The tale of the thyroid gland…

In my last blog post, you met Abha who narrated how her son Abhik was diagnosed with congenital hypothyroidism through the newborn screen, to her sister Avni.

If you haven’t read the previous post, do visit it at http://drsapnanayak.com/2020/04/a-prick-that-every-newborn-deserves/ to learn how you can protect your child’s brain by timely detection of congenital hypothyroidism through the newborn screen.

Having listened to Abha, Avni is now impatient to learn more about Abhik’s journey from the detection of congenital hypothyroidism till the present day.

As they finish lunch, Avni catches hold of her sister and puts forth her queries. 

I am sure you are as curious as Avni. 

Here I take you through their conversation that throws light on congenital hypothyroidism.

Avni asks “Nobody in our family ever had a thyroid illness. How did Abhik get affected? What is congenital hypothyroidism due to?

Abha speaks, “Congenital hypothyroidism is a condition of inadequate secretion of thyroid hormones T4(thyroxine) and T3 (triiodothyronine) from the thyroid gland. 

It may be due to 

– An intrinsic defect in the thyroid gland (primary hypothyroidism) or 

– Deficient TSH (thyroid-stimulating hormone) secretion from the pituitary gland (central hypothyroidism).

 Congenital refers to the defect being present since birth.

 Nevertheless, depending on the severity of the deficiency, the manifestation may occur in the newborn period or later in childhood. 

How the flaws arise in these glands is not known. It is implicated that genetic abnormalities may give rise to these anomalies. But in the majority of cases, the disease is not inherited from the parents.”

Avni’s next question pops up, “Abhik’s deficiency was evident through the result of the newborn screen.

How is congenital hypothyroidism identified, in the unfortunate case where a baby is not tested?”

Abha has got the answer, “The affected baby is born with normal weight and length, and looks healthy. If the baby is not tested by the newborn screen and has a profound deficiency, the features appear in the first few days of life. 

The baby may have the following features, which are, however, not specific 

  • Delayed passage of meconium (the first stools beyond 48 hours) 
  • Poor feeding, protruding tongue
  • Decreased movements of limbs
  • Prolonged jaundice in the newborn period
  • Umbilical hernia (swelling at the navel)
  • Cold and dry skin
  • Puffiness around the eyes, hoarse cry

The appearance of these features should alarm the need to see the doctor urgently. 

The manifestations are a signal to the ongoing brain damage. There lies the importance of newborn screening, through which the condition can be diagnosed before the damage is caused, in the early asymptomatic period.

In a small number of cases, where there is mild deficiency and the body compensates, there may not be severe brain damage. The child may manifest at a later age with goiter (thyroid swelling in the neck) or poor height gain or poor school performance.”

Okay. I now understand how important it is to be aware of this condition and newborn screening. I will make sure my baby is tested for congenital hypothyroidism after 48-72 hours of birth. But, Abha tell me, why are the hormones not being synthesized adequately?” 

Avni is puzzled,

“What are the causes of congenital hypothyroidism?

Well-learned Abha explains, “The reason can be anything of the few.

The thyroid scan and ultrasonography are done to identify the cause, once the diagnosis is confirmed.

  1. Thyroid dysgenesis: 

About 80 to 85% of cases are due to developmental defects in the structure of the thyroid gland. 

 The thyroid gland may not develop at all (agenesis) or maybe small (hypoplastic) or mispositioned and small (ectopic thyroid gland).

2. Dyshormonogenesis

In another 15% cases, the gland is normally formed but, the defect is in the process of synthesis of thyroid hormones. 

The thyroid hormone synthesis is a process where multiple chemical reactions culminate into the formation of T3 and T4 and any step can be faulty.

3. Iodine deficiency: Iodine is an essential element that forms a part of T3 and T4.

Iodine deficiency in the hilly areas with soil deficient in iodine and non-consumption of iodized salt by pregnant women lead to permanent brain injury in the baby, a condition called endemic cretinism.

Apart from these, there are rare causes that lead to transient hypothyroidism in the baby, that resolve after few months, like maternal antithyroid medications or antibodies from the mother that cross the placenta and block the baby’s hormone synthesis.”

Avni is pleased to learn the many facts from her sister. Her intensely inquisitive brain is ready with the next set of questions, 

“How is congenital hypothyroidism treated? When should the treatment be started?”

“Congenital hypothyroidism is treated with Levothyroxine tablets.

The L-thyroxine is the synthetic T4 that replaces the body’s deficient T4. The T4 gets converted to the T3 in the body. 

The medicine is available as tablets of different strengths. Currently, no liquid formulation is commercially available in India. The doctor decides the dose that the child needs to consume, based on the child’s age, weight, and thyroid function status.  

The treatment must be started immediately on the confirmation of the diagnosis. The entire process is therefore hastened to ensure the treatment is begun within the first 2 weeks of life to prevent the irreversible brain damage.”

How is the levothyroxine tablet consumed?

Abha goes on, “The L-thyroxine is prescribed as once-daily dosage, taken at a fixed time of the day, empty stomach, preferably every morning. 

You should remember it as the first thing to do after the child wakes up and brushes his/her teeth in the morning. 

Precaution must be taken not to consume it with other foods or medicines containing iron, calcium, which hamper its absorption.” 

“I am glad that Abhik was timely diagnosed and treated promptly. But how did you give these tablets to him while he was a baby?” asks Avni. 

“The thyroxine is available only as tablets. I gave him the tablets as per the doctor’s instructions.

–        The tablet should be crushed into powder and mixed with few drops of expressed breast milk/water. Try not to feed the baby for the next half hour so that the child does not vomit the tablet out with the feed. 

I religiously followed what the doctor taught me”, said Abha gleefully.

“Do you ever forget giving the dose?” Avni wondered.

“No. Never do I forget his dose.

 Initially, I used to set a reminder on my phone. 

The doctor then introduced the pillbox to me. With this, in the rare instance that I missed giving him a dose, I realized it looking into the pillbox, and gave him the dose the next day. 

Moreover, Abhik’s dad and I share the responsibility and take turns every month to feed Abhik his dose. So, it has never been a burden on me.

Nowadays, Abhik himself comes over and reminds us when it’s time for his pills”, Abha proudly claimed. 

Avni laughed as she spoke, “Yeah, I saw the little boy asking for his medicines this morning. He is certainly a brilliant chap.

How often does he have to see the doctor? Do you have to repeat his tests often?” 

“Yes. Once the baby is started on replacement with the hormones, the adequacy of the treatment needs to be monitored. 

This is necessary, as, in the early life the baby is rapidly growing and its weight increases. Moreover, this is a crucial time when the brain develops. 

So, if the hormones are not reaching adequate levels, there can be impairment in the brain development. 

The monitoring is done through blood tests for TSH or T4 or both.

Initially for one year, the doctor needs to be seen every 2 monthly. After that, with regular treatment, compliance and normal reports, the doctor asks for a 3-monthly visit till 3 years of age and thereafter every 3-6 monthly till adulthood.

But, if you do not ensure the treatment is taken daily, as instructed, the doctor may call for more frequent visits.

At every visit, the doctor also monitors that the child is growing and developing normally,” Abha explained.

Avni exclaimed, “Congratulations dear, that’s a heroic task you are doing! I am proud of you, sister. I appreciate the vast knowledge you have gathered on congenital hypothyroidism while taking care of your child. 

But, how long does the child have to take this treatment?”

“That depends upon the cause of hypothyroidism. In the case of the permanent causes like a structural thyroid defect or a fault in the hormone synthesis, lifelong treatment is needed. 

But rarely, the cause may be transient, as in the case of maternal anti-thyroid medications or maternal blocking antibodies.

In such a case, the pediatric endocrinologist decides if it is necessary to re-evaluate the child in order to stop the treatment, which is done only after 3 years of age. 

IN NO CASE SHOULD THE CHILD’S TREATMENT BE DISCONTINUED ON YOUR OWN WITHOUT THE ADVICE FROM THE EXPERT,” Abha concludes. 

Avni is content with the new information and left with no more questions.

In case you are, do not hesitate to send across your queries. 

Thank you for reading through the post. Do not forget to share the knowledge.

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