Flow cytometry of urinary erythrocytes for evaluating the source of haematuria.

Morphological examinations of urinary erythrocytes can be of diagnostic help in the initial evaluation of haematuria. Dysmorphic red blood cells are known to indicate a glomerular origin of bleeding. Automated flow cytometry produces objective measurements, but is hampered by disturbing signals from urinary debris. The present study is based on both volumetry and densiometry of red blood cells by the Technicon H-1TM system. Urines from 63 patients with both low grade and macroscopic haematuria were examined. The test sensitivity for detecting a non-glomerular source of bleeding was 0.75 (specificity: 0.86). After excluding 20 samples with either a low red cell count or a density below 1005, the sensitivity rose to 0.93 with a corresponding specificity of 1.00. The present findings suggest that partial reinterpretation of the autoanalyser data will enhance the diagnostic power of flow cytometry. This method could be made suitable for routine clinical use.