Nothing can match the worry of parents for their children. Indeed, it is very disturbing to see a distressed mother holding her sick baby in her hands. To escape such situation we have to be extra cautious about thyroid hormones.
Your child’s thyroid is a small butterfly shaped organ located at the base of the neck. It produces thyroid hormones that are responsible for metabolism, growth and mental development.
Cretinism is extreme hypothyroidism (underproduction of thyroid hormones) during fetal life, infancy or childhood. Underactive thyroid is a concern for middle aged women. It poses an even greater threat for children, as it adversely affects the growth and mental capabilities of the children, interfering with the normal development and growth.
Congenital hypothyroidism, aka congenital cretinism, is the underactive thyroid gland at the time of birth. In United States the incidence of congenital hypothyroidism has increased 138% over last two decades (Mol Genet Metab. 2007; 91(3):268-277). It can result from either anatomical defects or functional compromise of the thyroid before birth.
- Congenital lack of thyroid gland (thyroid dysgenesis).
- Improper development of thyroid gland.
- Failure of thyroid gland to produce thyroid hormone because of a genetic defect of the gland.
- Underproduction of thyroid hormones due to lack of iodine in the diet.
The symptoms of congenital hypothyroidism are usually not evident at birth. It’s because the fetus was supplied by maternal thyroid hormones in uterus. However, a few weeks later, the neonate’s movements start to become sluggish. The neonate is referred as “good baby” because of less crying and decreased movements. They sleep most of the time. Later, both physical and mental growth impairments are evident. The additional symptoms of congenital hypothyroidism are decreased muscle tone, poor feeding and weight gain, constipation, hoarse cry, puffy face, and larger anterior fontanelle.
Acquired hypothyroidism is different from congenital hypothyroidism as it develops after birth in newborns. The two most prevalent causes of acquired hypothyroidism are autoimmune hypothyroidism and central hypothyroidism.
In autoimmune hypothyroidism (Hashimoto’s thyroiditis), the immune system starts attacking its own body cells. The normal thyroid is tagged for destruction, which results in under production of thyroid hormones.
While in central hypothyroidism, the pituitary gland doesn’t secrete normal amounts of thyroid stimulating hormone (TSH). TSH normally functions to stimulate the thyroid gland to produce thyroid hormones. Low levels of TSH results in under activation of the thyroid, although the thyroid is normal.
- Iatrogenic Hypothyroidism:
Iatrogenic hypothyroidism is the term used when hypothyroidism is induced by the physician’s treatment or medications. It may result from thyroid ablation (destruction) or a surgically removed thyroid. It is also a form of acquired hypothyroidism.
At the time of birth, some individuals show temporary symptoms of hypothyroidism, known as transient hypothyroidism. Later, it is reverted back and usually it does not require a long term treatment. It is identified in the neonatal screening and is causing increased survival rate in premature births.
The causes of transient hypothyroidism includes maternal anti thyroid antibodies, iodine deficiency in the womb, prenatal or postnatal iodine excess, mutations and also maternal anti thyroid medication.
Symptoms of Hypothyroidism in Children:
Most of the symptoms of hypothyroidism in children are the same as adults. The same symptoms are as follows:
- Increased weight
- Tiredness or fatigue
- Cold intolerance
- Poor appetite
The different symptoms are as follows:
- Large anterior fontanelle
- Slow growth
- Mental impairments
- Delayed tooth development
- Hoarse cry
- Choking episodes
- Poor muscle tone
- Delayed puberty
Diagnosis of Neonatal Hypothyroidism:
Congenital hypothyroidism is identified in routine neonatal screening. In older children, blood tests are done by the primary physician or endocrinologist.
- Physical examination:
It is an immediate tool to help diagnose hypothyroidism. Any swelling in neck area is noted. It is known as a goiter. The swelling is due to thyroid enlargement. Newborns can experience diminished muscle tone, swelling in face and eyes and jaundice (yellowing of skin).
- Blood tests:
Common blood tests measure the T4 and TSH hormone levels in blood. Usually low T4 levels and high TSH levels confirm the diagnosis. However, sometimes low TSH levels also give the positive findings. Normal hormone ranges in children differ from the adult hormone ranges. So, it is best to consult a pediatric endocrinologist.
Additional imaging scans can be done to find out the cause of disease. These scans are not necessary for the diagnosis but, provide additional information about the disease etiology. A missing or small thyroid is easily shown on the scans.
Early diagnosis and prompt treatment by a medical doctor is crucial for the good prognosis of disease. Thyroid hormone replacement is the most common treatment. It is done to normalize hormone levels.
Levothyroxine is widely used and is recommended for treatment (J Pediatr Endocrinol Metab. 2007 May. 20(5):559-78.). Follow up with your doctor is really important. Children with hypothyroidism should be clinically monitored throughout the treatment.
How Can You Prevent It?
- The risk factors associated with cretinism needs to be eliminated or at least reduced to prevent the disease. Get your checkup before conceiving to rule out any risk factor associated with the disease.
- The largest risk factor is maternal age greater than 40 and already having hypothyroidism. If you have Hashimoto’s thyroiditis or any other autoimmune disease, your child is more likely to suffer from congenital cretinism.
- Iodine deficiency is the most common cause of congenital hypothyroidism around the world. It is the leading cause of preventable brain damage (Chen, Zu-Pei; Hetzel, BS, Feb, 2010) Therefore, it should be addressed to reduce the chances of disease.
- Neonatal screening and early diagnosis by your primary medical doctor or endocrinologist can help in prompt treatment. It should be encouraged as early invention is associated with good prognosis.
Hypothyroidism mainly affects middle aged and older women, but even children are not safe from it. Cretinism (hypothyroidism in children) has adverse consequences of mental abnormalities and growth impairment.
Risk factors associated with the disease can be reduced through early screening for the newborn. Premature birth mortality rate is largely reduced over the past few decades as a result of early screening.