HOW TO INTERPRET URINARY PROTEINURIA AS A MARKER OF HYPERTENSIVE NEPHROPATHY?

Abstract

Objective: Proteinuria may be the first sign of underlying nephropathy. It is pathological when the value is higher than 0.15 g/24h. The gold standard of quantification is the determination of proteinuria on the collection of urine for 24 hours, however, in view of the errors related to the collection and storage, we adopted another mode of expression. The objective of our work is to evaluate the correlation between the results of the 24 hours proteinuria and the proteinuria calculated by ratio (proteinuria/creatinuria). Design and method: Our prospective comparative study was performed on 100 24-hour urine samples (100 patients). We recorded the 24h diuresis and we determined the proteinuria by the pyrogallol red method (Advia 1800) and the urinary creatinine by the compensated jaffa method (Cobas 6000). Statistical evaluation was performed using GraphPad Prism software7 Results: Our results show: the average proteinuria of 24 h is 309.7 mg/24H (the norms lower than 150 mg/24H) and the average proteinuria/creatinine ratio is 283.7 mg/g (the norms lower than 300 mg/g). Of the 100 samples, only 5 patients (5%) showed pathological 24-hour proteinuria with a proteinuria/creatinuria ratio within the norms, and one patient (1%) had 24-hour proteinuria within the norms and a high proteinuria/creatinuria ratio, 25 patients (25%) had a simultaneous increase in 24-hour proteinuria and in the proteinuria/creatinuria ratio The remaining 69 patients (69%) had 24-hour proteinuria and a proteinuria/creatinuria ratio within the physiological norms The comparative study found a significant difference p<0.0001 with a significant positive Pearson correlation R 2 = 0.92. The agreement of the 24 h proteinuria tests and the Proteinuria/creatinuria ratio is modelled by the Bland and Altman diagram which finds a bias of 1.02 and a Confidence interval 95%] 0.046-1.36 [. Conclusions: Therefore it is not necessary to carry out a 24-hour urine collection, preferring measurements on urine samples from the first morning micturition. In order to overcome the numerous false positives and negatives linked to the collection of 24-hour urine, this examination is a good alternative.