Assessment of Thyroid Status and Six Months of Follow-Up in COVID-19 Patients: A Prospective, Observational Study

Background Globally, the COVID-19 pandemic inflicted considerable morbidity and mortality. It has become a systemic illness that affects several body organs. The primary pathway for the SARS-CoV-2 virus to enter cells is the angiotensin-converting enzyme 2 (ACE2) receptor, and it uses transmembrane serine protease 2 (TMPRSS2) for S protein priming. Thyroid follicular cells have been found to express ACE2 and TMPRSS2 at even higher levels than those found in the lungs. The objective of the study was to assess and determine the six-month clinical outcome of thyroid dysfunction in COVID-19 patients. Methods This prospective, observational study was carried out in the COVID-19 unit of Bangabandhu Sheikh Mujib Medical University, Dhaka, Bangladesh. Forty-eight hospital-admitted COVID-19 reverse transcription-polymerase chain reaction (RT-PCR)-positive patients were included as per inclusion and exclusion criteria, and there was no control group. All admitted patients were classified into non-severe (mild, moderate) and severe (severe and critical) disease as per national guidelines. Baseline laboratory tests for thyroid-stimulating hormone (TSH), free T3, and free T4 were done on admission. The patients were again categorized according to their thyroid status. Further evaluation was done by performing autoantibody tests (TSH receptor Ab, anti-thyroid peroxidase Ab, anti-thyroglobulin Ab). The patients were followed up in the first month and sixth month to see disease progression and outcomes. Results Age and comorbidities were associated with an increased risk of severe disease. A total of 35 (73%) patients had comorbidities, 23 (49%) had multiple comorbidities, and 12 (24%) had single comorbidities. All patients (n=48) presented with fever and cough; 45 (94%) patients had fatigue, palpitations were present in 35 (73%) patients, and dyspnea in 32 (67%) patients. The difference in mean values of TSH, FT4, and FT3 among severe and non-severe groups was found to be significant. Most of the patients (n=36; 75%) were in a euthyroid state at baseline. Among the rest, 25% had thyroid dysfunction, including one (2.08%) who had subacute thyroiditis and eight (16.67%) who had euthyroid sick syndrome, which was higher in the severe group (14.59%). Three (6.24%) patients were autoantibody-positive and were diagnosed as having Hashimoto's thyroiditis in the form of primary hypothyroidism (2.08%; n=1) and subclinical hypothyroidism (4.16%; n=2). The Spearman correlation coefficient showed a strong negative correlation between severity and TSH (rs = -0.71) and moderate positive correlations between severity and free T3 (rs = 0.63) and free T4 levels (rs = 0.53). Follow-up at the first month showed that 44 (91.96%) returned to a euthyroid state, and at six months, 45 (93.7%) returned to a euthyroid state. Conclusion Thyroid hormone levels appear to change and recover gradually and spontaneously. Most patients have normal thyroid function status during COVID-19 infections, but a considerable number of patients can develop euthyroid sick syndrome in severe COVID-19 infections, from which they recover spontaneously.