IMPE Abstracts

Introduction: Maternal Graves' disease (GD) is the most common cause of neonatal hyperthyroidism. Which by definition is transient and self-limited. There is also an infrequent cause of non-autoimmune persistent neonatal hyperthyroidism due to activating mutations in the TRH receptor (TSHR), both familial (FNAH) and sporadic (PSNAH), or to Protein G Mutation (Macune Albright Syndrome (GNAS). Neonatal screening for thyroid disease focuses on prevention of neurocognitive developmental delay, and does not recognize the prevalence of thyroid hyperfunction, which includes: bone age advancement, craniosynostosis, as well as exophthalmus and a sustained hypercatabolic and hyperadrenergic state that can lead to severe cardiovascular complications.

Objective: A clinical case of late-diagnosed FNAH and its consequences is presented, in order to recognize and treat the signs and symptoms of non-immune neonatal hyperthyroidism, thus making timely diagnosis and treatment.

Clinical case: 10-month-old male infant with a history of PTNB at 35 weeks non-severe PEG born by emergency cesarean section for fetal tachycardia, with neonatal screening (-)with TSH 0.1 uIU/mL compatible from RN period with thyroid hyperfunction. Evolves with persistent hypercatabolism without failure to thrive, with exophthalmia and ptosis from 3 months, severe craniosynostosis, RDSM motor area with hypotonia. At 5 months, hyperthyroidism was diagnosed with TSH <0.005 uUI/mL FT4 <7.7 ng/dL anti-TPO antibodies, TG and TRAbs (-) that did not respond to maximum doses for age of methimazole, and significant advancement of bone age (4 years for 7 months). Thyroid ultrasound shows hypodevelopmentof the left lobe, and the rest of the gland increased in volume and hyperemia. At 12 months of age due to poor response to methimazole, a total thyroidectomy was performed with postoperative normalization of the thyroid profile and hypercatabolic state. Genetic study for TSHR and GNAS, pending result. Paternal family presents cases of thyroid hyperfunction in all generations compatible with suspicion of FNAH.

Conclusions: In infants with craniosynostosis, RDSM, advanced bone age, and tachycardia, a diagnosis of persistent hyperthyroidism should be considered, as well as a study of its genetic causes. Detailed personal and family medical history is important, especially in the face of poor response to medical treatment and absence of antibodies. Early thyroidectomy is the treatment of choice at this age given the poor response to antithyroid drugs to avoid neurodevelopmental consequences and cardiovascular complications