Screening for iron deficiency in surgical patients based on noninvasive zinc protoporphyrin measurements

Abstract

BACKGROUNDApproximately every third surgical patient is anemic. The most common form, iron deficiency anemia, results from persisting iron‐deficient erythropoiesis (IDE). Zinc protoporphyrin (ZnPP) is a promising parameter for diagnosing IDE, hitherto requiring blood drawing and laboratory workup.STUDY DESIGN AND METHODSNoninvasive ZnPP (ZnPP‐NI) measurements are compared to ZnPP reference determination of the ZnPP/heme ratio by high‐performance liquid chromatography (ZnPP‐HPLC) and the analytical performance in detecting IDE is evaluated against traditional iron status parameters (ferritin, transferrin saturation [TSAT], soluble transferrin receptor–ferritin index [sTfR‐F], soluble transferrin receptor [sTfR]), likewise measured in blood. The study was conducted at the University Hospitals of Frankfurt and Zurich.RESULTSLimits of agreement between ZnPP‐NI and ZnPP‐HPLC measurements for 584 cardiac and noncardiac surgical patients equaled 19.7 μmol/mol heme (95% confidence interval, 18.0–21.3; acceptance criteria, 23.2 μmol/mol heme; absolute bias, 0 μmol/mol heme). Analytical performance for detecting IDE (inferred from area under the curve receiver operating characteristics) of parameters measured in blood was: ZnPP‐HPLC (0.95), sTfR (0.92), sTfR‐F (0.89), TSAT (0.87), and ferritin (0.67). Noninvasively measured ZnPP‐NI yielded results of 0.90.CONCLUSIONZnPP‐NI appears well suited for an initial IDE screening, informing on the state of erythropoiesis at the point of care without blood drawing and laboratory analysis. Comparison with a multiparameter IDE test revealed that ZnPP‐NI values of 40 μmol/mol heme or less allows exclusion of IDE, whereas for 65 μmol/mol heme or greater, IDE is very likely if other causes of increased values are excluded. In these cases (77% of our patients) ZnPP‐NI may suffice for a diagnosis, while values in between require analyses of additional iron status parameters.

Spectroscopic methods to quantify molecules of the heme‐biosynthesis pathway: A review of laboratory work and point‐of‐care approaches

“…In the third study on 584 surgical patients, most of which had concomitant inflammation, the noninvasive ZnPP measurement was compared with other iron status markers (eg, ferritin, transferrin saturation, soluble transferrin receptor), and it could be shown that ZnPP was the best single marker to identify patients with iron deficiency erythropoiesis [67].…”

“…The accuracy and applicability of the noninvasive ZnPP measurement have been investigated in three clinical studies on women postpartum, infants and children and on elderly surgical patients [46, 66, 67].…”

Outcome-relevante Anästhesiologie: peri- und postoperative Anämiebehandlung

“…Neben der Anämiediagnostik kann der Ret-Hb, ebenso wie das Hepcidin, auch zum Therapiemonitoring während einer Eisensubstitution genutzt werden 21 . Auch nichtinvasive Methoden zur Detektion eines Eisenmangels sind Gegenstand aktueller Forschung, wie die Messung des Zinkprotoporphyrins (ZnPP) 22 .…”

Iron deficiency and biomarkers of inflammation: a 3-year prospective analysis of the DO-HEALTH trial

“…We used soluble transferrin receptor levels (sTfR) levels as a clinical marker of ID at baseline and over the follow-up, since this parameter is not influenced by inflammation. [24] The threshold of more than 28.1 nmol/L was used to define ID as it was validated in older adults. [25][26][27] sTfR levels were measured with Tina-quant Transferrin ver.2 Test on a cobas c 502 analyser (Roche) using an Immunoturbidimetric assay.…”