Neonatal Hyperthyroidism in an Infant Born of an Euthyroid Mother

Abstract

An infant with neonatal hyperthyroidism was born to an euthyroid mother previously treated for hyperthyroidism with sodium iodide I 131. Measurable levels of long-acting thyroid stimulator (LATS) were found in mother and infant. A review of previous cases of neonatal hyperthyroidism in which LATS determinations have been performed indicates the importance of LATS in the pathogenesis of this condition. Infants born of mothers with hyperthyroidism or with a history of treated hyperthyroidism should be evaluated in the neonatal period for hyperthyroidism, particularly if measurable levels of LATS have been found in the mother's serum late in pregnancy. Early treatment of neonatal thyrotoxicosis with propylthiouracil is recommended for severely affected cases.

Thyroid-stimulating immunoglobulins and thyroid function tests in two siblings with neonatal thyrotoxicosis

“…The presence of neonatal thyrotoxicosis in at least two successive infants born to a previously thyrotoxic mother confirms earlier reports [4,20] that TSI-positive mothers, irrespective of their thyroid function, are at risk of delivering infants with neonatal thyrotoxicosis. Whilst the clinical and biochemical features of infant 1 suggest exposure to an excess of thyroid hormone in utero, the virtual absence of such features in infant 2 indicates that this exposure was only minimal.…”

Neonatal thyrotoxicosis treated with propranolol.

“…It is known that the clinical severity may vary from mild, requiring no treatment, to fulminant with rapid demise. Without treatment, or with iodides alone, mortality has been reported to be 12% (Samuel et al, 1971). There is also a high fetal mortality.…”

“…There is also a high fetal mortality. The standard treatment has been to give carbimazole or thiouracil, with or without thyroxine, to the mother and to treat the neonate with sedatives, iodides, carbimazole, or thiouracil combined with digoxin if required (Adams, Lord, and Stevely, 1964;Samuel et al, 1971;Maisey and Stimmler, 1972). As propranolol will control the clinical and subjective evidence of adult thyrotoxicosis (Hadden et al, 1968;Shanks et al, 1969) while awaiting the effect of radioactive iodine destruction of the thyroid, the transient nature of neonatal thyrotoxicosis suggests that this form of therapy would be useful.…”

Neonatal Hyperthyroidism

“…From 1912, when White first described thyrotoxicosis in a newborn infant, until 1971 about 40 cases have been reported (10,11). The course of neonatal thyrotoxicosis seems to follow the decay of LATS.…”