TSH neurosecretory dysfunction (TSH-nd) in Down syndrome (DS): low risk of progression to Hashimoto's thyroiditis.

Introduction: Patients with Down syndrome (DS) often have elevated TSH (hypothalamic origin), which is called TSH neurosecretory dysfunction (TSH-nd). In these cases, there is slight elevation in TSH (5-15 µUI/mL), with normal free T4 and negative thyroid antibodies (AB).

Objective: To recognize the risk of progression to Hashimoto's thyroiditis (HT).

Subjects And Methods: We retrospectively analyzed 40 DS patients (mean age = 4.5 years), followed up for 6.8 years.

Results: HT was diagnosed in 9/40 patients, three early in monitoring, and six during evolution. In 31/40 patients, TSH-nd diagnosis remained unchanged over the years, with maximum TSH values ranging from 5 to 15 µUI/mL. In this group, free T4 also remained normal and AB were negative. There was a significant TSH reduction (p = 0.017), and normal TSH concentrations (< 5.0 µUI/mL) were observed in 29/31 patients, in at least one moment. No patient had TSH > 15 µUI/mL.

Conclusion: DS patients with TSH-nd present low risk of progression to HT (10% for females and 6% for males).