Clinical_Rounds_in_Endocrinology_Volume_II_-_Pediatric_Endocrinology

101

also occur due to increased maternal transfer of T 4 before 32 weeks of preg-

nancy, which results in inhibition of fetal hypothalamo–pituitary–thyroid

(HPT) axis; this suppression of HPT axis may persist up to 6 months.

56. What is the natural history of TRAb - mediated hyperthyroidism in a neonate
    born to mother with Graves ’ disease?
    TRAb-mediated hyperthyroidism commonly resolves spontaneously within
    3–12 weeks. Persistence of thyrotoxicosis beyond 6 months should raise a pos-
    sibility of McCune–Albright syndrome or TSH receptor-activating mutations.


57. What are the manifestations of neonatal hyperthyroidism?

Neonatal hyperthyroidism is characterized by irritability, restlessness, poor

feeding, failure to thrive, increased appetite, weight loss, diarrhea, sweating,

tachycardia, and heart failure. Goiter is commonly present. Eye signs like peri-

orbital edema, lid retraction, and proptosis may be present even if mother does

not have thyroid-associated orbitopathy. Hepatosplenomegaly, lymphadenopa-

thy, and thymic enlargement may also be present in newborns with hyperthy-

roidism. Skeletal manifestations of neonatal hyperthyroidism include

microcephaly, advanced bone age, and craniosynostosis.

58. How to evaluate a neonate born to mother with Graves ’ disease?

Cord blood sample should be obtained for FT 4 and TSH in neonates born to

mother with Graves’ disease. If thyroid function is normal, repeat testing should

be performed after 1–2 weeks, as transplacental passage of antithyroid drugs

may delay the onset of thyrotoxicosis in these newborns. Estimation of TRAb

is helpful in confi rming the etiology of neonatal hyperthyroidism.

59. How to treat neonatal hyperthyroidism?

Neonatal hyperthyroidism should be managed as thyroid storm, because it is

associated with high mortality (30 %) in untreated neonates. Treatment

includes antithyroid drugs (methimazole 0.25–1 mg/Kg/day in two to three

divided doses), propranolol 2 mg/Kg/day, and iodides if required.

Propylthiouracil is contraindicated as neonates are at a higher risk of hepato-

toxicity. Glucocorticoids should be instituted to tide over the crisis.

Antithyroid drugs are required only for short duration, as TRAbs-mediated

neonatal thyrotoxicosis remits by itself within 2–3 months. However, infants

with McCune–Albright syndrome and TSH receptor-activating mutations

require defi nitive therapy later, after euthyroidism is attained with antithyroid

drugs.

3 Thyroid Disorders in Children