Diagnostic value of white blood cell parameters for COVID-19: Is there a role for HFLC and IG?

Introduction As the Coronavirus disease 2019 (COVID-19) pandemic is still ongoing with patients overwhelming healthcare facilities, we aimed to investigate the ability of white blood cell count (WBC) and their subsets, high fluorescence lymphocyte cells (HFLC), immature granulocyte count (IG), and C-reactive protein (CRP) to aid diagnosis of COVID-19 during the triage process and as indicators of disease progression to serious and critical condition. Methods We collected clinical and laboratory data of patients, suspected COVID-19 cases, admitted at the emergency department of University General Hospital of Ioannina (Ioannina, Greece). We selected 197 negative and 368 positive cases, confirmed by polymerase chain reaction test for severe acute respiratory syndrome coronavirus 2. COVID-19 cases were classified into mild, serious, and critical disease. Receiver operating characteristic curve and binary logistic regression analysis were utilized for assessing the diagnosing ability of biomarkers. Results WBC, neutrophil count (NEUT), and HFLC can discriminate efficiently negative cases from mild and serious COVID-19, whereas eosinopenia and basopenia are early indicators of the disease. The combined WBC-HFLC marker is the best diagnostic marker for both mild (sensitivity: 90.6% and specificity: 64.1%) and serious (sensitivity: 90.3% and specificity: 73.4%) disease. CRP and Lymphocyte count are early indicators of progression to serious disease whereas WBC, NEUT, IG, and neutrophil-to-lymphocyte ratio are the best indicators of critical disease. Conclusion Lymphopenia is not useful in screening patients with COVID-19. HFLC is a good diagnostic marker for mild and serious disease either as a single marker or combined with WBC whereas IG is a good indicator of progression to critical disease.