Diagnostic value of urine erythrocyte morphology in the detection of glomerular disease in SurePath™ liquid-based cytology compared with fresh urine sediment examination.

OBJECTIVE

To assess whether the morphology of urine erythrocytes can be an effective tool for distinguishing glomerular disease from lower urinary tract disease in SurePath™ liquid-based cytology (SP-LBC).

METHODS

We examined four morphological parameters of erythrocytes: (1) irregular erythrocytes (of all types including fragmented forms) comprising greater than or equal to 20% of erythrocytes; (2) uniform erythrocytes (>80%); (3) doughnut or target-like shaped (D/T) erythrocytes (≥1%); and (4) acanthocytes (≥1%) in glomerular disease (n = 32) and lower urinary tract disease (n = 20) with SP-LBC slides in cases that had also been assessed by fresh urine sediment examination.

RESULTS

Sensitivity of D/T erythrocytes and acanthocytes (dysmorphic erythrocytes) for glomerular disease were 100% and 87.5%, respectively, with urine sediment examination, and 81.3% and 46.9%, respectively, in SP-LBC slides. Specificity was 100% for D/T erythrocytes and acanthocytes using either procedure. While irregular erythrocytes were specific for glomerular disease using urine sediment examination, they were seen in 70% of those with lower urinary tract disease using SP-LBC slides as a result of the deformation of erythrocytes by the fixative.

CONCLUSIONS

Although the sensitivity of D/T erythrocytes and acanthocytes for glomerular disease was lower in SP-LBC slides than fresh urine sediment examination, their specificity was equally high. Therefore, urine erythrocyte morphology is useful in the detection of glomerular disease with the SP-LBC slides. However, morphological features apart from D/T erythrocytes and acanthocytes are not useful in SP-LBC slides.