Evaluation of methods for rapid microalbuminuria screening in kidney diseased patients

Abstract

One of the criteria for chronic kidney disease detection is determination of microalbuminuria. This analysis was performed to evaluate accuracy of three useful methods for microalbuminuria detection in 24h urine collection and in the morning urine specimen calculated from urine albumin creatinine ratio, or with a dipstick in patients with different kidney diseases or kidney function. Microalbuminuria was detected in 74 patients referred to the Outpatient Nephrology Department for kidney function determination or regular nephrology checking. Albumin concentration determined using immunonephelometry was lower than 300 mg/day. Discriminates cutoff values for spot urine test strip and albumin creatinin ratio in predicting 24 h protein'threshold' excretion were determined using ROC analysis. Mean value of 24 h microalbuminuria was 80.3 mg/24 h, and value >30 mg/24 h was present in 71.8% of patient. Correlation coefficients between dipstick microalbuminuria or albumin/creatinine ratio in a spot urine specimen and 24 h microalbuminuria were 0.709 and 0.598 (p<0.0001). For pathological value of 24 h microalbuminuria >30 mg/24 h, the coresponding dipstick microalbuminuria value was > or = 20 mg/L (AUC 0.849, specificity 95%, positive predictive value 97.3%), and > or = 3.55 mg albumin/mmol creatinine ratio (AUC 0.914, specificity 90% and positive predictive value 95.5%). No difference was found between dipstick mikroalbuminuria and albumin/creatinine ratio value. In addition, albumin/creatinine ratio value from 24 h urine was similar to the value obtained from the spot urine sample. Obtained results indicated that albuminuria could be determined accurately in spot urine either with the Micral test strip or with albumin creatinine ratio.