Determination of performance characteristics of methods used for total protein and albumin measurements in urine

Determination of urinary total protein and albumin is used widely in clinical laboratories, but there is no agreement about which method should be used, since present methods have various advantages and disadvantage. The major aim is to compare analytical performances of methods for measurement of urinary total protein including turbidimetric method used in our biochemistry laboratory, Modfied Purdy method, Lowry method, Bradford method and also for methods urinary albumin measurement includig imminotürbidimetric and immünonephelometric methods used in our laboratory. In retrospective study, 977 patients whose their urinary total protein and albumin measurements were done in bichemistry laboratory, Faculty of Medicine, KTU were included. In prospective study, urine samples which their total protein levels were measured by turbidimetric method were measured also by Modfied Purdy ,Lowry,and Bradford methods.Urine samples measured by imminotürbidimetric method for urinary albumin measurement were studied by immünonephelometric method .In the retrospective study ,a significant positive correlation between total protein and albumin levels was found. In the prospective study, a significant statistical difference was found among urinary total protein methods. Analytical sensitivity of turbidimetric method was found to be the best among total protein methods. For urinary albumin determination, a statistically significant difference (p=0,024) and a strong positive correlation (r=0.992) between imminotürbidimetric and immünonephelometric methods were found.It was concluded that both total protein and albumin measurement in urine should be done to evaluate kidney functions.