Objective: The objective of the study is to describe the clinical and laboratory characteristics of critically ill coronavirus disease-2019 (COVID-19) patients treated with dexamethasone in an intensive care unit (ICU) to provide a support tool for clinical decision-making. Design: A survey was conducted among hospitalized patients from November 2020 to March 2021, with data collected through patient interviews, medical records, and laboratory tests. Setting: This is a large hospital serving as a reference center for COVID-19 care in Bahia, Brazil. Patients: A convenience sample of 22 patients admitted to the COVID-19 ICU who signed informed consent to participate in the study. Methods: A cross-sectional study of patients admitted to the ICU with COVID-19. Data were analyzed using statistical methods. Results: The most common comorbidities among patients were hypertension (54%), diabetes (36%), and cardiovascular disease (27%). Among the deaths recorded, 55% of patients had hypertension, 44% had diabetes and/or required insulin therapy, 33% had a history of cardiovascular disease (including atrial fibrillation and congestive heart failure), and 22% had a history of stroke. Renal dysfunction (elevated creatinine); liver function abnormalities (increased alanine aminotransferase and aspartate aminotransferase); and elevated levels of ferritin, fibrinogen, and D-dimer were identified as potential indicators of disease progression. Among these factors, only elevated creatinine demonstrated a statistically significant association with an increased mortality risk. Conclusion: These findings provide a better understanding of the clinical course of severe acute respiratory syndrome coronavirus 2 infections and suggest that laboratory medicine is crucial in supporting clinical decision-making and advancing scientific and healthcare knowledge during the early phases of the COVID-19 pandemic. Relevance for patients: Identifying key risk factors, such as renal dysfunction, can improve early intervention and personalized treatment for critically ill COVID-19 patients.