Outcome of Sars-COV-2-related thyrotoxicosis in survivors of Covid-19: a prospective study.

Purpose: To evaluate the post- coronavirus disease-19 (COVID-19) outcome of thyroid function in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-related thyrotoxicosis.
Methods: This was a single-center prospective study involving 29 patients (11 females, 18 males; median age 64 years, range: 43-85) with thyrotoxicosis diagnosed after hospitalization for COVID-19 and then followed-up for a median period of 90 days (range: 30-120) after hospital discharge. At follow-up, patients were evaluated for serum thyrotropin (TSH), free-thyroxine (FT4), free-triiodiothyronine (FT3), TSH receptor antibodies (TRAb), thyroglobulin antibodies (TgAb), thyroperoxidase antibodies (TPOAb) and ultrasonographic thyroid structure.
Results: After recovery of COVID-19, serum TSH values significantly increased (P < 0.001) and FT4 values significantly decreased (P = 0.001), without significant change in serum FT3 (P = 0.572). At follow-up, 28 subjects (96.6%) became euthyroid whereas overt hypothyroidism developed in one case. At the ultrasound evaluation of thyroid gland, hypoecogenicity was found in 10 patients (34.5%) and in these cases serum TSH values tended to be higher than those without thyroid hypoecogenity (P = 0.066). All subjects resulted to be negative for TgAb, TPOAb and TRAb.
Conclusion: In a short-term follow-up, thyroid function spontaneously normalized in most subjects with SARS-CoV-2-related thyrotoxicosis. However, thyroid hypoecogenicity was found in a remarkable number of them and future longer-term studies are needed to clarify whether this ultrasonographic alteration may predispose to develop late-onset thyroid dysfunction.