Surveillance for thyroid disease in children with type 1 diabetes mellitus

T1DM: type 1 diabetes mellitus; TSH: thyroid-stimulating hormone (thyrotropin); fT4: free thyroxine; T4: thyroxine; TPO-Ab: thyroid peroxidase antibodies; Tg-Ab: thyroglobulin antibodies.

* Measure TSH after glycemic control is first established. At least 20% of patients have transient thyroid function abnormalities at diagnosis, which resolve as diabetes is treated.

¶ fT4 or T4 should be measured if TSH is abnormal; some laboratories do this reflexively.

Δ If TPO-Ab and/or Tg-Ab are positive, they do not need to be repeated. If both tests are negative initially, they should be repeated if hypothyroidism develops.

◊ Patients with hypothyroidism and negative TPO-Ab and Tg-Ab should be further evaluated to determine the cause of hypothyroidism. Refer to UpToDate content on acquired hypothyroidism in children.

§ For subclinical hypothyroidism (elevated TSH and normal fT4 or T4), most clinicians treat if TSH is >10 mU/L or if antithyroid antibodies (TPO-Ab or Tg-Ab) are positive. For children with mild subclinical hypothyroidism (TSH between 6 and 10 mU/L) and negative antithyroid antibodies, there is some controversy about the need to treat, but such patients should be monitored closely, with repeat TSH and T4 (or fT4) in 6 months or if symptoms develop.

¥ Hyperthyroidism develops in up to 1% of children with T1DM. This usually represents Graves disease (due to TSH receptor-stimulating antibodies) or Hashimoto thyroiditis (ie, the thyrotoxic phase of chronic autoimmune thyroiditis). If fT4 or T4 are normal, the patient most likely has subclinical Graves disease. For evaluation and management of these conditions, refer to UpToDate content on Graves disease in children and adolescents.