Background Gastrointestinal manifestations of coronavirus disease 2019 (COVID-19) appear to be substantial. Fecal calprotectin is a promising biomarker in COVID-19 associated gastrointestinal inflammation; however, its role in the severity of COVID-19 remains limited. We conducted a study to analyze the relationship between the severity of COVID-19 and hypoxic intestinal damage. Methods We assessed the severity of 44 hospitalized COVID-19 pneumonia patients based on the PaO2/FiO2 (P/F) ratio. Inflammatory markers were measured from blood samples, and fecal calprotectin was obtained from stool samples. Results Median levels of fecal calprotectin in COVID-19 patients involved in this study (n = 44) were found to be markedly elevated along with the severity of hypoxemia, as seen in the non-acute respiratory distress syndrome (ARDS) group 21.4 µg/g (5.2–120.9), mild ARDS 54.30 µg/g (5.2–1393.7), moderate ARDS 169.6 µg/g (43.4–640.5), and severe ARDS 451.6 µg/g (364.5–538.6). We also found significant differences in fecal calprotectin levels based on the severity of ARDS (P < 0.001), and although the patients were divided into ARDS and non-ARDS groups (P < 0.001). Furthermore, we found a strong negative correlation between the P/F ratio and fecal calprotectin levels (r = − 0.697, P < 0.001). Conclusion Our findings support the potential role of fecal calprotectin as a biomarker of intestinal inflammation in COVID-19 as a consequence of hypoxic intestinal damage and as suggested by the reduced P/F ratio.

Background: ACE-2 receptors are well-known as binding receptors to spike protein of SARS-CoV-2 highly expressed in the gastrointestinal system. The Role of SARS-CoV-2 viral load and its effect on gut inflammation in COVID-19 patients are still not well-understood. This study aims to determine the impact of SARS-CoV-2 viral load on gastrointestinal inflammation. Methods: A total of 44 inpatient subjects who fulfilled eligibility criteria were examined for cycle threshold values from nasopharyngeal swab samples collected from several nucleic levels based on fluorescence signal and calprotectin levels of stool samples using Calprotectin enzyme-linked immunosorbent assay (ELISA) kit. Results: Of 44 subjects, 52.3% were male, with a median age of 52.5 years. Hypertension or diabetes was found in 26 patients. The median cycle threshold value was 31.3 with a value range of 10.9-40.0, median cycle threshold was significantly lower in subjects with comorbidity with P = 0.01. The median fecal calprotectin level was 42 μg/g with a value range of 5.1-1,393.7 μg/g, with median fecal calprotectin significantly higher in subjects with gastrointestinal symptoms with P = 0.008 with a relative risk (RR) of 5.5. There was a significant correlation between cycle threshold and fecal calprotectin in subjects with comorbidity with P <0.05, a coefficient contingency of 0.414. Conclusion: Subjects with comorbidity are prone to have higher viral loads paralleled with gastrointestinal inflammation. Subjects with overt gastrointestinal manifestations had a five-fold higher degree of gut inflammation.