ABSTRACT
Introduction: Non-thyroidal illness syndrome (NTI), (decreased T3 and/or T4 without increased TSH), has been reported in COVID-19 infection. In patients admitted with COVID-19 we found classic NTI presentation and a high prevalence of low T3, high freeT4 (FT4) and normal TSH, which could represent a different presentation of NTI. Low T3 and high FT4 have been associated with mortality1. Objectives: 1-To evaluate correlation of thyroid hormones with biochemical markers of inflammation and association with disease outcome in hospitalized patients with COVID-19. 2-To evaluate these parameters in the two profiles of NTI. Methods: Prospective single- center study that included 55 consecutively patients with COVID-19 hospitalized from August to November 2020. 28/55 (50 %) were male, median age 56y (21-89). Clinical presentation: asymptomatic 3,6% (n=2), mild 14,3% (n=8), moderate 28,6% (n=16), severe 53,6% (n=30). 74,1% had pneumonia, 3.6% (n=2) died and 79,3% had favorable evolution. Thyroid hormones (T4, T3, FT4, FT3) and their ratios (T3/T4, FT3/FT4) were correlated with inflammatory parameters (albumin, ferritin, fibrinogen, erythrocyte sedimentation rate [ESR], C-reactive protein [CRP], lactate dehydrogenase [LDH], D-dimer). Comparison between hormone levels, clinical presentation and outcome was performed. Statistical analysis: Spearman correlation, Mann Whitney test and Kruskal-Wallis test. Results: We found correlation between thyroid hormones and their ratios with inflammatory parameters (Table). T3/T4 ratio was lower in severe vs mild/moderate disease [7.5 (4.5-15.5) vs 9.2 (5.8-18.1);p=0.04] and in patients who died vs those discharged [5 (4.53-5.6) vs 8.1 (4.7-18.1);p=0.03]. High FT4 NTI had lower albumin [3.4 (3-4) vs 3.7 (3-4);p=0.03], higher ferritin [1202 (930-7127) vs 435 (101-2232);p<0.05] and tendency to higher fibrinogen [681(583-798) vs 508 (307- 807);p=0.06] than normal/low FT4 NTI. No patient with mild disease at onset had high FT4. Image: Conclusion: In this cohort, both thyroid hormones correlated with inflammation parameters and worse clinical outcome. In NTI group with high FT4, inflammatory parameters were more marked and presentation of the disease more severe.