title: Dual-wavelength excitation for fluorescence-based quantification of zinc protoporphyrin IX and protoporphyrin IX in whole blood.
abstract: Quantification of erythrocyte zinc protoporphyrin IX (ZnPP) and protoporphyrin IX (PPIX), individually or jointly, is useful for the diagnostic evaluation of iron deficiency, iron-restricted erythropoiesis, lead exposure, and porphyrias. A method for simultaneous quantification of ZnPP and PPIX in unwashed blood samples is described, using dual-wavelength excitation to effectively eliminate background fluorescence from other blood constituents. In blood samples from 35 subjects, the results of the dual-wavelength excitation method and a reference high performance liquid chromatography (HPLC) assay were closely correlated both for ZnPP (rs = 0.943, p < 0.0001; range 37-689 μmol ZnPP/mol heme, 84-1238 nmol/L) and for PPIX (rs = 0.959, p < 0.0001; range 42-4212 μmol PPIX/mol heme, 93-5394 nmol/L). In addition, for ZnPP, the proposed method is compared with conventional single-wavelength excitation and with commercial front-face fluorimetry of washed erythrocytes and whole blood. We hypothesize that dual-wavelength excitation fluorimetry will provide a new approach to the suppression of background fluorescence in blood and tissue measurements of ZnPP and PPIX.
authors: Laser-Forschungslabor, LIFE Center, Klinikum der Universität München, Marchioninistr. 23, 81377 München, Germany. georg.hennig@med.lmu.de.
authors: Georg
authors: G
authors: Hennig
authors: Christian
authors: C
authors: Gruber
authors: Michael
authors: M
authors: Vogeser
authors: Herbert
authors: H
authors: Stepp
authors: Stephan
authors: S
authors: Dittmar
authors: Ronald
authors: R
authors: Sroka
authors: Gary M
authors: GM
authors: Brittenham
mesh_terms: D000465:Algorithms; D018798:Anemia, Iron-Deficiency / Q000097:blood* / Q000175:diagnosis; D015415:Biomarkers / Q000097:blood; D006801:Humans; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D057054:Molecular Imaging / Q000379:methods*; D011524:Protoporphyrins / Q000097:blood*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*
chemical_list: D015415:Biomarkers; D011524:Protoporphyrins; C017803:zinc protoporphyrin; C028025:protoporphyrin IX
keywords: blood; fluorescence; protoporphyrin IX; spectrum analysis; zinc protoporphyrin