Higher SARS-CoV-2 viral loads correlated with smaller thyroid volumes on ultrasound among male COVID-19 survivors

Lui, David Tak Wai; Fung, Matrix Man Him; Chiu, Keith Wan Hang; Lee, Chi Ho; Chow, Wing Sun; Lee, Alan Chun Hong; Tam, Anthony Raymond; Pang, Polly; Ho, Tip Yin; Fong, Carol Ho Yi; Loong, Connie Hong Nin; Wong, Wade Wei; Lee, Cassandra Yuen Yan; Law, Chun Yiu; To, Kelvin Kai Wang; Lam, Ching Wan; Tan, Kathryn Choon Beng; Woo, Yu Cho; Hung, Ivan Fan Ngai; Lam, Karen Siu Ling; Lang, Brian Hung Hin

PURPOSE: Thyroid dysfunction, including thyroiditis, is well recognized in COVID-19 patients. We evaluated thyroid ultrasonographic features among COVID-19 survivors, which are less well known. METHODS: Adult COVID-19 survivors without known thyroid disorders who attended dedicated COVID-19 clinic underwent thyroid ultrasonography and assessment of thyroid function and autoimmunity. Adults admitted for acute non-thyroidal surgical problems and negative for COVID-19 were recruited as control. SARS-CoV-2 viral load (VL) was presented as the inverse of cycle threshold values from the real-time reverse transcription-polymerase chain reaction of the respiratory specimen on admission. RESULTS: In total, 79 COVID-19 patients and 44 non-COVID-19 controls were included. All abnormal thyroid function tests during acute COVID-19 recovered upon follow-up. Thyroid ultrasonography was performed at a median of 67 days after acute COVID-19. The median thyroid volume was 9.73 mL (IQR: 7.87–13.70). In multivariable linear regression, SARS-CoV-2 VL on presentation (standardized beta −0.206, p = 0.042) inversely correlated with thyroid volume, in addition to body mass index at the time of ultrasonography (p < 0.001). Sex-specific analysis revealed similar results among men but not women. Eleven COVID-19 patients (13.9%) had ultrasonographic changes suggestive of thyroiditis, comparable to non-COVID-19 patients (p = 0.375). None of these 11 patients had isolated low thyroid-stimulating hormone levels suggestive of thyroiditis at initial admission or the time of ultrasonography. CONCLUSIONS: Higher SARS-CoV-2 VL on presentation were associated with smaller thyroid volumes, especially in men. Further research is suggested to investigate this possible direct viral effect of SARS-CoV-2 on the thyroid gland. There was no increased rate of ultrasonographic features suggestive of thyroiditis in COVID-19 survivors.