Comparison of 24-jour urinary protein and -to-creatinine ratio in the assessment of proteinuria

Abstract EN

To determine the correlation between protein-to-creatinine ratio (PCR) and 24-hour urinary protein (UP), we measured proteinuria in 68 patients attending the nephrology clinic at Jordan University Hospital by 24-hour urine protein excretion and protein-to-creatinine ratio.

The cutoff values for spot urine protein-to-creatinine ratio in predicting 24-hour protein "threshold" excretion of 0.5, 1.0 and 3.5 g / day were determined using receiver operating characteristic curves.

A very good correlation (r= 0.832, P< 0.0001) was found between spot urine protein-to-creatinine ratio and 24-hour urine protein excretion.

Bland-Altman plot showed the two tests had reasonable limits of agreement at low level of protein excretion but the limits became wider as the protein excretion increased.

For protein excretion < 2.0 g / day, the limits of agreement of spot urine (PCR) and (UP) were +1.48 and -1.2 g / day.

The spot urine protein-to-creatinine ratios of 0.72 (sensitivity 0.97; specificity 1.0), 1.2 (0.97; 0.89) and 3.23 (1.0; 0.86) mg / mg reliably predicted 24-hour urine total protein equivalent "thresholds" of 0.5, 1.0 and 3.5 g / day, respectively.

We conclude that the protein-to-creatinine ratio in spot urine specimens is an accurate, convenient, and reliable method to estimate the protein excretion in urine.

However, the protein-to-creatinine ratio will likely be within clinically acceptable limits only when proteinuria is at reasonably low levels.