[Development of a new method for diagnosing the origin of urinary bleeding by doghnut-shape urinary red blood cells]

Although the presence of acanthocytes (AC) is a reliable indicator of glomerular bleeding, acanthocytes could be observed in only 60% of patients with glomerulonephritis. Therefore, we attempted to develop a new method for diagnosing the origin of urinary bleeding by the morphological characteristics of doughnut-shaped of urinary red blood cells (RBC). In the present study, urine samples from 7 patients with glomerular bleeding and 4 patients with non-glomerular bleeding, and from 35 urine samples of the glomerular bleeding and non-glomerular bleeding-model were examined. The various type of RBC were observed by a phase contrast microscopic examination. The doughnut-shaped RBC were divided into three shapes (namely, smooth, uneven, target-shaped RBC) by individual characteristics. The appearance rate of each shape was calculated, and both outer and inner diameters of doughnut-shaped RBC in the photographs were also measured. Although there was no change in the value of outer diameter of doughnut-shaped RBC between glomerular bleeding and non-glomerular bleeding, the values of inner diameter of doughnut-shaped RBC in non-glomerular bleeding was significantly smaller than those in glomerular bleeding in all shapes. These results strongly suggested that the measurement of inner diameters of doughnut-shaped RBC is one of the useful diagnostic methods to distinguish the origin of urinary bleeding when AC could not be observed.