired hypothyroidism is typically diagnosed through a combination of clinical assessment and laboratory tests. Healthcare professionals — often endocrinologists or pediatricians — evaluate your medical history and symptoms, and perform a physical examination.

Lab tests include measuring thyroid hormones (T3 and T4) and thyroid-stimulating hormone (TSH) levels in the blood. An elevated TSH level and low T3 and T4 levels are characteristic of hypothyroidism.

Additionally, research suggests that the presence of thyroid antibodies, such as anti-thyroperoxidase (TPO) and anti-thyroglobulin (ATG) antibodies, may indicate autoimmune hypothyroidism.

Subclinical hypothyroidism, a milder form of the condition, may be diagnosed when TSH levels are mildly elevated while free T4 levels are within the expected range.

Acquired hypothyroidism is typically treated with medication. The most common and effective treatment is the daily oral administration of a synthetic thyroid hormone called levothyroxine.

This medication helps to replace the deficient thyroid hormones in the body, restoring standard thyroid function.

The dosage of levothyroxine is carefully adjusted based on regular blood tests to ensure thyroid hormone levels remain within the targeted range. Regular monitoring and adjustments of medication are essential to ensure the best treatment and prevent complications.

Acquired hypothyroidism is a relatively common childhood condition, characterized by the underproduction of thyroid hormones. The most common trigger is Hashimoto’s disease, an autoimmune condition.

It’s important to identify and treat acquired hypothyroidism early to avoid any harmful effects on growth, development, and thinking abilities.

If your child has acquired hypothyroidism, closely watching their health, providing thyroid hormone treatment, and regularly seeing a doctor can help them stay healthy and enjoy life to the fullest.