Urine Protein-to-creatinine Research Articles

SIL7R concentrations in the serum reflect disease activity in the lupus kidney

ObjectivesEvaluation of disease activity in systemic lupus erythematosus (SLE) nephritis is a challenge, and repeated renal biopsies are usually needed in order to confirm a suspicion of flare. In a...

Big-endothelin 1 (big ET-1) and homocysteine in the serum of dogs with chronic kidney disease

This study was aimed at determining the serum concentration of homocysteine (Hcy) and big endothelin-1 (big ET-1, the precursor of endothelin) in dogs with chronic kidney disease (CKD) with and without hypertension, proteinuria and inflammation, in order to explore their role as biomarkers of hypertension associated with CKD. Hcy and big ET-1 were measured using an enzyme-linked immunosorbent assay and an enzymatic cyclic reaction, respectively, in dogs with CKD staged, as proposed by the International Renal Interest Society (IRIS), using serum creatinine, urinary protein to creatinine (UPC) ratio and systolic blood pressure, and classified as affected or not by inflammation based on the serum concentration of C-reactive protein (CRP).Serum Hcy was significantly higher in dogs of IRIS stages II, III and IV compared with controls and in proteinuric compared with non-proteinuric dogs. No differences relating to the degree of hypertension or to the CRP concentration were found. Serum big ET-1 significantly increased in dogs of IRIS stage IV compared with controls, in proteinuric compared with non-proteinuric dogs, in dogs with severe hypertension compared with those without hypertension, and in dogs with increased CRP compared to those with normal CRP concentrations. Hcy only correlated with serum creatinine but big ET-1 significantly correlated with serum creatinine, UPC ratio, systolic blood pressure, and increased CRP. In conclusion, both Hcy and big ET-1 increase in dogs with CKD. Although further research is needed, big ET-1, but not Hcy, may also be considered as a biomarker of hypertension.

Comparison of urine dipstick, sulfosalicylic acid, urine protein-to-creatinine ratio and a feline-specific immunoassay for detection of albuminuria in cats with chronic kidney disease.

The performance of the urine dipstick, sulfosalicylic acid (SSA), and urine protein-to-creatinine (UPC) tests for the detection of albuminuria was assessed in cats with chronic kidney disease (CKD). Two hundred and thirty-nine urine samples from 37 cats with CKD were used. Test results were dichotomized as either positive or negative, compared with those for the feline-specific rapid urine albumin immunoassay and test performance variables calculated for each test. A positive urine dipstick (≥ trace) and positive SSA (≥ 5 mg/dl), positive SSA alone or ≥ 2+ urine dipstick alone were indicative of albuminuria. In these cases, protein quantification would be warranted if proteinuria/albuminuria is persistent. In the case of a negative urine dipstick result the addition of the SSA added little diagnostic value. Of the tests investigated, the single best test for the detection of albuminuria was the UP/C (≥ 0.2) in which either a negative or positive test result provided useful information.

Evaluation of factors that affect analytic variability of urine protein-to-creatinine ratio determination in dogs

To determine whether preanalytic and analytic factors affect evaluation of the urinary protein-to-creatinine (UPC) ratio in dogs. 50 canine urine samples. The UPC ratio was measured to assess the intra-assay imprecision (20 measurements within a single session), the influence of predilution (1:10, 1:20, and 1:100) for urine creatinine concentration measurement, and the effect of storage at room temperature (approx 20°C), 4°C, and -20°C. The coefficient of variation at room temperature determined with the 1:20 predilution was < 10.0%, with the highest coefficients of variation found in samples with a low protein concentration or low urine specific gravity. This variability could result in misclassification of samples with UPC ratios close to the thresholds defined by the International Renal Interest Society to classify dogs as nonproteinuric (0.2), borderline proteinuric (0.21 to 0.50), or proteinuric (> 0.51). A proportional bias was found in samples prediluted 1:10, compared with samples prediluted 1:20 or 1:100. At room temperature, the UPC ratio did not significantly increase after 2 and 4 hours. After 12 hours at room temperature and at 4°C, the UPC ratio significantly increased. The UPC ratio did not significantly change during 3 months of storage at -20°C. The intra-assay precision of the UPC ratio was sufficiently low to avoid misclassification of samples, except for values close to 0.2 or 0.5. The optimal predilution ratio for urine creatinine concentration measurement was 1:20. A 1:100 predilution is recommended in samples with a urine specific gravity > 1.030. The UPC ratio must be measured as soon as samples are collected. Alternatively, samples should be immediately frozen to increase their stability and minimize the risk of misclassification of proteinuria.

Comparison of urine protein-to-creatinine ratio in urine samples collected by cystocentesis versus free catch in dogs

To assess whether urine protein-to-creatinine (UPC) ratios determined in urine samples collected by cystocentesis versus those collected by free catch provide similar diagnostic information for dogs. Evaluation study. 115 client-owned dogs evaluated because of various health problems requiring urinalysis or to screen for proteinuria in an area endemic for leishmaniasis. 230 paired urine samples, 1 collected by cystocentesis and 1 by free catch, were collected from the 115 dogs. The UPC ratio was determined in paired urine samples (n = 162) from 81 dogs with no indication of active inflammation according to urine sediment analysis. On the basis of the UPC ratio of urine sample collected by cystocentesis, dogs were classified as nonproteinuric (UPC ratio < 0.2), borderline proteinuric (UPC ratio of 0.2 to 0.5), or proteinuric (UPC ratio > 0.5), according to the International Renal Interest Society (IRIS). The correlation between UPC ratio in urine samples collected by cystocentesis and by free catch was strong (r(2) = 0.90); 75 of 81 (92.6%) dogs had UPC ratios from both urine samples that resulted in classification in the same IRIS substage with a kappa coefficient of 0.83. The UPC ratio in dogs was minimally affected in urine samples collected by free catch, thus allowing correct grading of proteinuria with this method. The high reliability of the UPC ratio in free-catch urine samples coupled with the ease of collection should increase the use of this value for assessment of proteinuria.

Evaluation of a urine dipstick test for confirmation or exclusion of proteinuria in dogs

To evaluate a urine dipstick test as a possible replacement for urine protein-to-creatinine (UPC) ratio for identifying proteinuria in dogs. 507 urine samples from adult dogs. Urine dipstick, UPC ratio, specific gravity (USG), and sediment testing were performed on 507 samples. With UPC ratio as the reference criterion, diagnostic accuracy of the urine dipstick test was calculated for the entire data set and for urine samples grouped by USG (< or = 1.012 or > 1.012; < 1.030 or > or = 1.030). A UPC ratio < 0.2 was used to indicate absence of proteinuria. The sensitivity of the urine dipstick test for detection of proteinuria was > 90% when 0 mg of protein/dL (a 0+ result) was used to indicate a negative test result, and the specificity ranged from 40% to 60%, depending on the USG. Sensitivity decreased to a range of 56% to 81% when 30 mg of protein/dL (a 1+ result) was used as the cutoff, depending on the USG, but the specificity increased to > 90%. The likelihood of correctly identifying nonproteinuric dogs was low when the USG was < or = 1.012, particularly when samples with a 1+ result were considered negative. For dogs with a dipstick-test result of 1+ and USG < or = 1.012, proteinuria should be assessed by use of the UPC ratio; dogs with a USG value > 1.012 are likely nonproteinuric. When used together, the urine dipstick test and USG measurement were reliable as a rapid alternative to UPC ratio determination in dogs in this study.

Increase in proteinuria &gt;200 mg/g after late rejection is associated with poor graft survival

There is no information on the effects of proteinuria on outcomes following rejection. We addressed this question in a retrospective study of 925 kidney transplant recipients between January 2003 and December 2007. Selection criteria were based on (i) biopsy proven diagnosis of a first episode of acute rejection, and (ii) available data on urine protein to creatinine (UPC) ratios at baseline (lowest serum creatinine before biopsy), time of biopsy and 1 month after biopsy. We examined the effects of a change in UPC (DeltaUPC = UPC 1 month after biopsy-baseline UPC) on outcomes. We identified 82 patients with both acute rejection and available data on proteinuria. Mean time (+/-SE) to acute rejection was 19 +/- 2.3 months, and patients were followed up for 38.7 +/- 2.6 months after transplant. Median DeltaUPC was 200 mg/g (95% confidence interval 0.00 to 0.300). Forty-two patients had a DeltaUPC > or =200 (high proteinuria group). Baseline characteristics were similar between high and low proteinuria groups except for more induction therapy with interleukin-2 receptor blockade in the former (71 vs. 47%, P = 0.04). Patient with DeltaUPC > or =200 had higher rates of graft loss (26 vs. 15%, P = 0.01) or combined graft loss or death (38 vs. 20%, P = 0.002 by log-rank). In univariate and multivariate Cox regression analyses, DeltaUPC > or =200 mg/g, sirolimus therapy 1 month after rejection and re-transplant status were significant factors associated with death-censored graft loss (hazard ratio (HR) 4.4, 14.9 and 6.2, P < or = 0.008) or combined graft loss or patient death (HR 3.8, 6.5 and 3.9, P < or = 0.03). Conclusions. An increase in proteinuria > or =200 mg/g after late acute rejection is associated with poor graft and patient outcomes. Clinical trials are needed to determine whether post-rejection anti-proteinuric strategies improve outcomes.

Evaluation of a commercial in-house test kit for the semi-quantitative assessment of microalbuminuria in cats

Proteinuria was assessed in 100 randomly selected sick cats and 22 healthy cats by means of the urine protein:creatinine ratio, a traditional urine "dipstick" and a commercial ELISA-based dipstick designed to detect microalbuminuria (MA) semi-quantitatively. In addition the repeatability and reproducibility of the MA test was assessed by comparing results of five replicate tests of 26 urine samples, interpreted by two different readers. Discrepancies existed in the replicate test result in 23 and 27% of the samples examined by reader 1 and 2, respectively, and on several occasions this discrepancy was between whether the sample was "positive" or "negative" for MA. The inter-reader agreement was good (kappa=0.75), but again discrepancies were noted and part of the reason for these problems appeared to be the necessary subjectivity in the interpretation of colour changes when reading test results. Proteinuria was significantly (P< or =0.014) more prevalent in the sick than the healthy cats with 36 and 9%, respectively, having detectable MA, 34 and 5%, respectively, having a urine protein to creatinine (UPC) ratio >0.5, and 84 and 9%, respectively, having positive urine protein dipstick analysis. There was a moderate significant correlation between UPC ratio and MA concentrations (r(s)=0.68, P<0.0001). While 13/87 cats with a UPC ratio < or =0.5 had positive MA results, 10/84 cats with negative MA results had a UPC ratio >0.5, and none of these had evidence of lower urinary tract disease. This study confirmed that MA and proteinuria are commonly seen in cats with a variety of diseases, but they are not necessarily both elevated, and the UPC ratio can be elevated without an increase in MA results. Furthermore, some repeatability problems were demonstrated with the semi-quantitative MA test. These findings demonstrate that the semi-quantitative MA test should not be relied on as the sole determinant of proteinuria.

Clinical Trial to Evaluate Omega-3 Fatty Acids and Alternate Day Prednisone in Patients with IgA Nephropathy

This randomized, placebo-controlled, double-blind trial evaluated the role of prednisone and omega 3 fatty acids (O3FA) in patients with IgA nephropathy. Entry criteria were (1) biopsy-proven IgA nephropathy, (2) estimated GFR > or = 50 ml/min per 1.73 m2, and (3) moderate to severe proteinuria. Thirty-three patients were randomly assigned to receive prednisone 60 mg/m2 every other day for 3 mo, then 40 mg/m2 every other day for 9 mo, then 30 mg/m2 every other day for 12 mo (prednisone group); 32 were randomly assigned to receive O3FA 4 g/d for 2 yr (1.88 g eicosapentaenoic acid, 1.48 g docosahexaenoic acid; O3FA group); and 31 were randomly assigned to receive placebo (placebo group). Most (73%) patients completed 2 yr of treatment. Randomly assigned patients who were hypertensive were given enalapril 2.5 to 40 mg/d. The primary end point was time to failure, defined as estimated GFR <60% of baseline. An overall significance level of 0.10 was used. The three groups were comparable at baseline except that the O3FA group had higher urine protein to creatinine (UP/C) ratios than the placebo group (P = 0.003). Neither treatment group showed benefit over the placebo group with respect to time to failure, with 14 patient failures overall (two in the prednisone group, eight in the O3FA group, and four in the placebo group). The primary factor associated with time to failure was higher baseline UP/C ratios (P = 0.009). Superiority of prednisone or O3FA over placebo in slowing progression of renal disease was not demonstrated in this study. However, the relatively short follow-up period, inequality of baseline UP/C ratios, and small numbers of patients precludes definitive conclusions.

Renal function in pediatric patients with beta-thalassemia major.

In patients with beta-thalassemia major, the most important cause of mortality and morbidity is organ failure due to deposits of iron. In this study, the nature of the kidney injury and possible pathogenetic factors were investigated. Seventy children with beta-thalassemia major and 14 age and sex-matched healthy children were involved in the study. Blood and timed urine samples were obtained for hematological and biochemical tests. The mean values of blood urea nitrogen (BUN), serum creatinine, creatinine clearance, serum sodium, urine osmolality, fractional excretion of sodium, potassium, and uric acid were not statistically different between the groups. Serum levels of potassium, phosphorus, and uric acid and the urine volume, high urinary protein to creatinine (UP/Cr), urinary N-acetyl-beta-D-glucosaminidase to creatinine (UNAG/Cr), and urinary malondialdehyde to creatinine, (UMDA/Cr) and the tubular phosphate reabsorption (TRP) values were statistically different between two groups (P<0.05). Increased serum levels of potassium, phosphorus, and uric acid in the patient group were attributed to the rapid erythrocyte turnover. The presence of high UP/cr, UNAG/Cr and UMDA/Cr ratios shows that in these patients with proximal renal tubular damage may be secondary to oxidative lipid peroxidation mediated by the iron overload.