Non-invasive Diagnostics of Iron Deficiency in Surgical Patients by Measuring Zinc Protoporphyrin-IX

* In approx. 40% of the incidences anemia is caused by iron deficiency (= ID). In turn, preoperative iron-deficiency anemia (= IDA) is associated with an increase in morbidity and mortality as well as with the need for a blood transfusion. * A successful preoperative treatment of IDA via iron supplementation requires a timely screening of iron deficiency, typically done by analyzing specific blood parameters. This however of course requires drawing a blood sample which further reduces the patients' blood volume and is in many cases stated as an inconvenient procedure. * Measured in blood zinc protoporphyrin-IX (= ZnPP) is an established parameter to detect ID. * This study aims to evaluate a prototype device detecting ZnPP non-invasively in the intact oral mucosa of surgical patients. * Results from the non-invasive measurement will be compared to reference measurements of ZnPP from residual blood samples (HPLC analysis) as well as to other parameters including Hb level and iron profile (MCH \[= mean corpuscular hemoglobin\], MCV \[= mean corpuscular volume\], ferritin, transferrin, transferrin saturation, soluble transferrin receptor, CRP).