HR/SIM analysis of HGFL peptide in human urine. (A)The ion peaks of HGFL peptide m/z 585.79 and internal standard (IS) m/z 590.80 were chosen for the high resolution/selective ion monitoring (HR/SIM) analysis using LTQ Orbitrap XL™ mass spectrometer. Extracted ion chromatograms (EICs) were based on a ±0.01 Da mass extraction window (MEW) centered on the theoretical m/z. (B) SCD patients at risk for developing renal disease based on the presence of hemoglobinuria showed significantly increased HGFL levels (1.72-fold, p=0.015).