Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 14 6 2022 12 06 913 920 Nagehan Sari Department of Clinical Microbiology and Infectious Diseases, Istanbul Training and Research Hospital, University of Health Sciences, Istanbul, Turkey Istemi Serin Department of Hematology, Istanbul Training and Research Hospital, University of Health Sciences, Istanbul, Turkey Ayfer Bakir Department of Medical Microbiology, Gulhane Training and Research Hospital, University of Health Sciences, Istanbul, Turkey Sema Alacam Department of Medical Microbiology, Istanbul Training and Research Hospital, University of Health Sciences, Istanbul, Turkey 2021 04 04 2022 09 11 Background and Objectives: Neutrophil / lymphocyte (NLR) and thrombocyte / lymphocyte ratios (TLR) are also a guiding factors in the prognostic evaluation of infectious diseases. Another parameter to determine inflammation and prognosis is albumin. This study was aimed to determine whether TLR, NLR and neutrophil / albumin ratios (NAR) are effective in predicting the severity and course of Corona Virus Disease-2019 (COVID-19). Materials and Methods: In this retrospective and cross-sectional study, a total of 1597 patients who were admitted to our hospital between 15.03.2020- 1.06.2020, diagnosed with COVID-19 were evaluated. Results: In the estimation of the decision for hospitalization, TLR, NLR and NAR AUROC values were 0.596, 0.634, 0.602 for cutoff values 123.7, 2.3 and 839.5, respectively. In predicting mortality, TLR, NLR and NAR AURO sample size can be specified C values were 0.674, 0.821, 0.787 for cutoff values 168.1, 5.2 and 1303.4, respectively (p <0.001 for all). Conclusion: In our study, it was determined that TLR, NLR and NAR are independent predictors in making the decision of hospitalization and in determining the prognosis in patients who are decided to be hospitalized. https://ijm.tums.ac.ir/index.php/ijm/article/view/3075 https://ijm.tums.ac.ir/index.php/ijm/article/download/3075/1532