3. Discussion
Several reports have described a relationship between COVID-19 and thyroid disorders such as subacute thyroiditis, autoimmune thyroiditis and Graves’ disease [4–6]. In a retrospective single-center study by Lania[7], 20.2% in their cohort were found to have thyrotoxicosis. Serum TSH levels were inversely correlated with age and IL-6 levels.
Autoimmune thyroiditis is one of the most common thyroid disorders in South East Asia [8,9]. In this condition, detectable anti-thyroid antibodies such as anti-thyroid peroxidase (anti -TPO) and anti-thyroglobulin antibodies (anti -Tg) are present in the seraof most patients. Anti -Tg antibodies were undetectable in our patient pre-COVID-19 infection, but were found after the infection had resolved, as in a number of similar cases in other countries [10].
Graves’ disease is the most common cause of hyperthyroidism in South East Asia [8,9]. It is also an autoimmune thyroid disease in which the presence of thyroid receptor antibody (TRAb) and a low or undetectable TSH level are typical. Most reported case series of hyperthyroidism during active COVID-19 infection suggest that a destructive viral thyroiditis contributes to the clinical presenation of subacute thyroiditis [4–7,11–13]. An autopsy study in COVID-19 patients showed destruction of the follicular and parafollicular cells of the thyroid [14]. Our literature search revealed reports of thyroid disorders occurring after COVID-19 infection are sparse and as far as we are aware, this is the first case of new-onset Graves’ disease post COVID-19 in Vietnam. However, several cases reported recently have shown new-onset of Graves’ disease as the cause of hyperthyroidism in patients after COVID-19 infection [15–17]. Reelevant demographic and clinical characteristics of each included patient are summarized in Table 2

Table 2

Description of the demographic characteristics and clinical presentation of COVID-19 triggered Graves’ disease