From the Guidelines
Congenital hypothyroidism is a condition where a baby's thyroid gland doesn't produce enough thyroid hormones, requiring prompt treatment with synthetic thyroid hormone to prevent serious complications. This condition occurs in about 1 in 2,000-4,000 newborns and is most commonly caused by abnormal thyroid gland development or defects in thyroid hormone production 1.
Key Points
- The standard treatment involves daily oral levothyroxine, with the dose adjusted based on blood tests monitoring thyroid function.
- Treatment must begin within the first two weeks of life to prevent permanent intellectual disability and growth problems.
- Most babies show no obvious symptoms at birth, which is why newborn screening programs that test for this condition are crucial.
- Without this screening, symptoms might develop gradually and include jaundice, poor feeding, constipation, sleepiness, low muscle tone, large tongue, umbilical hernia, and delayed growth.
- Treatment is lifelong for most affected individuals, with regular monitoring of thyroid hormone levels especially during periods of rapid growth. It's essential to note that while the provided study 1 discusses thyroid disease in pregnancy, it highlights the importance of monitoring and treating thyroid conditions in pregnant women to prevent complications such as congenital hypothyroidism.
Prevention and Screening
- Newborn screening programs are vital in detecting congenital hypothyroidism early, allowing for prompt treatment and preventing long-term complications.
- Pregnant women with thyroid conditions, such as Graves' disease or hypothyroidism, should be closely monitored and treated to minimize the risk of congenital hypothyroidism in their babies 1.
From the Research
Definition and Prevalence of Congenital Hypothyroidism
- Congenital hypothyroidism (CH) is defined as thyroid hormone deficiency present at birth 2, 3, 4, 5.
- It occurs in approximately 1:2,000 to 1:4,000 newborns 2 or 1:2000-4000 newborns 4.
- CH is a disorder of thyroid hormone deficiency which develops secondary to incomplete thyroid development or inadequate thyroid hormone production 5.
Clinical Manifestations and Diagnosis
- The clinical manifestations of CH are often subtle or not present at birth, likely due to trans-placental passage of some maternal thyroid hormone and some residual neonatal thyroid function 2, 3.
- Common symptoms include decreased activity and increased sleep, feeding difficulty, constipation, and prolonged jaundice 2, 4.
- Common signs include myxedematous facies, large fontanels, macroglossia, a distended abdomen with umbilical hernia, and hypotonia 2, 4.
- Diagnosis is confirmed by finding an elevated serum TSH and low T4 or free T4 level 2.
- Other diagnostic tests, such as thyroid radionuclide uptake and scan, thyroid sonography, or serum thyroglobulin determination, may help pinpoint the underlying etiology 2.
Classification and Treatment
- CH is classified into permanent and transient forms, which can be divided into primary, secondary, or peripheral etiologies 2, 3.
- Permanent CH refers to a persistent deficiency of thyroid hormone that requires life-long treatment 3.
- Transient CH refers to a temporary deficiency of thyroid hormone that is discovered at birth but recovers to normal in the first few months or years of life 3.
- Levothyroxine is the treatment of choice, with a recommended starting dose of 10 to 15 mcg/kg/day 2.
- The immediate goals of treatment are to rapidly raise the serum T4 above 130 nmol/L (10 ug/dL) and normalize serum TSH levels 2.
Prognosis and Outcome
- The prognosis of infants detected by screening and started on treatment early is excellent, with IQs similar to sibling or classmate controls 2.
- Delayed or omitted treatment can lead to devastating neurocognitive outcomes, making CH the leading cause of preventable intellectual disability in children 5.
- Frequent laboratory monitoring in infancy is essential to ensure optimal neurocognitive outcome 2.