Urine microscopy is associated with severity and worsening of acute kidney injury in hospitalized patients.
OBJECTIVE
Serum creatinine concentration at the time of nephrology consultation is not necessarily indicative of the severity of acute kidney injury (AKI). Although urine microscopy is useful to differentiate AKI, its role in predicting adverse clinical outcomes has not been well described.


METHODS
The relationship between urine microscopy findings at the time of nephrology consultation for AKI and clinical outcomes was evaluated prospectively. A urinary sediment scoring system was created on the basis of the number of renal tubular epithelial cells and granular casts. The primary outcome was worsening of AKI (progressing to higher AKI Network stage, dialysis, or death) during hospitalization.


RESULTS
Of 249 patients consulted for AKI, 197 had acute tubular necrosis or prerenal AKI and were included in the analysis. At consultation, 80 (40%) had stage 1, 53 (27%) had stage 2, and 66 (33%) had stage 3 AKI. The urinary sediment combined scores were lowest in those with stage 1 and highest in stage 3 AKI. Seventy-nine patients (40%) experienced worsening of AKI from the time of consultation. The urinary scoring system was significantly associated with increased risk of worsening AKI (adjusted relative risk: 7.3; 95% confidence interval: 4.5 to 9.7 for worsening with score of > or =3 versus score of 0) and was more predictive than AKI Network stage at the time of consultation.


CONCLUSIONS
The urinary sediment score may be a useful tool to predict worsening of AKI due to either acute tubular necrosis or prerenal AKI during hospitalization.
Perazella
Mark A
MA
Section of Nephrology, Yale University, New Haven, CT 06520-8029, USA. Mark.perazella@yale.edu
Coca
Steven G
SG
Hall
Isaac E
IE
Iyanam
Umo
U
Koraishy
Madiha
M
Parikh
Chirag R
CR
D000368:Aged; D004847:Epithelial Cells / Q000473:pathology*; D005260:Female; D006760:Hospitalization; D006801:Humans; D007297:Inpatients; D007674:Kidney Diseases / Q000175:diagnosis* / Q000401:mortality / Q000473:pathology / Q000652:urine; D007683:Kidney Tubular Necrosis, Acute / Q000175:diagnosis* / Q000401:mortality / Q000473:pathology / Q000652:urine; D008297:Male; D008853:Microscopy; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D011379:Prognosis; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012720:Severity of Illness Index; D013997:Time Factors; D016482:Urinalysis / Q000379:methods*; D014556:Urine / Q000166:cytology*