Manual urine microscopy versus automated urine analyzer microscopy in patients with acute kidney injury.

OBJECTIVE: To examine whether a significant difference exists between the reported ranges of granular and muddy brown casts in urine specimens using manual microscopy compared with an automated urine analyzer in a cohort of patients with acute kidney injury (AKI).

METHODS: Freshly voided urine specimens from 25 consecutive patients who were under evaluation by the Department of Nephrology for AKI were simultaneously examined using the iQ200 automated microscopy system and manual microscopy performed by a trained observer. We coded the results according to the number of pathological casts identified and performed a 3 × 2 Freeman-Halton extension of the Fisher exact probability test.

RESULTS: Overall, the number of casts identified via manual microscopy differed significantly (P <.001) from the number identified via the automated microscopy system.

CONCLUSIONS: This study provides evidence of the importance of performing a manual microscopic examination of urine sediment in patients with AKI. Further studies are needed to assess whether manual microscopy provides prognostic implications regarding renal recovery, hemodialysis dependency, and mortality.