ESPE Abstracts

Introduction: The impact of COVID-19 on the thyroid axis is still unclear. The most recent studies have presented contradictory findings. Theoretically, both direct toxic effects and indirect inflammatory responses can influence thyroid functions. A limited number of studies conducted in pediatric patients have revealed cases of hypothyroidism, hyperthyroidism, and nonthyroidal illness syndrome occurring during the COVID-19 infection.

Objectives: Our goal was to investigate the acute effects of COVID-19 on thyroid function and determine whether these effects persisted during the recovery process in pediatric patients.

Methods: Inclusion criteria included pediatric patients with positive COVID-19 test results, with the exception of those with preexisting thyroid disease and those who lacked either free thyroxine (fT4) or thyrotropin (TSH) measurements prior to the onset of COVID-19. Thus, this study included thyroid function tests at three time points: before COVID-19 (baseline thyroid function fT4 and TSH), during COVID-19 infection (infection), and after the infection resolved (post-infection). Infection and post-infection tests also comprised free triiodothyronine (fT3) and thyroglobulin (TG).

Results: 41 patients were included, 39% were boys, and the mean age was 8.23±5.35 years. Most patients (85.4%) presenting with COVID-19 were euthyroid, one with overt hypothyroidism, one with central hypothyroidism, and four with subclinical hypothyroidism. During the COVID-19 infection period, TSH and fT4 measurements showed a statistically significant reduction compared to baseline (P <0.001). Post-infection TSH and fT4 measurements increased compared to the infection period and recovered close to baseline. fT3 levels were also significantly lower during the infection period compared to post-infection measurements (P <0.001). According to COVID-19 severity, 29.2% were mild and 70.8% were moderate. Although statistically not significant, fT4, fT3, and TSH levels were lower in moderate patients compared to mild patients. However, TG levels were significantly higher in moderate patients (P = 0.01).

Conclusion: The majority of children with COVID-19 exhibit normal thyroid function. We detected slight decreases in TSH and fT4 during the infection period compared to baseline and lower infection fT3 levels compared to post-infection consistent with a nonthyroidal sickness condition, and thyroid function tests at the post-infection period showed a rebound to almost the baseline levels. Lower fT4 and fT3 levels were found in moderate infection than in mild infection albeit not significant. Higher TG levels in moderate patients compared to mild patients may suggest the body's increased attempt to restore normal serum thyroid hormone levels to enhance disease prognosis and outcomes as the severity of Covid-19 increases.