The value of urine citrate/calcium ratio in the estimation of risk of urolithiasis.

The urine saturation is considered as the better parameter for the estimation of risk of urolithiasis than any single urinary constituent. However, the determination of urine saturation is unsuitable for routine clinical practice. To evaluate a simpler and cheaper test than urine saturation for distinguishing stone formers from healthy individuals, urinary citrate/calcium ratio was determined in 30 children with urolithiasis, 36 children with isolated hematuria, and 15 healthy control children. The ratio was significantly lower in urolithiasis group comparing to controls, and significantly higher in hematuria than in urolithiasis group. The cut-off points between normal children and children with urolithiasis, accuracy, specificity and sensitivity were determined and compared with those of the urine saturation calculated with the computer program EQUIL 2. The data mining Weka software was used for the determination of the cut-off points. Children with urolithiasis had citrate/calcium ratio below 1.38 and urine saturation above 5.285. The citrate/calcium ratio showed in comparison to urine saturation similar high accuracy (91.11 vs. 88.89%), somewhat lesser specificity (73.33% vs. 93.33%) and much better sensitivity (100% vs. 86.89%) in discrimination of stone formers from normal children. The advantage in comparison to urine saturation is that it can be easily performed in clinical practice.