title: A rapid paper-based test for quantifying sickle hemoglobin in blood samples from patients with sickle cell disease.
abstract: Quantification of sickle hemoglobin (HbS) in patients with sickle cell disease (SCD) undergoing hydroxyurea or chronic transfusion therapy is essential to monitoring the effectiveness of these therapies. The clinical monitoring of %HbS using conventional laboratory methods is limited by high per-test costs and long turnaround times usually associated with these methods. Here we demonstrate a simple, rapid, inexpensive paper-based assay capable of quantifying %HbS in blood samples from patients with SCD. A 20 μL droplet of whole blood and hemoglobin solubility buffer was deposited on chromatography paper. The relative color intensities of regions of the resulting blood stain, determined by automated image analysis, are used to estimate %HbS. We compared the paper-based assay with hemoglobin electrophoresis (comparison method) using blood samples from 88 subjects. The test shows high correlation (R(2)  = 0.86) and strong agreement (standard deviation of difference = 7%HbS) with conventional Hb electrophoresis measurement of %HbS, and closely approximates clinically predicted change in %HbS with transfusion therapy (mean difference 2.6%HbS, n = 5). The paper-based assay can be completed in less than 35 min and has a per-test cost less than $0.25. The assay is accurate across a wide range of HbS levels (10-97%) and hemoglobin concentrations (5.6-12.9 g/dL) and is unaffected by high levels of HbF (up to 80.6%). This study demonstrates the feasibility of the paper-based %HbS assay. The paper-based test could improve clinical care for SCD, particularly in resource-limited settings, by enabling more rapid and less expensive %HbS monitoring.
authors.affiliation: Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, Texas.
authors.forename: Nathaniel Z
authors.initials: NZ
authors.lastname: Piety
authors.affiliation: Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, Texas.
authors.forename: Xiaoxi
authors.initials: X
authors.lastname: Yang
authors.affiliation: Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, Texas.
authors.forename: Dalia
authors.initials: D
authors.lastname: Lezzar
authors.affiliation: Section of Hematology-Oncology, Department of Pediatrics, Baylor College of Medicine, Houston, Texas.
authors.forename: Alex
authors.initials: A
authors.lastname: George
authors.affiliation: Department of Biomedical Engineering, Cullen College of Engineering, University of Houston, Houston, Texas.
authors.forename: Sergey S
authors.initials: SS
authors.lastname: Shevkoplyas
mesh_terms: D000755:Anemia, Sickle Cell / Q000097:blood*; D005260:Female; D006403:Hematologic Tests / Q000295:instrumentation* / Q000379:methods*; D006451:Hemoglobin, Sickle / Q000378:metabolism*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D010209:Paper; D012680:Sensitivity and Specificity
chemical_list: D006451:Hemoglobin, Sickle