Abstract

Introduction Given the many misconceptions in terms of both diagnosis and treatment, SARS-CoV-2 continues to infect and victimize. Notwithstanding molecular testing is the gold standard method of in vitro diagnostic, the often long-waiting time, as well as false-negative results are daunting challenges facing us. In this study, we aimed to report the diagnostic value of laboratory findings in COVID-19 patients, with an extensive focus on the differences between PCR-positive and PCR-negative cases. Patients and methods We did a retrospective single-centre study on a large cohort of 1546 COVID-19 patients in Tehran, Iran. Based on clinical symptoms, chest CTs were performed for all the patients. Also, molecular testing of swab specimens was also performed for 1450 cases. Results All the data on laboratory results were retrospectively extracted from medical records. Of the 1546 patients, 1040 (67.5) were male and 506 (32.5) were female with the mean age of 55.67. On admission, 31.4 of the whole study population displayed lymphopenia and 38.9 showed neutrophilia. Decreased hemoglobin and mild thrombocytopenia were also found in 40 and 18.6 of cases, respectively. Elevated lactate dehydrogenase in nearly 75 of COVID-19 cases was the most common alteration amongst biochemical parameters which together with increased ESR and CRP could serve as diagnostic markers in SARS-CoV-2 infection. Of the 1450 patients with a PCR result, 439 (28.3) were PCR-negative and 1011 (65.3) were PCR-positive. Notably, lymphopenia and increased AST were higher in the PCR-positive group than their negative counterparts. Albeit being in the normal range, a significant decrease in the number of monocytes was also evident in the PCR-positive cases. Conclusions As far we are aware, this is the first time that we reported a comprehensive exploration of laboratory characteristics of a large cohort of hospitalized COVID-19 patients from Iran, hoping that these data will cast more light on the diagnostic significance of these parameters.