Is Erythrocyte Protoporphyrin a Better Single Screening Test for Iron Deficiency Compared to Hemoglobin or Mean Cell Volume in Children and Women?

Abstract

Hemoglobin (Hb), mean cell volume (MCV), and erythrocyte protoporphyrin (EP) are commonly used to screen for iron deficiency (ID), but systematic evaluation of the sensitivity and specificity of these tests is limited. The objective of this study is to determine the sensitivity and specificity of Hb, MCV, and EP measurements in screening for ID in preschool children, non-pregnant women 15–49 years of age, and pregnant women. Data from the National Health and Nutrition Examination Surveys (NHANES) (NHANES 2003–2006: n = 861, children three to five years of age; n = 3112, non-pregnant women 15 to 49 years of age. NHANES 1999–2006: n = 1150, pregnant women) were examined for this purpose. Children or women with blood lead ≥10 µg/dL or C-reactive protein (CRP) >5.0 mg/L were excluded. ID was defined as total body iron stores <0 mg/kg body weight, calculated from the ratio of soluble transferrin receptor (sTfR) to serum ferritin (SF). The receiver operating characteristic (ROC) curve was used to characterize the sensitivity and specificity of Hb, MCV, and EP measurements in screening for ID. In detecting ID in children three to five years of age, EP (Area under the Curve (AUC) 0.80) was superior to Hb (AUC 0.62) (p < 0.01) but not statistically different from MCV (AUC 0.73). In women, EP and Hb were comparable (non-pregnant AUC 0.86 and 0.84, respectively; pregnant 0.77 and 0.74, respectively), and both were better than MCV (non-pregnant AUC 0.80; pregnant 0.70) (p < 0.01). We concluded that the sensitivity and specificity of EP in screening for ID were consistently superior to or at least as effective as those of Hb and MCV in each population examined. For children three to five years of age, EP screening for ID was significantly better than Hb and similar to MCV. For both non-pregnant and pregnant women, the performance of EP and Hb were comparable; both were significantly superior to MCV.

The Importance of Iron Status for Young Children in Low- and Middle-Income Countries: A Narrative Review

“…Of note, paper-based smartphone-app-guided point-of-care assays for ferritin and sTfR show promise in proof-of-principle studies, suggesting field measurement of these markers in children from resource-limited settings may become feasible [97,98]. Other markers of iron-restricted erythropoiesis are zinc protoporphyrin (ZPP) and the ZPP/haem ratio in red blood cells; ZPP accumulates in the last step of haemoglobin synthesis when iron is lacking [99]. Certain red cell indices may also be useful as markers of iron deficient erythropoiesis [24], among which reticulocyte haemoglobin content (Ret-Hb/CHr) is prominent [100,101] and included in the American Academy of Pediatrics guidelines for the evaluation of anaemia [24].…”

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

“…While analysis of iron supply in the bone marrow with Perls’ Prussian blue staining is the “gold standard” for the diagnosis of ID [ 29 ], this technique is costly, highly invasive and nonautomated, and is therefore not practicable in patients with IBD in routine practice. Since the use of a single iron status parameter could result in over- or underdiagnosis of IRE, a multiparameter index test was performed [ 30 , 31 ]. Patients were assigned to the “IRE group” if at least two of three parameters (TSAT, SF, ZnPP) indicated IRE, or the “no IRE group” if a maximum of one parameter was positive [ 22 ].…”

Intravenöse Eisensubstitution bei chronischer Erkrankung – bei wem, wann und wie?

“…Ein isolierter Serumeisenwert ist ungenügend verwertbar. Mikrozytäre, hypochrome Erythrozyten können im Blutbild Hinweise auf einen Eisenmangel geben, wobei die Auswertung von 3104 nichtschwangeren Frauen im Rahmen der amerikanischen NHANES-Untersuchung in den Jahren 1999 -2006 bei einer angesetzten Spezifität von 80 % eine Sensitivität von nur 61 % des mittleren zellulären Volumens (MCV) ergab [14]. Die vorrangigen Eisenparameter im Alltag sind Serumferritin und Transferritinsättigung (TSAT).…”