Prospective evaluation of autoimmune and non-autoimmune subclinical hypothyroidism in Down syndrome children


Pepe G, Corica D, De Sanctis L, Salerno M, Faienza MF, Tessaris D, Tuli G, Scala I, Penta L, Alibrandi A, Pajno GB, Aversa T, Wasniewska M; Thyroid Study Group of the Italian Society of Pediatric Endocrinology and Diabetology (ISPED).

Eur J Endocrinol. 2020 Apr;182(4):385-392. doi: 10.1530/EJE-19-0823.

PMID: 31999620

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Objective: To evaluate the prevalence and natural course of autoimmune and non-autoimmune subclinical hypothyroidism (SH) in Down syndrome (DS) children and adolescents.

Design: Prospective multicenter study.

Methods: For the study, 101 DS patients with SH (TSH 5-10 mIU/L; FT4 12-22 pmol/L), aged 2-17 years at SH diagnosis were enrolled. Annual monitoring of TSH, FT4, BMI, height, and L-thyroxine dose was recorded for 5 years. Thyroid autoimmunity was tested at diagnosis and at the end of follow-up.

Results: Thirty-seven out of 101 patients displayed autoantibody positivity (group A); the remaining 64 were classified as non-autoimmune SH (group B). Group A was characterized by higher median age at SH diagnosis and by more frequent family history of thyroid disease (6.6 vs 4.7 years, P = 0.001; 32.4% vs 7.8%, P = 0.001 respectively), whereas congenital heart defects were more common in group B (65.6% vs 43.2%, P = 0.028). Gender, median BMI (SDS), height (SDS), FT4, and TSH were similar in both groups. At the end of follow-up: 35.1% of group A patients developed overt hypothyroidism (OH) vs 17.2% of group B (P = 0.041); 31.25% of group B vs 10.8% of group A became biochemically euthyroid (P = 0.02); and 37.8% of group A vs 51.5% of group B still had SH condition (P = 0.183). Logistic regression suggested autoimmunity (OR = 3.2) and baseline TSH values (OR = 1.13) as predictive factors of the evolution from SH to OH.

Conclusions: In DS children, non-autoimmune SH showed higher prevalence and earlier onset. The risk of thyroid function deterioration over time seems to be influenced by thyroid autoimmunity and higher baseline TSH values.