Zinc Protoporphyrin Is a Reliable Marker of Functional Iron Deficiency in Patients with Inflammatory Bowel Disease

Abstract

Iron deficiency (ID) is a common manifestation of inflammatory bowel disease (IBD), arising primarily due to chronic inflammation and/or blood loss. There is no gold standard for ID diagnosis, which is often complicated by concomitant inflammation. Zinc protoporphyrin (ZnPP) correlates with parameters of iron homeostasis and has been identified as a promising marker for ID, irrespective of inflammation. We investigated the diagnostic performance of ZnPP in ID, iron deficiency anemia, anemia of chronic disease and mixed anemia in a cross-sectional study in 130 patients with IBD. Different parameters were compared by receiver operator characteristic (ROC) analysis as detectors of iron-restricted erythropoiesis (IRE). IRE was detected in 91 patients (70.0%); fifty-nine (64.8%) had absolute ID and 23 (25.4%) functional ID. When inflammation was present, ZnPP was a more reliable sole biomarker of IRE than MCV, transferrin saturation (TSAT) or ferritin (AUC; 0.855 vs. 0.763, 0.834% and 0.772, respectively). The specificity of TSAT was significantly lower than ZnPP when inflammation was present (38% vs. 71%, respectively). We conclude that ZnPP is a reliable biomarker of functional ID in patients with IBD and more dependable than ferritin or TSAT, which are influenced by chronic inflammation. We propose that ZnPP may also have utility in patients with other chronic diseases.

Zinc protoporphyrin levels in COVID-19 are indicative of iron deficiency and potential predictor of disease severity

“…Different studies have identified ZnPP as a biomarker of IDA which is not or little affected by co-occurring acute inflammations [ 14 , 40 ]. In ACD ZnPP has been shown to detect and quantify derangements of iron metabolism associated with chronic inflammatory disorders and also helps to monitor the success of iron therapy of chronic inflammatory diseases[ 23 , 41 ].…”

“…Many of the biomarkers are not only affected by iron deficiency but also by inflammation; such as ferritin, a well-known acute-phase protein[ 11 – 13 ]. However, it has been shown that ZnPP is less sensitive to the inflammatory status [ 14 ]. In COVID-19 patients some of the iron markers are affected [ 6 , 15 ].…”

“…Based on recent publications, however, there are indications of possible specific interlinks between blood pathologies and COVID-19 suggesting a strong involvement of erythrocytes in the pathophysiology of COVID-19. We addressed the question to which extend the classical biomarkers such as ferritin, soluble transferrin receptor, total iron-binding capacity, transferrin saturation, hepcidin, and serum iron can be used for the diagnosis of iron deficiency anemia, but also ZnPP which is a less frequently used biomarker that, however, is less affected by the severity of inflammation compared to the others [ 14 ].…”