Paediatric Endocrinology: Diseases of The Thyroid Gland in Children
1. Mohd Ahmad
2. Osmonova Gulnaz Zhenishbaevna
(1. Student, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic
2. Teacher, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic)
Abstract
Disorders of the thyroid gland are an important group of endocrine disorders in children and adolescents. Thyroid hormones are vital in controlling aspects such as metabolism, physical growth, neurological development, bone development and puberty. If there are any abnormalities in thyroid function during childhood, this can cause serious problems. The main disorders of the thyroid gland include congenital hypothyroidism, acquired hypothyroidism, hyperthyroidism, autoimmune thyroiditis, goitre and thyroid nodules. Congenital hypothyroidism is particularly important as it can cause lasting neurological damage if not diagnosed and treated timely. A major cause of acquired hypothyroidism is Hashimoto's thyroiditis. Graves' disease is the most common cause of hyperthyroidism in paediatric patients. This review looks at the main thyroid disorders in children, the causes, presentations, investigations and treatments. Timely diagnosis, appropriate investigations and tailored treatment will ensure normal growth and development.
Keywords: Paediatric endocrinology; Thyroid disorders; Congenital hypothyroidism; Hashimoto's thyroiditis; Graves' disease; Thyroid function.
Introduction
The thyroid gland is an important endocrine organ found in the anterior part of the neck. It contains two thyroid lobes which are connected by the isthmus. The thyroid secretes thyroxine (T4) and triiodothyronine (T3) which helps control many processes in the body including metabolism, body temperature, cardiovascular function, protein synthesis and bone growth. Calcitonin is also produced. The production of thyroid hormones is controlled by the hypothalamic-pituitary-thyroid axis. Thyrotropin releasing hormone is secreted from the hypothalamus which stimulates thyroid stimulating hormone (TSH) to be released from the anterior pituitary. Thyroid hormones are vital in normal brain development in children, especially during foetal development. They can also affect height, bone development, puberty and cognition. Too little or too much thyroid hormone can have a negative impact on the development of children. Thyroid disorders can be congenital or acquired and can have varied presentations depending on the age of the child, how long they have had the illness for and how much of a hormonal imbalance they have. Congenital hypothyroidism, autoimmune thyroiditis, Graves’ disease and goitre are just some of the most clinically significant disorders. Early diagnosis and appropriate management can help prevent long term complications.
Methods
A narrative review was completed looking at thyroid disorders in children. Scientific articles, guidelines, paediatric endocrinology textbooks and publications relating to thyroid physiology, epidemiology, presentation, investigations and treatment were considered.
The review looked at congenital and acquired thyroid disorders, hyperthyroidism, autoimmune thyroiditis, goitre and thyroid nodules. Investigations such as thyroid function tests (TSH, free thyroxine), thyroid autoantibodies and ultrasound were considered. Treatments and the importance of early diagnosis were looked at. Information was collated and organised into the main groups of thyroid disorders in children.
Results
Congenital Hypothyroidism
Congenital hypothyroidism occurs when there is a lack of thyroid hormone at birth. This can be caused by a malformation of the thyroid gland, ectopic thyroid tissue, impaired production of thyroid hormones or issues with iodine availability. Sometimes medications or thyroid issues in the mother can cause temporary thyroid dysfunction in the neonate.
Clinical presentations can include prolonged jaundice, poor feeding, constipation, lethargy, macroglossia, hypotonia, umbilical hernia and dry skin. However, many neonates will not present with any obvious symptoms and would require neonatal screening.
The main diagnosis is made using neonatal screening. TSH and FT4 levels should be measured to confirm. Primary congenital hypothyroidism will typically show high TSH levels and low FT4. Levothyroxine is the treatment of choice. Treatment should be started as soon as possible, ideally within the first 2 weeks of life. Regular monitoring of thyroid function and neurological development is required.
Acquired Hypothyroidism
Acquired hypothyroidism occurs when there is a lack of thyroid hormone production after birth. Hashimoto’s thyroiditis is the most common cause in iodine sufficient areas. This is an autoimmune disease-causing destruction of the thyroid gland. Other causes can include iodine deficiency, thyroid surgery, radiation exposure, certain medications and hypothalamic/pituitary disorders.
Symptoms can include fatigue, weight gain, cold intolerance, constipation, dry skin, hair loss and reduced activity. Children can present with reduced linear growth, delayed bone age and delayed puberty. Goitre can also be seen. TSH and FT4 levels should be measured. Primary overt hypothyroidism typically presents with elevated TSH and reduced FT4. Anti-thyroid peroxidase and anti-thyroglobulin antibodies can help confirm the diagnosis of autoimmune thyroiditis. Levothyroxine is used as a replacement. This is tailored to the specific child depending on their age, weight, blood results and severity. Regular monitoring of growth, development and thyroid function is important.
Hyperthyroidism
Hyperthyroidism occurs when there is excessive production of thyroid hormones. The most common cause in children and adolescents is Grave’s disease. This is an autoimmune disorder where antibodies stimulate the thyroid gland via thyroid stimulating receptors. Children can present with weight loss, increased appetite, tachycardia, increased sweating, intolerance to heat, shaking hands, irritability, anxiety, sleep disturbance and increased bowel movements. Grave’s disease can also present with goitre and eye signs such as proptosis.
Laboratory investigations will typically show reduced TSH and increased FT4/T3. TSH receptor antibodies can help confirm Grave’s disease. An ultrasound can be performed. Methimazole is typically the drug of choice in children. Occasionally beta blockers can be prescribed to help with the cardiovascular symptoms. Radioactive iodine or thyroidectomy can be considered in select cases if the disease does not respond well or they are having significant side effects.
Autoimmune Thyroiditis
Autoimmune thyroiditis, such as Hashimoto’s thyroiditis, is a common thyroid disorder in children and adolescents. It occurs when the immune system produces antibodies to attack parts of the thyroid, leading to chronic inflammation. Sometimes this can be asymptomatic and picked up on by an enlarged thyroid or abnormal lab results. Some children can suffer from fatigue, constipation, weight gain, dry skin and growth issues as their thyroid function becomes hypothyroid.
This can be diagnosed by performing thyroid function tests and looking for thyroid autoantibodies. Anti-TPO antibodies are particularly useful. An ultrasound can show an uneven thyroid. Treatment depends on the thyroid function. Children with overt hypothyroidism will need levothyroxine. Those with normal thyroid hormone levels may need to be regularly reviewed.
Goitre
Goitre occurs when the thyroid enlarges. Important causes in children include iodine deficiency, autoimmune thyroiditis, Grave’s disease and inherited thyroid hormone production issues. The most obvious symptom is an enlarged thyroid in the anterior neck. Large goitres can cause difficulty swallowing. A clinical examination should be performed looking at the thyroid. TSH and FT4 levels should be measured. Thyroid antibodies should be checked. An ultrasound can be performed if required. The cause of the goitre should be treated. Ensuring adequate iodine intake is important if there is iodine deficiency.
Thyroid Nodules/Malignancy
Thyroid nodules are less common in children but need to be carefully assessed as there is a higher rate of malignancy. Symptoms can include a palpable thyroid lump, painless swollen neck or enlarged lymph nodes in the neck. Some people will have no symptoms and it can be picked up on examination or investigations. An ultrasound is the main investigation to look at the size of the nodule and whether it has suspicious features. TSH levels should be measured. A fine needle biopsy can be performed if clinically indicated. The most common thyroid malignancy in children is differentiated thyroid cancer (particularly papillary thyroid cancer). This is typically treated with surgery. Radioactive iodine can also be considered in selective cases.
Investigations for Thyroid Disorders in Children
To make an accurate diagnosis investigation should be performed.
Important investigations include:
● TSH – To assess thyroid function and pituitary stimulation.
● Free T4 – To assess available thyroxine.
● T3 – Useful if hyperthyroidism is suspected.
● Anti-TPO – Can help make the diagnosis of autoimmune thyroiditis.
● TSH receptor antibodies – Can help identify Grave’s disease.
● Thyroid ultrasound – To look at thyroid size, structure and nodules.
Fine needle biopsy – Can help assess suspicious thyroid nodules.
When interpreting thyroid function tests, it is important to know the child’s reference ranges for their age and their clinical situation.
Complications of Thyroid Disorders
If thyroid disorders are left untreated there can be significant complications in children. Congenital hypothyroidism can cause lasting neurological damage if not treated timely. Acquired hypothyroidism can cause reduced height velocity, delayed bone development and delayed puberty. Hyperthyroidism can cause poor weight gain, cardiovascular problems, muscle weakness and reduced bone mineral density. Severe untreated thyrotoxicosis can occasionally progress to thyroid storm which is a life-threatening endocrine emergency. These complications highlight the importance of early diagnosis and appropriate treatment.
Discussion
Thyroid disorders are an important aspect of paediatric endocrinology as thyroid hormones affect almost all aspects of growth and development in children. Unlike many endocrine disorders in adults, thyroid dysfunction in children can cause long term effects on neurological development, bone development, growth and reproduction.
Congenital hypothyroidism is important from a public health standpoint. Neonatal screening programmes have enabled early identification of children with hypothyroidism. Treatment with levothyroxine can significantly reduce the risk of developmental issues. Hashimoto’s thyroiditis is a major cause of hypothyroidism in iodine sufficient populations. It can present with subtle symptoms and some children can be asymptomatic for a long period of time. Clinical suspicion and appropriate biochemical investigations are important to make a diagnosis. This is especially important in children presenting with unexplained growth issues or thyroid enlargement. Grave’s disease is the main cause of hyperthyroidism in children. Presentation can be different to adults with behavioural changes, difficulties with school, sleep issues and reduced concentration sometimes being the first signs. Most children can be treated with Methimazole initially. However, some may require long term treatment and specialist follow up. Iodine intake is important. Too little or too much can cause issues with thyroid hormone production. Iodised salt and educating people about their diet can help prevent this at a population level.
Thyroid nodules are not common in children but need to be carefully assessed as there is a higher proportion of malignancy. Risk stratification using ultrasound and appropriate biopsy can help. Despite advances in investigations and treatment there can be problems with delayed diagnosis, lack of access to neonatal screening, inconsistent follow up and poor medication compliance. Increasing awareness amongst parents can help overcome these issues. Thyroid disorders in children should be treated in a tailored manner depending on the child’s age, diagnosis, blood results and their development. Working with paediatricians, endocrinologists, lab specialists and families will ensure the best outcomes.
Conclusion
Thyroid gland disorders are significant in paediatric endocrinology as they affect metabolism, neurological development, growth and puberty. The main disorders seen in children are congenital hypothyroidism, acquired hypothyroidism, Grave’s disease, autoimmune thyroiditis, goitre and thyroid nodules. Neonatal screening, careful clinical examination, thyroid function tests and appropriate imaging are important for early diagnosis. Levothyroxine, anti-thyroid medications and selected surgery can be used as effective treatments. Early diagnosis, adequate iodine intake, regular monitoring and educating parents can help prevent complications and improve the long-term health and quality of life in children with thyroid disorders.
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