1. Background

• maternal levels of TSI must be at least 5x normal to produce neonatal thyrotoxicosis thus only 1% of infants born to mothers with Graves' Disease will be affected
• may occur in the absence of clinical maternal hyperthyroidism
• clinical onset, severity, and course may be affected by the concomitant transplacental passage of TSH-inhibiting antibodies (TBIAb) and antithyroid medications (both tend to delay the onset of thyrotoxicosis)

1. In Utero

• fetal tachycardia in 3rd trimester (>160 beats/min)
• many are premature

2. Neonatal

• thyrotoxicosis usually evident within hours of birth although may be delayed for 4-6 weeks

  1. Thyrotoxicosis

  • exophthalmos, flushing, hyperactive, irritable, tremor
  • tachycardia, tachypnea, hypertension, elevated temperature
  • arrhythmias, congestive heart failure
  • vomiting and diarrhea with weight loss despite a voracious appetite
  • hepatosplenomegaly, jaundice
  • thyroid - goiter +/- airway obstruction

1. Serum

• increased T3, total and free T4; decreased TSH
• increased maternal TSI levels
• hyperbilirubinemia, prolonged PT, thrombocytopenia

2. Imaging Studies

1. Medical

2. Natural History

• usually remits spontaneously within 6-12 weeks but may rarely persist for longer or years depending on the level of TSI
• 16% mortality rate