ESPE Abstracts

Context: Maternal Graves’ disease (GD) may lead to not only thyrotoxicosis but also hypothyroidism in neonates. We describe a case of transient central hypothyroidism (CH) due to undiagnosed maternal GD.

Case presentation: A 4-month old Japanese girl visited our hospital for the treatment of hypothyroidism. She was born after 37-week gestation, weighting 2320g. She developed hypoglycemia and admitted to the prior hospital. She exhibited hypothyroxinemia without elevation of thyroid-stimulating hormone (TSH) at 33-day old (free-T4: 0.6 ng/dL, TSH: 1.05 μIU/mL). Her thyroid was proved to be normal both in size and in location by ultrasonography. Thereafter, she underwent 5 μg/kg/day of oral levothyroxine (L-T4) and referred to our hospital. Laboratory data in the prior hospital indicated CH. We evaluated her anterior pituitary functions. Although we could not evaluate TSH secretion accurately because of L-T4 supplementation, it showed impaired secretion (peak value of 0.186 μIU/mL). The result indicated isolated TSH deficiency. She showed no increase in L-T4 demand despite weight gain. We continued her treatment by the same dose as it was started. When she was 5-month old, her mother was made a diagnosis of GD. Her struma was mild and no other suggestive symptoms were observed. However, it was revealed that she had noticed tachycardia and slight tremor from the early weeks of pregnancy. These facts showed that the girl might be exposed to thyrotoxicosis through almost whole pregnancy period, indicating that her thyrotroph function was suppressed and this dysfunction may be transient. Afterward, we decreased L-T4 carefully. Her thyroid function remained normal and adverse events such as growth retardation were not observed. She was discontinued the drug at 17-month old successfully. A thyrotropin-releasing hormone challenge test revealed normal reaction of TSH.

Discussion: Our case showed transient CH. Although the pituitary function showed the possibility of isolated TSH deficiency, it is rather rare condition. The diagnosis of her mother’s disease indicated transient thyrotroph suppression. The mother’s objective symptoms were mild, and she thought her symptoms as effects of pregnancy. These resulted in delayed diagnosis of GD. If her thyroid were checked when the child’s hypothyroidism was noticed, the etiology might have become apparent earlier.

Conclusion: Maternal GD may cause transient central hypothyroidism of the child. We recommend that mothers whose neonates have thyroid dysfunction should be routinely evaluated their own thyroid. This may lead accurate diagnosis of their child’s disease.