CRP and infection: In addition, they recommend that thresholds to define ID in individuals with infection or inflammation should be raised to 30 mg/L for children under 5 and 70 mg/L serum ferritin for all age groups over 5.44 However, very few studies (n=4 out of 23 studies that used ferritin with or without other biomarkers to define ID) measured and excluded participants with elevated CRP level.46 104 105 107 Only one study measured AGP108 and only two studies from Colombia85 and Brazil109 used the higher thresholds for ferritin to define ID in the context of inflammation.