[Clinical significance of hyaline casts in the new CKD risk classification (KDIGO 2009)]

Chronic kidney disease (CKD) significantly contributes to the increased number of dialysis patients with end stage renal disease. A new CKD risk classification (KDIGO 2009) established in 2011, which is defined by albuminuria and estimated glomerular filtration rate (eGFR) values, demonstrates the relative risks of CKD in great detail. In this study, we evaluated the clinical significance of urinary casts by categorizing a risk Group 1 to 5 according to the KDIGO 2009 classification. In the high risk CKD group (risk group 3 and over), we found a significantly higher number of patients who had > 100 hyaline casts/whole field (WF) in their urine than those that had < 100 hyaline casts/WF. Further, we determined the diagnostic accuracy for the high risk CKD group when the cutoff value for the number of hyaline casts was set at > or = 100 hyaline casts/WF (sensitivity: 44.7%, specificity: 96.5%). The eGFR value was significantly lower in the group with > or = 100 hyaline casts/WF, particularly in hypertensive patients, than that in the group with < 100 hyaline casts/ WF. Of interest is that the eGFR value was significantly lower in patients with 100-999 hyaline casts/WF and > or = 1,000 hyaline casts/WF than that in patients with < 100 hyaline casts/WF in A1 stage. Thus, our present study suggests that the presence of > or = 100 hyaline casts/WF indicates decreased eGFR, and the urinary casts counting may be important and useful for the screening and early detection of high-risk CKD.