2000 Volume 13 Issue 1 Pages 39-42
Background
Hematuria is an important finding, because it can be a clue to the diagnosis of glomerular or urological disorders. Quantitative evaluation of hematuria is usually assessed by the number of red blood cells (rbc) under light microscopy (LM), using a centifuged urine sediment. It is, however, postulated that the number of rbc under LM is inaccurate in certain conditions.
Purpose
This study was undertaken to investigate the condition which affects the number of rbc in a centrifuged urine sediment using the LM, and to compare it with the results obtained by a newly developed automated urinary flow cytometer, the UF-100 (Toa Medical Electronics Co., Ltd, Kobe, Japan).
Method & Results
1. Considerable amounts of rbc remained in the supernatant of urine even after routine centrifugation (500g, 5min.). 2. The number of rbc in sediment is affected by the specific gravity of urine, i. e., it was significantly lower in diluted urine than in concentrated urine. 3. Results obtained by the LM correlated well with those by the UF-100. However in several samples, the UF-100 detected the hematuria which was overlooked by the LM.
Conclusion
The number of rbc in a centrifuged urine sediment evaluated by the LM fluctuates considerably by the condition of urine, while an automated urinary flow cytometer, the UF-100 demonstrates rather good reproducibility. From these findings, we suggest that the condition of urine, such as specific gravity, should be taken into consideration when we evaluate the quantity of hematuria analyzed by the LM using centifuged urine samples. In this regard, quantitative analysis by the UF-100 is highly recommended for its good reproducibility.
