All newborn screening laboratory values were normal except for an elevated level of thyrotropin (>150 mIU/L) and a free thyroxine level of 0.3 ng/dL (to convert to picomoles per liter, multiply by 12.871). The antithyroglobulin antibody level was within the normal range. The thyroglobulin level was very elevated (14 251 ng/mL [to convert to micrograms per liter, multiply by 1.0]). A pertechnetate thyroid scan showed diffuse radiotracer uptake bilaterally in the thyroid. The dimensions of the thyroid gland corresponded to the neck masses noted on MRI, confirming the diagnosis of fetal goitrous hypothyroidism. On further investigation, the mother reported a high intake of seaweed salad and sushi in the third trimester of pregnancy, which suggested high fetal iodine exposure from these foods, resulting in hypothyroidism and goiter. Of note, the maternal urinary iodine levels were slightly above normal limits.
Radiology Quiz Case 2: Diagnosis. Arch Otolaryngol Head Neck Surg. 2010;136(10):1034-1035. doi:10.1001/archoto.2010.158-b