TRANSIENT NEONATAL HYPERTHYROIDISM BY TRA NSPLACENTAL PASSAGE OF TSH RECEPTOR ANTIBODIES

Background. Neonatal hyperthyroidism is a relatively rare condition. I t can be severe and difficult to treat when the maternal hyperthyroidi sm has recently been recognized Case report. A baby was born at 37 wee ks of gestational age to a mother whose hyperthyroidism was only suspe cted at the 34th week The mother was not given propylthiouracil until the day before delivery. At birth, the newborn presented with meconial fluid; it weighed 2,380 grams, was 46 cm long and had a head circumfe rence of 32 cm. Clinical examination showed exophthalmos, tachycardia, hepatosplenomegaly, restlessness, moderate goiter and premature crani osynostosis. Laboratory data showed elevated serum free T4 (76 pmol/l) , unmeasurable TSH, and the presence of thyroid-stimulating immunoglob ulins. The infant was given propranolol (10 mg/day), and carbimazol (3 .75 mg/day) from day 13. Clinical and biological improvement allowed t he carbimazol to be stopped at 1 month. A relapse was treated with car bimazol plus L-thyroxine Both drugs were discontinued at the age of 4 months. At 12 months, the baby is perfectly well and has developed nor mally Conclusion. This transient thyrotoxicosis was due to the transpl acental passage of TSH receptor antibodies. Its management was difficu lt because the mother was treated late during her pregnancy.