ESPE Abstracts

Background: Subclinical hypothyroidism is a common finding in Down syndrome (DS) patients and transition towards overt hypothyroidism can occur, but there are no predictor factors to identify patients that will need replacement therapy later in life.

Objective and hypotheses: This is a retrospective cohort study on a population of DS paediatric patients. This study was designed to evaluate possible early predictive features of hypothyroidism development.

Methods: We retrospectively evaluated 49 paediatric DS patients (31 males and 18 females). Median (IQR) age at first evaluation was 3.47 (0.5 – 15.7) years and follow-up 4.3 years (1–9). Thyroid function was described as normal (TSH 0.31–5.00 μUI/ml), subclinical hypothyroidism (TSH 5.10–10.00 μUI/ml, normal fT₄ and fT₃) or overt hypothyroidism (TSH > 10.00 μUI/ml). Autoimmune etiology was investigated through auto-antibodies positivity (AbTPO, AbTG; TRAb). Statistical analysis was performed using logistic regression and ROC curves, Mann-Whitney test, chisquare test and Odd ratio. The statistical significance was set at P<0.05.

Results: In our study 38.8% of patients (19/49) showed subclinical hypothyroidism during follow-up. Therapy with L-thyroxine was initiated in 8 patients (16.3%), who were diagnosed with overt hypothyroidism (4/8 have autoimmune thyroiditis). We found that a TSH cut-off value of 5.07 μUI/ml at first evaluation was significantly predictive of overt hypothyroidism development during follow-up (sensibility 100%, specificity 43.9%). Moreover, patients who started replacement therapy during follow-up, had significantly increased thyrotropin values at first evaluation (P<.01). Also anti-thyroid antibodies positivity resulted to be predictive of thyroid disease (P<.002). Finally, we observed that TSH > 5.07 associated with anti-thyroid antibodies positivity increased the risk of hypothyroidism of 12.6 time.

Conclusion: Our study showed that an early increase of TSH value, using as cut-off 5.07 μUI/ml, associated with auto-antibodies positivity can identify DS patients who need a more careful follow-up, since the risk of hypothyroidism seems to be higher.