Intrauterine diagnosis and treatment of fetal goitrous hypothyroidism

Abstract

We present two cases of fetal hypothyroidism with goiter which were successfully diagnosed and treated in utero. In both cases, ultrasonographic examination demonstrated a bilobed solid anterior neck mass with increased vascularity compatible with enlarged thyroid gland. Fetal blood sampling revealed hypothyroidism. Intra-amniotic injection of L-thyroxin caused a reduction in thyroid gland size and enabled vaginal delivery without complication. In the first case, maternal thyroid hormone levels and autoantibodies were normal and the neonate had hypothyroidism suggesting the diagnosis of dyshormonogenesis. In the second case, the fetus had transient hypothyroidism, which resolved spontaneously after delivery. Maternal thyroid function tests and autoantibodies were normal and both the mother and neonate had normal urinary iodine, excluding the diagnosis of iodine deficiency or excess. Thus, we believe that transplacental transfer of undetermined factors might be a cause of transient congenital hypothyroidism. Also, we reviewed the literature and described controversial issues regarding the management of fetal goiter.

Graves’ disease complicated by fetal goitrous hypothyroidism treated with intra-amniotic administration of levothyroxine

“…Fetal goitre is a rare entity,1–3 and, in most cases, is associated with maternal hyperthyroidism 7. Antithyroid drugs and, more rarely, maternal inhibitory TRAbs pass through the placental barrier and may cause fetal hypothyroidism 3 7. In our case, at the first cordocentesis performed, the evaluation of TRAbs in the fetal cord was 3.3 IU/L, making the diagnosis of hypothyroidism subsequent to the placental pass of maternal inhibitory thyroid antibodies unlikely.…”

“…Antithyroid drugs are the treatment of choice in Graves’ hyperthyroidism, and they should be used at the smallest possible dose in order to avoid overtreatment, which can induce fetal hypothyroidism and goitre 11. Fetal goitre is a rare entity,1–3 and, in most cases, is associated with maternal hyperthyroidism 7. Antithyroid drugs and, more rarely, maternal inhibitory TRAbs pass through the placental barrier and may cause fetal hypothyroidism 3 7.…”

“…The most common cause of fetal goitrous hypothyroidism is maternal antithyroid therapy for Graves’ disease (GD) 2 6. Fetal goitre can obstruct the trachea and the oesophagus and may cause polyhydramnios, preterm labour, neonatal asphyxia and death 2 6–8. Moreover, if the goitre is due to hypothyroidism, it can be associated with motor and cognitive deficits and impaired intellectual development 4 7 9…”

Iodine-Induced Fetal Hypothyroidism: Diagnosis and Treatment with Intra-Amniotic Levothyroxine

“…The patient elected to proceed with serial intra-amniotic levothyroxine injections (500 µg every 2 weeks). This dose was chosen in order to deliver approximately 10 µg/kg/day to the fetus, assuming 10% of the medication was swallowed and absorbed [9, 20, 21]. The decision was made to also treat the mother with 100 µg of levothyroxine daily due to the concern that abrupt discontinuation of the maternal thyroid supplement may induce maternal hypothyroidism, which would potentially compound the already severe fetal hypothyroidism.…”

“…Intra-amniotic levothyroxine injections have been utilized to treat fetal hypothyroidism and goiter [6-8]. However, the impact of intrauterine therapy on neurodevelopmental outcome remains controversial [7, 9]. Some evidence suggests that waiting until the postnatal period to administer treatment leaves the infant at risk for impaired neurodevelopment [1, 7, 10-12].…”