Congenital Hypothyroidism: A Detailed Overview

Congenital hypothyroidism, formerly known as cretinism, is a deficiency of thyroid hormone in newborn babies. The disease might be caused by a malfunction with the baby's thyroid gland or a shortage of iodine in the mother's body when pregnant. 

Thyroid hormone is vital for a baby’s growth and brain development. Therefore, untreated congenital hypothyroidism may lead to cognitive impairments and stunned growth. However, with prompt diagnosis and treatment, the baby can likely lead a normal and healthy life.

This article delves into the causes, symptoms and treatment of congenital hypothyroidism. It provides insights into their signs, diagnosis, treatment and long-term effects.

What are the Causes of Congenital Hypothyroidism?

Congenital hypothyroidism may result from multiple factors which are as follows:

• An abnormally small or poorly formed thyroid gland
• Genetic abnormalities that disrupt thyroid hormone production
• Insufficient iodine in the mother's diet during pregnancy
• Uses of medicines that destroy thyroid hormone production (sulfonamides, antithyroid drugs, or lithium during pregnancy)

What are the Symptoms of Congenital Hypothyroidism?

Symptoms of congenital hypothyroidism are as follows:

• Dry or pale skin
• Abdominal swelling around the navel
• Jaundice, or yellowing of the skin and eyes
• Lack of weight gain
• Excessive sleep
• Fatigue
• Hoarse voice
• Thickened or unusual facial features
• Irregular bone development
• Poor feeding
• Very little crying
• Cognitive impairment
• Constipation
• Neck swelling due to an enlarged thyroid gland (goitre)

How is Congenital Hypothyroidism Diagnosed?

Diagnosing congenital hypothyroidism is done by screening for this disease using blood drawn from the baby's heel before discharge. This method is known as newborn screening. 

When the screening software detects a positive result (a low amount of thyroid hormone combined with a high level of thyroid-stimulating hormone, or TSH, from the pituitary), it indicates potential thyroid dysfunction.

Before beginning medication, the baby's doctor will need a blood sample from a vein to confirm the diagnosis of congenital hypothyroidism. In rare circumstances, the doctor may perform a thyroid scan to determine whether the thyroid gland is absent or too tiny.

What is the Treatment for Congenital Hypothyroidism?

In the treatment for congenital hypothyroidism, the lost thyroid hormone is replaced to restore normal thyroid hormone levels. The most prevalent thyroid hormone medicine, levothyroxine, is available only as a tablet. It can be provided in crushed form combined with a tiny amount of water, or breastmilk.

Providing thyroid hormone replacement every day and scheduling regular appointments with a doctor can help guarantee that the thyroid grows and develops normally. The doctor will do frequent thyroid function tests to ensure that the child's medication dose is adjusted appropriately as he or she develops.

Long-term Effects and Management in Congenital Hypothyroidism

Newborn screening for congenital hypothyroidism is one of medicine's greatest successes in early detection, though challenges remain in addressing developmental and neurological outcomes in some cases.

Despite early identification, all outcome studies reveal that up to 10% of individuals continue to have issues with mental development and neurological symptoms. An inadequate dosage of thyroid hormone substitution and compliance issues are all clearly associated with a worse outcome.

Recent research has found that chronic mental retardation and neurological symptoms in certain individuals are caused by abnormalities in factors expressed in both the thyroid gland and the central nervous system (CNS) during embryonic development.

Understanding these molecular abnormalities is essential because they can disrupt the development of both the thyroid gland and the brain, which results in poor outcomes in congenital hypothyroidism.

Therefore, by finding these molecular faults, doctors hope to improve diagnosis accuracy, which allows for more effective counselling and treatment for affected kids discovered through newborn screening programs.

Potential Outcomes Of Congenital Hypothyroidism

The outcomes for congenital hypothyroidism can be found. Early and proper therapy beginning before the second week of birth will result in appropriate global intelligence. However, uncertain or subtle deficiencies in verbal abilities, attention, memory, or motor development may be present, especially in individuals with severe congenital hypothyroidism. 

The severity of congenital hypothyroidism and pretreatment thyroxine (T4) levels are critical predictors of cognitive and motor development outcomes. Studies suggest that infants with thyroid agenesis tend to have lower intelligence quotient scores compared to those with thyroid dysgenesis.

This discrepancy may be attributed to brain damage occurring in the early pregnancy period due to insufficient thyroid hormone levels.

In cases of severe congenital hypothyroidism, initiating treatment with high doses of levothyroxine (L-T4) at 10–15 micrograms per kilogram (mcg/kg) effectively and rapidly normalises serum thyroid-stimulating hormone (TSH) levels. 

This treatment approach has been shown to support the development of normal global IQ scores by 4 years of age, ensuring early and full recovery of the brain.

Prevention and Awareness

Conclusion 

Congenital hypothyroidism is a serious but treatable condition that emphasises the importance of early detection and intervention. Infants diagnosed with congenital hypothyroidism can achieve normal growth and neurodevelopment when they receive timely and appropriate levothyroxine therapy, along with regular monitoring by the doctor.