My seven year old son with type 1 diabetes had incorrect thyroid levels. During his recent annual blood work, the following test results were abnormal. TSH 4.360, thyroid peroxidase antibody 2.00, antithyroglobulin 119. Is this definite hypothyroidism? His T3 is 33 percent and T4 is 8.0, free T4 index is 2.1. I hope this is enough information for you to answer. What other tests would you recommend in this case?

All the tests have been done correctly. This is euthyroid thyroiditis. His thyroid gland is functioning normally with normal T4 and normal TSH, perhaps a tad bit higher than one would like but probably at the upper range of the normal. Most of us would prefer values in the 1-2 range but this does usually not need any thyroid hormone treatment unless there are symptoms of hypothyroidism or a very large goiter. Some people treat goiters, even with normal thyroid functions. Positive thyroid antibodies make the diagnosis of Hashimoto’s thyroiditis, which occurs about 20-40 percent of the time in type 1 diabetes. One doesn’t cause the others but they are associated since both are autoimmune phenomenon. Usually, just following these values with repeat values every 4-56 months would be sufficient as long as there is normal growth and no change in thyroid gland size, no thyroid related symptoms etc.

Ask if screening for celiac disease has also been done since the presence of two autoimmune disorders should produce high suspicion for a third, like celiac, tested with transglutaminase antibody.

You may also wish to read Insulin-Dependent Diabetes in Children, Adolescents and Adults by Ragnar Hanas, M.D., page 205, for a brief discussion of thyroid disease.

SB
Additional comments from Brenda Hitchcock:

See also Thyroid Disease and Diabetes: Patient Education Sheet.

BH