Thyroid Function, Inflammatory Response, and Glucocorticoids in COVID-19

Clinical use of thyroglobulin: not only thyroid cancer

Thyroglobulin (TG) is a dimeric glycoprotein produced exclusively by mature thyroid tissue and stored within the follicular lumen. It is essential for the organification of iodine and the production of thyroid hormones. The concentration of TG in the bloodstream varies between individuals and depends on factors such as thyroid mass, stimulation of the gland by thyrotropin or autoantibodies, and tissue destruction. TG is essential to monitor patients with differentiated thyroid cancer; however, its use is not limited only to this clinical entity. Measurement of circulating TG can provide better insight into numerous clinical scenarios, such as destructive thyroiditis, presence of ectopic thyroid tissue, thyroid trauma, factitious thyrotoxicosis, or iodine nutrition. Lately, TG has found its new clinical use in immune checkpoint-related thyroid dysfunction. TG measurement should be performed carefully in patients with antithyroglobulin antibodies due to possible laboratory interferences. In this review, we offer a summary of current knowledge about the clinical use of TG and the implications it brings to daily practice.

An unusual evolution of thyroid function after therapeutic plasma exchange in Graves' disease with cholestatic jaundice: A case report

RATIONALE

Methimazole (MMI) is the first-line agent in the treatment of hyperthyroidism. However, rare but severe cholestatic jaundice may occur. Therapeutic plasma exchange (TPE) may provide an alternative treatment for such patients and they received thyroidectomy/radioactive iodine ablation or continued oral anti hyperthyroidism medication immediately after TPE session in the reported literatures. The case reported here is, to our knowledge, the first to describe the long interval between anti hyperthyroidism therapy and TPE in such patients.

PATIENT CONCERNS

A 49-year-old Chinese woman had developed worsening jaundice 3 weeks after receiving methimazole (20 mg/day) for the treatment of hyperthyroidism secondary to Graves' disease (GD). Additionally, she had a 2-year history of type 2 diabetes.

DIAGNOSIS

Hyperthyroidism secondary to GD, MMI-induced severe cholestatic jaundice and type 2 diabetes.

INTERVENTIONS

Methimazole was discontinued and the patient received 3 times of TPE, about 3-month glucocorticoid treatment, insulin administration accordingly and other conventional liver-protecting therapy.

OUTCOMES

Her thyroid function was stabilized with small dose of thyroxine substitution and euthyroid status persisted after thyroxine discontinuation until hyperthyroidism recurred 7 months later while her cholestatic jaundice was eventually recovered by about 3-month glucocorticoid therapy.

LESSONS

Due to the complex interplay between liver function and thyroid hormones, there may be unusual changes of thyroid function in GD patients with severe liver injury after TPE. By this case, we want to highlight the importance of a closely following up of thyroid function in order to deliver appropriate health suggestions for patients.

Thyroglobulin levels in COVID-19-positive patients: Correlations with thyroid function tests, inflammatory markers, and glucocorticoid use

COVID-19 often results in generalized inflammation and affects various organs and systems. Endocrine research focused on the possible sequelae of COVID-19, with special interest given to the thyroid gland. Clinical problems such as thyroid function in non-thyroidal illness (NTI), autoimmune thyroiditis, and COVID-19-related subacute thyroiditis (SAT) quickly gained wide coverage. Thyrotoxicosis of various origins leads to the release of peripheral thyroid hormones and thyroglobulin (TG), the main glycoprotein contained within the thyroid follicular lumen. In our study, we evaluated TG levels in COVID-19-positive patients and investigated the possible relationships between TG, thyroid function tests (TFTs), and inflammatory markers. Our approach included separate subanalyses of patients who received and those who did not receive glucocorticoids (GCs). In the entire population studied, the concentration of TG tended to decrease with time (p<0.001; p1,2 = 0.025, p1,3 = 0.001, p2,3 = 0.003), and this pattern was especially clear among patients treated with GCs (p<0.001; p1,2=<0.001; p1,3=<0.001; p 2,3=<0.001). The concentration of TG differed significantly between patients treated and those not treated with GC at the second and third time points of observation (p=0.033 and p=0.001, consecutively). TG concentration did not differ between the patients with normal and abnormal TFTs. The correlations between TG, TFTs, and inflammatory markers were very limited. 19 patients had elevated TG levels, but a TFT pattern suggestive of thyrotoxicosis was not common in this group. There were no statistically significant differences between patients who met and those who did not meet the predefined combined primary endpoint.

Correlation between Thyroid Responses and Inflammatory Cytokines in Critically Ill COVID-19 Patients

Mechanisms involved in thyroid dysfunction in critically ill coronavirus disease 2019 (COVID-19) patients are not clear. Our objective was to correlate the thyroid response with the pro- and anti-inflammatory cytokines profile in critically ill COVID-19 patients. This was a prospective single-center study. We studied the relationship between continuous variables by using Pearson correlation and simple linear regression. Multiple logistic regression analysis was performed to analyze the factors independently associated with mortality. Seventy-eight patients were included in the study at intensive care unit (ICU) admission and 72 had a measurement of the thyroid and inflammatory profile at day 5. No significant correlations were found between thyroid stimulating hormone (TSH), free triiodothyronine (fT3) and free thyroxine (fT4) and inflammatory cytokines at ICU admission. At day 5, fT4, was inversely correlated with IL-10 (p = 0.035). IL-10 was associated with maximum lactate (p < 0.001) and SOFA score values (p = 0.012). The multiple logistic regression analysis showed that there was a significant relationship between IL-10 (day 5) and in-hospital mortality after adjusting by age and severity of illness. In conclusion, we found that the thyroid hormone profile and inflammatory cytokines had a weak correlation at ICU admission. Associations of interest between fT4 and IL-10 were found at day 5. IL-10 at day 5 was found to be correlated with low fT4 and markers of organ failure and death.

Thyrotropin Levels in Patients with Coronavirus Disease 2019: Assessment during Hospitalization and in the Medium Term after Discharge

BACKGROUND

The objectives of this study were (1) to compare TSH levels between inpatients with critical versus non-critical coronavirus disease 19 (COVID-19), and (2) to describe the status of TSH levels three months after hospitalization.

METHODS

We collected data on adult patients hospitalized with COVID-19 at Amiens University Hospital. We compared TSH levels between inpatients with critical (intensive care unit admission and/or death) versus non-critical COVID-19. Thereafter, survivors were invited to return for a three-month post-discharge visit where thyroid function tests were performed, regardless of the availability of TSH measurement during hospitalization.

RESULTS

Among 448 inpatients with COVID-19, TSH assay data during hospitalization were available for 139 patients without prior thyroid disease. Patients with critical and non-critical forms of COVID-19 did not differ significantly with regard to the median (interquartile range) TSH level (0.96 (0.68-1.71) vs. 1.27 mIU/L (0.75-1.79), p = 0.40). Abnormal TSH level was encountered in 17 patients (12.2%); most of them had subclinical thyroid disease. TSH assay data at the three-month post-discharge visit were available for 151 patients without prior thyroid disease. Only seven of them (4.6%) had abnormal TSH levels. Median TSH level at the post-discharge visit was significantly higher than median TSH level during hospitalization.

CONCLUSIONS

Our findings suggest that COVID-19 is associated with a transient suppression of TSH in a minority of patients regardless of the clinical form. The higher TSH levels three months after COVID-19 might suggest recovery from non-thyroidal illness syndrome.