CRP and COVID-19: However, symptomatic COVID-19 patients had significantly higher iron concentration and lower CRP level in comparison to those without GI problems (22.9 (21.3–23.4) vs. 16.1 (11.7–19.7) μmol/L; p < 0.001 and 1.2 (0.77–6.61) vs. 5.6 (2.2–21.3) mg/L; p = 0.03; respectively).