Thyroid Abnormalities in a Prospective Longitudinal Cohort of Pediatric Patients following SARS-CoV-2 infection.

Introduction Thyroid dysfunction has been reported in adults and children following COVID-19. We evaluated thyroid function in children following SARS-CoV-2 infection compared to uninfected controls over at least one year of follow up. Methods Thyroid function tests (TSH, Free T4) were analyzed in pediatric participants enrolled in the Pediatric SARS CoV-2 Long Term Outcome Study (PECOS), a diverse, prospective, longitudinal, multicenter cohort study. Assessments were conducted at baseline, and at follow-up visits for both infected and uninfected cohorts. Results Among 505 participants with non-missing data at baseline and 12-months, no significant differences were noted in proportion of TSH or Free T4 abnormalities among the infected vs. uninfected participants. Among infected participants 5% (25/464) developed subclinical hypothyroidism (high TSH and normal free T4) following recovery from SARS-CoV-2 infection, compared with 4.9% (2/41), a similar proportion in the uninfected group (p=1). Within the infected subgroup during 36-month follow up, three were treated with levothyroxine for persistent TSH elevation or goiter and 2/3 had positive thyroid antibodies consistent with autoimmune thyroid disease. Neither the number of SARS-CoV-2 reinfections nor number of COVID-19 vaccination status predicted the occurrence of TSH abnormalities. Conclusion Children infected with COVID-19 did not have increased thyroid dysfunction compared to uninfected controls during 12 months of follow up. A small proportion (5%) developed mild subclinical hypothyroidism that was transient in both groups, and only 3 infected participants (with TSH>10mcIU/mL or thyromegaly) needed levothyroxine replacement after 36-month follow up in this subgroup. Risk of thyroid autoimmunity compared to the uninfected population needs further study.