ESPE Abstracts

Down syndrome (DS) is the most common chromosomal disorder in live births (1/1500-1/700) and caused by a meiotic nondisjunction (trisomy 21). DS is associated with an increased risk of thyroid disorders in addition to other systemic problems. In this study, we aim ed to investigate the thyroid hormone profiles and associated autoimmune diseases in DS.

Material and Method: DS patients, aged 0-18 years, who were followed for thyroid problems between 2001-2023, were evaluated retrospectively. Thyroid-stimulating hormone (TSH), free T4 (f-T4), thyroid autoantibodies and the presence of other autoimmune diseases (AD) were assessed.

Results: One hundred DS patients (52 girls) with thyroid dysfunction were included. 97 patients had hypothyroidism (mean age: 2.1±3.6 years), 3 patients had hyperthyroidism (mean age: 3.9±0.9 years). Among 58 patients ≤1-year with hypothyroidism (mean age: 0,2±0,2 years), 23 (40%) had TSH of >20 µIU/mL. When the thyroid volume and f-T4 SDS levels were compared between patients with TSH <20 and >20, there was no statistically significant difference in total thyroid volume (0.54±0.38 vs. 0.36±0.26, p:0.24) or fT4 SDS levels (p: 0.44). There was no statistical significant difference in TSH and sT4 SDS levels between patients ≤1-year and those >1-year. For 39 hypothyroid patients who were older than 1-year, mean age and TSH levels at diagnosis were 5.1±4.3 years and 18.7±7.2 µIU/mL, respectively. Among these, TSH levels were >20µIU/mL in 4, and >10µIU/mL in 11 patients. Furthermore, f-T4 SDS levels were statistical significant higher in patients with TSH <10 than >10 (0.07±1.5 vs.-1.2±2.02, p: 0.04). In whole group, 10 patients had hypothyroxinemia (sT4 <-2SDS) however, TSH values were similar in hypothyroxinemia and euthyroxinemia groups (median:33 min:3.7 max:398, median:10.47 min:4.9 max:153, respectively, p:0.75). Thyroid autoantibodies were detected as positive in 7 out of 22 patients (31.8%). Additionally, 2 patients with thyroid autoimmunity transitioned from hypothyroidism to hyperthyroidism, with one returned to hypothyroidism later on. Non-thyroid ADs were detected in 9% of the patients. Specifically; celiac disease was found in 3 patients, alopecia areata in 2, psoriasis in 2, ITP in 1 and vitiligo in 1.

Conclusion: Our study demonstrates the thyroid problems in DS exhibit unique features with TSH elevation showing a disparity from f-T4 levels. These inconsistencies in DS patients cannot be explained by current knowledge and require further investigations. Additionally, careful monitoring for other AD, along with thyroid autoimmunity is recommended.