312 - Iodine Deficiency Revisited: A Case Report Of Hypothyroidism In A Child In The United States

Publication Number: 312.5645

Shovana Ghimire, Southern Illinois University School of Medicine, Springfield, IL, United States; Sandesh Gyawali, Ascension St Francis Hospital, Evanston, IL, United States; Avani Ganta, Southern Illinois University School of Medicine, Springfield, IL, United States

Background: Iodine deficiency is a historical cause of hypothyroidism in the pediatric population and is now a rare entity due to the fortification of food items in the U. S. Dietary restrictions can limit iodine intake in children resulting in iodine deficiency and hypothyroidism. Here, we present a rare case of a 7-year-old Caucasian male presenting with symptoms of severe hypothyroidism due to iodine deficiency.

Objective: To discuss a rare case of dietary iodine deficiency causing hypothyroidism in U.S. and its diagnostic approach.

Design/Methods: The patient presented as a referral to our endocrine clinic for evaluation of severe hypothyroidism. On presentation, his serum thyroid stimulating hormone (TSH) was >150 μIU/mL (0.60-4.84). He had fatigue and increased daytime sleepiness, vision issues along with poor growth, a gradual decrease in weight; from 54th centile to 2nd centile and height; 45th centile to < 1 centile without evidence of height acceleration over the past 4 years. He had severe dietary preferences likely related to sensory processing issues given his history of global developmental delay. Examination showed normal vital signs, a non-enlarged thyroid gland, and a normal cardiovascular, skin/hair examination. Eye examination showed limited upward eye movement, along with peripheral vision defect.

Results: Workup showed vitamin A level of < 2.5 μg/dl (12.8-81.2 μg/dl), serum TSH of 295 μIU/mL (0.60-4.84 μIU/mL), free T4 (fT4) of 0.3 ng/dL (0.90-1.67 ng/dL), free T3 (fT3) of 2.7 pg/mL, urine iodine concentration (UIC) of 23.0 μg/L (26-705 μg/L). Serum TSH receptor antibody, thyroid microsomal antibody and thyroglobulin antibody were negative. Brain MRI was done due to the eye findings, to rule out any pituitary abnormalities, which resulted normal. He was started on levothyroxine 12.5 mcg and supplemental iodine 100 mcg daily, while being managed for dietary issues. One month later his serum TSH levels were 1.150 μIU/mL. UIC levels were 232.6 μg/L after 6 months. We stopped his iodine supplementation as the diet improved.

Conclusion(s): Most Americans get iodine from iodized salt, seafood, and dairy products such as milk, cheese, and yogurts. In children with dietary restrictions, iodine deficiency seems to be a reemerging cause of hypothyroidism. It is important to assess the diet and urinary iodine concentration when patients present with severely abnormal thyroid function tests, normal thyroid antibodies and/or with no physical exam findings. A spot urine iodine concentration should be considered in children with hypothyroidism and dietary restrictions to evaluate for iodine deficiency.