A comparative analysis of the Iris iQ200 with manual microscopy as a diagnostic tool for dysmorphic erythrocytes in urine.

Microscopic analysis of erythrocytes in urine is a valuable diagnostic tool for identifying glomerular hematuria. Indicative of glomerular hematuria is the presence of erythrocyte casts and polyand dysmorphic erythrocytes. In contrast, in non-glomerular hematuria, urine sediment erythrocytes are monoand isomorphic, and erythrocyte casts are absent (1, 2) . To date, various variant forms of dysmorphic erythrocyte morphology have been defi ned and classifi ed. They are categorized as: D1, D2, and D3 cells (2) . D1 and D2 cells are also referred to as acanthocytes or G1 cells which are mickey mouse-like cells with membrane protrusions and severe (D1) to mild (D2) loss of cytoplasmic color (2) . D3 cells are doughnut-like or other polyand dysmorphic forms that include discocytes, knizocytes, anulocytes, stomatocytes, codocytes, and schizocytes (2, 3) . The cellular morphology of these cells is observed to have mild cytoplasmic loss, and symmetrical shaped membranes free of protrusions. Echinocytes and pseudo-acanthocytes (bite-cells) are not considered to be dysmorphic erythrocytes. Glomerular hematuria is likely if more than 40 % of erythrocytes are dysmorphic or 5 % are D1-D2 cells and nephrologic work-up should be considered (2) . For over 20 years, manual microscopy has been the prevailing technique for examining dysmorphic erythrocytes in urine sediments when glomerular pathology is suspected (4, 5) . This labor-intensive method requires signifi cant expertise and experience to ensure consistent and accurate analysis. A more immediate and defi nitive automated technique that classifi es dysmorphic erythrocytes at least as good as the manual method would be an invaluable asset in the routine clinical laboratory practice. Therefore, the aim of the study was to investigate the use of the Iris Diagnostics automated iQ200 (Instrumentation Laboratory, Brussels, Belgium) as an automated platform for screening of dysmorphic erythrocytes. The iQ200 has proven to be an effi cient and reliable asset for our urinalysis (5) , but has not been used for the quantifi cation of dysmorphic erythrocytes. In total, 207 urine specimens of patients with suspected glomerular pathology were initially examined using manual phase contrast microscopy by two independent experienced laboratory technicians at a university medical center. The same specimens were re-evaluated using the Iris iQ200 instrument at our facility, which is a teaching hospital. The accuracy of the iQ200 was compared to the results of manual microscopy for detecting dysmorphic erythrocytes. Urine samples were processed within 2 h of voiding. Upon receipt, uncentrifuged urine samples were used for strip analysis using the AutionMax Urine Analyzer (Menarini, Valkenswaard, The Netherlands). For analysis of dysmorphic erythrocytes 20 mL urine was fi xed with CellFIX TM (a formaldehyde containing fi xative solution; BD Biosciences, Breda, The Netherlands) at a dilution of 100:1 (6) . One half of fi xed urine was centrifuged at 500 × g for 10 min and the pellet analyzed by two independent experienced technicians using phase-contrast microscopy. The other half was analyzed by automated urine sediment analyzer using the iQ200. The iQ200 uses a fl ow cell that hydrodynamically orients the particles within the focal plane of a microscopic lens coupled to a 1.3 megapixel CCD digital camera. Each particle image is digitized and sent to the instrument processor. For our study, the instrument ’ s cellrecognition function for classifying erythrocytes was used. Although the iQ200 can easily recognize and classify normal erythrocytes it cannot automatically classify dysmorphic erythrocytes. Instead, two independent and experienced technicians review the images in categories ‘ normal erythrocytes ’ and ‘ unclassifi ed ’ and reclassify dysmorphic erythrocytes to a separate ‘ dysmorphic ’ category. To minimize *Corresponding author: Ayşe Y. Demir, MD, PhD, Department of Clinical Chemistry and Haematology, Meander Medical Center Utrechtseweg 160, 3818 ES Amersfoort, The Netherlands Phone: + 31 33 8504344, Fax: + 31 33 8502035 , E-mail: ay.demir@meandermc.nl Received September 20, 2011; accepted November 15, 2011; previously published online December 7, 2011