A Dipstick Protein and Specific Gravity Algorithm Accurately Predicts Pathological Proteinuria

Specific Gravity Improves Identification of Clinically Significant Quantitative Proteinuria from the Dipstick Urinalysis

Key Points

Background

CKD is often underdiagnosed during early stages when GFR is preserved because of underutilization of testing for quantitative urine albumin-to-creatinine ratio (UACR) or urine protein-to-creatinine ratio (UPCR). Semiquantitative dipstick proteinuria (DSP) on urinalysis is widely obtained but not accurate for identifying clinically significant proteinuria.

Methods

We identified all patients with a urinalysis and UACR or UPCR obtained on the same day at a tertiary referral center. The accuracy of DSP alone or in combination with specific gravity (SG) against a gold-standard UACR ≥30 mg/g or UPCR ≥0.15 g/g, characterizing clinically significant proteinuria, was evaluated using logistic regression. Models were internally validated using ten-fold cross-validation. The SG for each DSP above which significant proteinuria is unlikely was determined.

Results

Of 11,229 patients, clinically significant proteinuria was present in 4073 (36%). The area under the receiver-operating characteristic curve (95% confidence interval) was 0.77 (0.76 to 0.77) using DSP alone and 0.82 (0.82 to 0.83) in combination with SG (P < 0.001), yielding a specificity of 0.93 (SEM=0.02) and positive likelihood ratio of 9.52 (SEM=0.85). The optimal SG cutoffs to identify significant proteinuria were ≤1.0012, 1.0238, and 1.0442 for DSP of trace, 30, and 100 mg/dl, respectively. At any SG, a DSP ≥300 mg/dl was extremely likely to represent significant proteinuria.

Conclusions

Adding SG to DSP improves recognition of clinically significant proteinuria and can be easily used to identify patients with early stage CKD who may not have otherwise received a quantified proteinuria measurement for both clinical and research purposes.

Sex differences in the evaluation of proteinuria using the urine dipstick test

Background

The urine protein dipstick test is widely used, but false-positive and false-negative results may occur. This study aimed to compare the urine protein dipstick test with a urine protein quantification method.

Methods

The data were extracted using the Abbott Diagnostic Support System, which analyzes the inspection results using multiple parameters. This study included 41,058 specimens tested using the urine dipstick test and protein creatinine ratio from patients aged ≥18 years. The proteinuria creatinine ratio was classified according to the Kidney Disease Outcomes Quality Initiative guidelines.

Results

Urine protein on the dipstick test was negative in 15,548 samples (37.9%), trace in 6,422 samples (15.6%), and ≥1+ in 19,088 samples (46.5%). Among the trace proteinuria samples, A1 (<0.15 g/gCr), A2 (0.15-0.49 g/gCr), and A3 (≥0.5 g/gCr) category proteinuria accounted for 31.2, 44.8, and 24.0% of samples, respectively. All trace proteinuria specimens with a specific gravity of <1.010 were classified as A2 and A3 category proteinuria. In the trace proteinuria cases, women had a lower specific gravity and a higher percentage of A2 or A3 category proteinuria than men. The sensitivity in the "dipstick proteinuria" ≥ trace" group was higher than that in the "dipstick proteinuria ≥ 1+" group within the lower specific gravity group. The sensitivity in the "dipstick proteinuria ≥ 1+" group was higher for men than for women, and the sensitivity in the "dipstick proteinuria ≥ trace" group was higher than that in the "dipstick proteinuria ≥ 1+" group for women.

Conclusion

Pathological proteinuria assessment requires caution; this study suggests that evaluating the specific gravity of urine specimens with trace proteinuria is essential. Particularly for women, the sensitivity of the urine dipstick test is low, and caution is needed even with trace specimens.

Diagnostic accuracy of urine dipstick testing for albumin-to-creatinine ratio and albuminuria: A systematic review and meta-analysis

Background

The accuracy of urine dipsticks to detect increased albuminuria is uncertain. We aimed to assess the diagnostic accuracy of urine dipsticks for detecting albuminuria.

Methods

A systematic review of studies that assessed the diagnostic accuracy of urine dipstick testing for detecting albuminuria has been conducted (using as reference standard the albuminuria in a 24-hour sample or the albumin-to-creatinine ratio) in Scopus, PubMed, and Google Scholar. The risk of bias of the included studies has been assessed using the Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) tool. Whenever possible, we performed meta-analyses for sensitivity and specificity. The certainty of the evidence has also been assessed using the Grading of Recommendations Assessment, Development, and Evaluation methodology.

Results

A total of 14 studies have been included in this review, having assessed all albumin-to-creatinine ratio (ACR) as assessed standard. Each study used different dipstick types. The resulting pooled sensitivity and specificity for each cutoff point were as follows: for ACR >30 mg/g (13 studies): 0.82 (95% confidence interval: 0.76–0.87) and 0.88 (0.83–0.91); for ACR 30–300 mg/g (7 studies): 0.72 (0.68–0.77) and 0.82 (0.76–0.89); and for ACR >300 mg/g (7 studies): 0.84 (0.71–0.90) and 0.97 (0.95–0.99), respectively. An overall high risk of bias, an important heterogeneity in all pooled analysis, and a very low certainty of the evidence have been found.

Conclusions

Pooled sensitivity and specificity of urine dipsticks have been calculated for different ACR cutoff points. However, the dipstick types differed across studies, and the certainty of the evidence was very low. Thus, further well-designed studies are needed to reach more confident estimates and to assess accuracy differences across dipstick types.

Registration

PROSPERO (CRD42019124637).

Longitudinal Outcomes of COVID-19-Associated Collapsing Glomerulopathy and Other Podocytopathies

BACKGROUND

The long-term outcome of COVID-19-associated collapsing glomerulopathy is unknown.

METHODS

We retrospectively identified 76 native kidney biopsies from patients with history of COVID-19 between March 2020 and April 2021. Presenting and outcome data were obtained for all 23 patients with collapsing glomerulopathy and for seven patients with noncollapsing podocytopathies. We performed APOL1 genotyping by Sanger sequencing, immunostaining for spike and nucleocapsid proteins, and in situ hybridization for SARS-CoV-2.

RESULTS

The 23 patients with COVID-19-associated collapsing glomerulopathy were median age 57 years (range, 35-72), included 16 men, and were predominantly (91%) Black. Severity of COVID-19 was mild or moderate in most (77%) patients. All but one patient presented with AKI, 17 had nephrotic-range proteinuria, and six had nephrotic syndrome. Fourteen (61%) patients required dialysis at presentation. Among 17 patients genotyped, 16 (94%) were high-risk APOL1. Among 22 (96%) patients with median follow-up at 155 days (range, 30-412), 11 (50%) received treatment for COVID-19, and eight (36%) received glucocorticoid therapy for podocytopathy. At follow-up, 19 (86%) patients were alive, and 15 (68%) were dialysis free, including seven of 14 who initially required dialysis. The dialysis-free patients included 64% (seven of 11) of those treated for COVID-19 and 75% (six of eight) of those treated with glucocorticoids for podocytopathy. Overall, 36% achieved partial remission of proteinuria, 32% had no remission, and 32% reached combined end points of ESKD or death. Viral infection of the kidney was not detected.

CONCLUSIONS

Half of 14 patients with COVID-19-associated collapsing glomerulopathy requiring dialysis achieved dialysis independence, but the long-term prognosis of residual proteinuric CKD remains guarded, indicating a need for more effective therapy.

Kidney Function after Treatment for Childhood Cancer: A Report from the St. Jude Lifetime Cohort Study

BACKGROUND

Survivors of childhood cancer may be at increased risk for treatment-related kidney dysfunction. Although associations with acute kidney toxicity are well described, evidence informing late kidney sequelae is less robust.

METHODS

To define the prevalence of and risk factors for impaired kidney function among adult survivors of childhood cancer who had been diagnosed ≥10 years earlier, we evaluated kidney function (eGFR and proteinuria). We abstracted information from medical records about exposure to chemotherapeutic agents, surgery, and radiation treatment and evaluated the latter as the percentage of the total kidney volume treated with ≥5 Gy (V5), ≥10 Gy (V10), ≥15 Gy (V15), and ≥20 Gy (V20). We also used multivariable logistic regression models to assess demographic and clinical factors associated with impaired kidney function and Elastic Net to perform model selection for outcomes of kidney function.

RESULTS

Of the 2753 survivors, 51.3% were men, and 82.5% were non-Hispanic White. Median age at diagnosis was 7.3 years (interquartile range [IQR], 3.3-13.2), and mean age was 31.4 years (IQR, 25.8-37.8) at evaluation. Time from diagnosis was 23.2 years (IQR, 17.6-29.7). Approximately 2.1% had stages 3-5 CKD. Older age at evaluation; grade ≥2 hypertension; increasing cumulative dose of ifosfamide, cisplatin, or carboplatin; treatment ever with a calcineurin inhibitor; and volume of kidney irradiated to ≥5 or ≥10 Gy increased the odds for stages 3-5 CKD. Nephrectomy was significantly associated with stages 3-5 CKD in models for V15 or V20.

CONCLUSIONS

We found that 2.1% of our cohort of childhood cancer survivors had stages 3-5 CKD. These data may inform screening guidelines and new protocol development.

Urinary strips for protein assays: easy to do but difficult to interpret!

Urine samples can be readily obtained from patients in everyday clinical practice. Therefore, the availability of urine allows physicians to obtain relevant clinical information in a timely manner. Since the measurement of urinary protein levels is essential in diagnosing and treating a host of diseases, the potential detection of urinary proteins by urinary strips in an easy, quick, and cheap way is very attractive. However, to ensure optimal use of urinary strips, one needs to be aware of their characteristics and their limitations. In this review, we discuss the characteristics of the urinary strips available for testing urinary protein levels and for detecting urinary albumin. We then consider their analytical performances in their most widely used clinical applications (e.g., in pregnancy, chronic kidney disease, diabetes, and screening of the general population).

Evaluation of Hypertension, Proteinuria, and Abnormalities of Body Weight in Italian Adolescents Participating in the World Kidney Days

INTRODUCTION

World Kidney Day (WKD) was promoted by the Italian Kidney Foundation and the Italian Society of Nephrology for raising awareness, detection, prevention, and treatment of kidney diseases. The Italian WKD focused on the "School Project" by screening students attending the fifth year of high school. The main goal of the "School Project" was to assess in healthy adolescents the presence of hypertension (HTN) and proteinuria; as well as to evaluate potential interrelations between overweight, obesity (both measured with different anthropometric methods), blood pressure (BP) levels, and proteinuria. The ancillary goal was to have an estimate of awareness on some nephrology topics.

METHODS

The study population consisted of 17- to 19-year-old students. HTN was defined as systolic BP (SBP) ≥140 mm Hg and/or diastolic BP (DBP) ≥90 mm Hg. Isolated systolic hypertension (ISH) was defined as SBP ≥140 mm Hg and DBP <90 mm Hg; isolated diastolic hypertension as SBP <140 mm Hg and DBP ≥90 mm Hg; systolic and diastolic hypertension as SBP ≥140 mm Hg and DBP ≥90 mm Hg; pre-hypertension as SBP >120 mm Hg but <140 mm Hg or DBP >80 mm Hg but <90 mm Hg; and optimal BP as SBP ≤120 mm Hg and DBP ≤80 mm Hg. Urine tests were performed with a dipstick; the subjects were regarded as proteinuric when the urine dipstick was positive (proteinuria ≥30 mg/dL). Body weight, height, and waist circumference (WC) were measured; body mass index (BMI), waist-to-height ratio (WHtR), and conicity index (Ci) were calculated. According to the BMI, the following classifications were adopted: underweight (<18.5 kg/m2), normal weight (18.5-24.9 kg/m2), overweight (25-29.9 kg/m2), class-I obesity (30-34.9 kg/m2), class-II obesity (35-39.9 kg/m2), class-III obesity (≥40 kg/m2).

RESULTS

Data from 12,125 students (45.6% males) were evaluated. HTN was found in 1,349 participants (11.1%; 61.1% male), and ISH was present in 7.4%. Overweight (24.1%) and class-I (6%), -II (3.6%), and -III (1%) obesity were present in hypertensive participants. Compared to participants with normal BP, hypertensive participants had a higher BMI (p < 0.001), WC (p < 0.001), and WHtR (p < 0.001); whereas the Ci was not different (p = 0.527). Multivariate linear regression analysis showed that both WC and BMI were predictors of abnormal SBP and DBP (p < 0.001) both in males and females. Proteinuria was present in 14.8, 13.8, 14.7, and 14.7% of all normal weight, overweight, obese, and all subjects, respectively. In addition, no association was found between body weight, proteinuria, and BP.

CONCLUSION

This study shows that overweight and obesity were significantly associated to HTN in Italian adolescents. BMI and WC were predictors of SBP and DBP. The occurrence of proteinuria was quite similar to that of HTN, but it was not associated with anthropometric indicators or HTN.

Possible beneficial association between renin-angiotensin-aldosterone-system blockade usage and graft prognosis in allograft IgA nephropathy: a retrospective cohort study

BACKGROUND

Although immunoglobulin A nephropathy (IgAN) is associated with an increased risk of renal allograft failure, evidences for its treatment, including renin-angiotensin-aldosterone system blockade (RAASB) usage, remain limited.

METHODS

In this bi-center retrospective cohort study, we included patients who were recently diagnosed with IgAN through allograft biopsies. We identified their 6-month antihypertensive medication prescriptions and investigated the association between the medication types, albuminuria changes, and risk of 5-year death-censored-graft-failure (DCGF). The mixed effect model and cox regression analysis were used.

RESULTS

A total of 464 allograft IgAN patients were included: 272, 38, 33, and 121 patients in the no antihypertensive medication, single agent RAASB, single agent beta blocker (BB)/calcium channel blocker (CCB), and combination therapy groups, respectively. High-degree albuminuria after 6 months of allograft IgAN diagnosis was an important prognostic parameter and a partial mediator for the association between the subgroups and 5-year DCGF. The usage of single RAASB was associated with decrement of albuminuria from allograft IgAN diagnosis (P for interaction = 0.03). The single BB/CCB group demonstrated significantly worse prognosis than the single RAASB group (adjusted hazard ratio, 2.76 [1.09-6.98]; P = 0.03).

CONCLUSIONS

In conclusion, RAASB may be beneficial for graft prognosis in early allograft IgAN patients who require single antihypertensive medication therapy, by means of reducing albuminuria. Further investigation of treatment strategy in allograft IgAN is warranted.

Analytical verification of 12 most commonly used urine dipsticks in Croatia: comparability, repeatability and accuracy

Introduction

Variability among manufacturers of urine dipsticks, respective to their accuracy and measurement range, may lead to diagnostic errors and thus create a serious risk for the patient. Our aims were to determine the level of agreement between 12 most commonly used urine dipsticks in Croatia, examine their accuracy for glucose and total protein and to test their repeatability.

Materials and methods

A total of 75 urine samples were used to examine comparability and accuracy of 12 dipstick brands (Combur 10 TestM, ChoiceLine 10, Combur 10 TestUX, ComboStik 10M, ComboStik 11M, CombiScreen 11SYS, CombiScreen 10SL, Combina 13, Combina 11S, Combina 10M, UriGnost 11, Multistix 10SG). Agreement between each dipstick and the reference (Combur 10 TestM) was expressed as kappa coefficient (acceptable κ ≥ 0.80). Accuracy for glucose and total protein was tested by comparison with quantitative measurements on analysers: AU400 (Beckman Coulter, USA), Cobas 6000 c501 (Roche Diagnostics, Germany) and Architect plus c4000 (Abbott, USA). Repeatability was assessed on 20 replicates (acceptable > 90%).

Results

Best agreement was achieved for glucose, total protein and nitrite (11/11, k > 0.80) and the lowest for bilirubin (5/5, k < 0.60). Sensitivities for total protein were 41-75% (AU400) and 56-92% (Cobas and Architect); while specificities were 41-75% (AU400, Cobas, Architect). Dipsticks' sensitivity and specificity for glucose were 68-98%. Most of the dipsticks showed unacceptable repeatability (6/12, < 90%) for one parameter, most prominently for pH (3/12, < 90%).

Conclusions

Most commonly used dipsticks in Croatia showed low level of agreement between each other. Moreover, their repeatability varies among manufacturers and their accuracy for glucose and proteins is poor.

The risk of death associated with proteinuria in heart failure is restricted to patients with an elevated blood urea nitrogen to creatinine ratio

BACKGROUND

Renal dysfunction (RD) is associated with reduced survival in HF; however, not all RD is mechanistically or prognostically equivalent. Notably, RD associated with "pre-renal" physiology, as identified by an elevated blood urea nitrogen to creatinine ratio (BUN/Cr), identifies a particularly high risk RD phenotype. Proteinuria, another domain of renal dysfunction, has also been associated with adverse events. Given that several different mechanisms can cause proteinuria, we sought to investigate whether the mechanism underlying proteinuria also affects survival in HF.

METHODS AND RESULTS

Subjects in the Studies of Left Ventricular Dysfunction (SOLVD) trial with proteinuria assessed at baseline were studied (n=6439). All survival models were adjusted for baseline characteristics and estimated glomerular filtration rate (eGFR). Proteinuria (trace or 1+) was present in 26% and associated with increased mortality (HR=1.2; 95% CI, 1.1-1.3, p=0.006). Proteinuria >1+ was less common (2.5%) but demonstrated a stronger relationship with mortality (HR=1.9; 95% CI, 1.5-2.5, p<0.001). In patients with BUN/Cr in the top tertile (≥17.3), any proteinuria (HR=1.3; 95% CI, 1.1-1.5, p=0.008) and >1+ proteinuria (HR=2.3; 95% CI, 1.7-3.3, p<0.001) both remained associated with mortality. However, in patients with BUN/Cr in the bottom tertile (≤13.3), any proteinuria (HR=0.95; 95% CI, 0.77-1.2, p=0.63, p interaction=0.015) and >1+ proteinuria (HR=1.3; 95% CI, 0.79-2.2, p=0.29, p interaction=0.036) were not associated with worsened survival.

CONCLUSION

Analogous to a reduced eGFR, the mechanism underlying proteinuria in HF may be important in determining the associated survival disadvantage.

Diagnostic Accuracy of Urine Protein/Creatinine Ratio Is Influenced by Urine Concentration

Background

The usage of urine protein/creatinine ratio to estimate daily urine protein excretion is prevalent, but relatively little attention has been paid to the influence of urine concentration and its impact on test accuracy. We took advantage of 24-hour urine collection to examine both urine protein/creatinine ratio (UPCR) and daily urine protein excretion, with the latter as the reference standard. Specific gravity from a concomitant urinalysis of the same urine sample was used to indicate the urine concentration.

Methods

During 2010 to 2014, there were 540 adequately collected 24h urine samples with protein concentration, creatinine concentration, total volume, and a concomitant urinalysis of the same sample. Variables associated with an accurate UPCR estimation were determined by multivariate linear regression analysis. Receiver operating characteristic (ROC) curves were generated to determine the discriminant cut-off values of urine creatinine concentration for predicting an accurate UPCR estimation in either dilute or concentrated urine samples.

Results

Our findings indicated that for dilute urine, as indicated by a low urine specific gravity, UPCR is more likely to overestimate the actual daily urine protein excretion. On the contrary, UPCR of concentrated urine is more likely to result in an underestimation. By ROC curve analysis, the best cut-off value of urine creatinine concentration for predicting overestimation by UPCR of dilute urine (specific gravity ≦ 1.005) was ≦ 38.8 mg/dL, whereas the best cut-off values of urine creatinine for predicting underestimation by UPCR of thick urine were ≧ 63.6 mg/dL (specific gravity ≧ 1.015), ≧ 62.1 mg/dL (specific gravity ≧ 1.020), ≧ 61.5 mg/dL (specific gravity ≧ 1.025), respectively. We also compared distribution patterns of urine creatinine concentration of 24h urine cohort with a concurrent spot urine cohort and found that the underestimation might be more profound in single voided samples.

Conclusions

The UPCR in samples with low or high specific gravity is more likely to overestimate or underestimate actual daily urine protein amount, respectively, especially in a dilute urine sample with its creatinine below 38.8 mg/dL or a concentrated sample with its creatinine above 61.5 mg/dL. In particular, UPCR results should be interpreted with caution in cases that involve dilute urine samples because its overestimation may lead to an erroneous diagnosis of proteinuric renal disease or an incorrect staging of chronic kidney disease.

Dipstick proteinuria is an independent predictor of high on treatment platelet reactivity in patients on clopidogrel, but not aspirin, admitted for major adverse cardiovascular events

The effectiveness of aspirin and clopidogrel in patients with chronic kidney disease (CKD) suffering from acute cardiovascular events is unclear. High on treatment platelet reactivity (HTPR) has been associated with worse outcomes. Here, we assessed the association of dipstick proteinuria (DP) and renal function on HTPR and clinical outcomes. Retrospective cohort analysis of 261 consecutive, non-dialysis patients admitted for Major Adverse Cardiovascular Events (MACE) that had VerifyNow P2Y12 and VerifyNow Aspirin assays performed. HTPR was defined as P2Y12 reactivity unit (PRU) > 208 for clopidogrel and aspirin reaction units (ARU) > 550 for aspirin. Renal function was classified based on the estimated glomerular filtration rate (eGFR), and dipstick proteinuria was defined as ≥ 30 mg/dl of albumin detected on a spot analysis. All cause mortality, readmissions, and cardiac catheterizations were reviewed over 520 days. In patients on clopidogrel (n = 106), DP was associated with HTPR, independent of eGFR, diabetes mellitus, smoking or use of proton pump inhibitor (AOR = 4.76, p = 0.03). In patients with acute coronary syndromes, HTPR was associated with more cardiac catheterizations (p = 0.009) and readmissions (p = 0.032), but no differences in in-stent thrombosis or re-stenosis were noted in this cohort. In patients on aspirin (n = 155), no associations were seen between DP and HTPR. However, all cause mortality was significantly higher with HTPR in this group (p = 0.038). In this cohort, DP is an independent predictor of HTPR in patients on clopidogrel, but not aspirin, admitted to the hospital for MACE.

Late antibody-mediated rejection in renal allografts: outcome after conventional and novel therapies

BACKGROUND

Although several strategies for treating early antibody-mediated rejection (AMR) in kidney transplants have been investigated, evidence on treatment of late AMR manifesting after 6 months is sparse. In this single-center series, we present data on 23 consecutive patients treated for late AMR.

METHODS

Late AMR was diagnosed using Banff 2007 criteria along with presence of donor-specific antibodies (DSA) and acute rise in serum creatinine (SCr). Response to therapy was assessed by improvement in SCr, histologic improvement, and decline in DSA strength.

RESULTS

Overall, 17% (4/23) had documented nonadherence while 69% (16/23) had physician-recommended reduction in immunosuppression before AMR. Eighteen patients (78%) were treated with plasmapheresis or low-dose IVIg+rituximab; 11 (49%) with refractory AMR also received one to three cycles of bortezomib. While there was an improvement (P=0.02) in mean SCr (2.4 mg/dL) at the end of therapy compared with SCr at the time of diagnosis (2.9 mg/dL), this improvement was not sustained at most recent follow-up. Eleven (48%) patients had no histologic resolution on follow-up biopsy. Lack of histologic response was associated with older patients (odds ratio [OR]=3.17; P=0.04), presence of cytotoxic DSA at time of diagnosis (OR=200; P=0.04), and severe chronic vasculopathy (cv≥2) on index biopsy (OR=50; P=0.06).

CONCLUSIONS

A major setting in which late AMR occurred in our cohort was reduction or change in immunosuppression. Our data demonstrate an inadequate response of late AMR to current and novel (bortezomib) therapies. The benefits of therapy need to be counterweighed with potential adverse effects especially in older patients, large antibody loads, and chronic allograft vasculopathy.

Establishing equations to evaluate 24 hour urine protein excretion using routine urinalysis

AIM

It is necessary to screen people at high risk for proteinuria with an economical, reliable and convenient method. The aim of this study is to establish a new approach to predict 24 h urine protein (24 h UP) by routine laboratory assays.

METHODS

Five centres were included and a total of 4211 hospitalized patients were enrolled. All samples were assayed for dipstick protein (DSP), specific gravity (SG), 24 h UP and serum albumin (ALB) simultaneously. 4211 patients were randomly divided into two groups for establishing and testing the equations. Equations were built by multiple log-linear regressions.

RESULTS

(i) DSP is significantly correlated to 24 h UP in a logarithmic pattern; (ii) SG interprets 24 h UP for specific DSP; (iii) Equation 1 = 0.203 × 10(dummy-variable F)  × [100 (SG-1)](-0.470) ; and (iv) Equation 2 = 13.366 × 10(dummy-variable F)  × [100 (SG-1)](-0.547)  × [ALB (g/L)](-1.130) The dummy-variable F had a point-to-point accordance to DSP (detailed in text).

CONCLUSION

Combination of DSP and SG can interpret normal-range proteinuria well, and helped by ALB, their interpretation for macro proteinuria is much improved. It is dependable and economical for routine urinalysis to evaluate pathological proteinuria by equation.

Shorter bevacizumab infusions do not increase the incidence of proteinuria and hypertension

BACKGROUND

A previous study has shown that shorter bevacizumab infusions (0.5 mg/kg/min) can be safely administered without increasing the risk of infusion-related hypersensitivity reactions (HSRs). However, the risk of proteinuria and hypertension in patients receiving shorter infusions of bevacizumab is undetermined.

PATIENTS AND METHODS

This was a multicenter, prospective, observational study in patients receiving <10 mg/kg of bevacizumab infused over 0.5 mg/kg/min. Patients were observed until discontinuation of bevacizumab for progression of cancer or toxicity. The incidence of hypertension and proteinuria was compared with a prior cohort of patients who had received standard duration infusions of bevacizumab.

RESULTS

Sixty-three patients received a total of 392 doses of shorter bevacizumab infusions. Nineteen (30.2%) patients experienced proteinuria while receiving bevacizumab. Out of 19 patients, 13 had grade 1 and 6 had grade 2 proteinuria. None of the patients experienced grade 3 or 4 proteinuria. Hypertension was reported in 32 (50.8%) patients receiving bevacizumab. Twelve (19%) patients developed grade 3 or greater hypertension on bevacizumab. The incidence of proteinuria and hypertension was 38.3% and 56.6%, respectively, in patients (N = 120, 1347 infusions) receiving standard duration infusions of bevacizumab.

CONCLUSIONS

Shorter bevacizumab infusions (0.5 mg/kg/min) do not increase the risk of proteinuria and hypertension.

Long-term management of patients with metastatic renal cell carcinoma on targeted agents

Therapy for patients with metastatic renal cell carcinoma is becoming increasingly effective. Sustained partial remissions, occasional complete responses and manageable quality of life are seen in a subset of individuals. As we face the prospect of generating an increasingly large number of patients requiring long-term management, the choice and timing of systemic therapy and surgical interventions is becoming increasingly important. In this article, we review the timing and type of cytoreductive nephrectomy, what to do for patients with oligometastatic disease and how to deal with complete responders. In addition, we summarize the major side effects experienced with the commonly used molecularly targeted agents, and provide guidance on how to maximize benefit from these agents while maintaining an acceptable quality of life for patients. As treatment efficacy improves, the optimal integration of systemic therapy, surgery and toxicity management will become a critical aspect of our care for patients with metastatic renal cell carcinoma.

Detection of urinary abnormalities in a community from northern Italy based on the World Kidney Day screening program

BACKGROUND

Chronic kidney disease (CKD) is a worldwide health problem, and promotion of the World Kidney Day has improved general population education and awareness of renal illnesses aimed at ameliorating disease prevention. The Kidney Day was also an opportunity for us to investigate risk factors for CKD in an Italian population.

PATIENTS AND METHODS

A total of 1,341 subjects from the general population living in the area of Ferrara, a town in the northeast of Italy, aged 50-70 years, were investigated. From each participant age, sex, smoking status, current antihypertensive medications, hypercholesterolemic and diabetic status, body mass index (BMI), waist circumference and blood pressure (BP) were obtained. All subjects underwent dipstick urinalysis for the evaluation of proteinuria, hematuria and leukocyturia.

RESULTS

Fifteen percent of patients were diabetics, and 20% were smokers. Mean BMI was 26.9 ± 4.3 kg/m(2), mean systolic BP was 133.7 ± 18.7 mmHg and mean diastolic BP 78.1 ± 9.9 mmHg. A total of 828 participants were not taking any antihypertensive drugs. In 24% of subjects, we found proteinuria, in 18% hematuria and in 16% leukocyturia. Proteinuria was significantly associated with age and diabetes, hematuria was associated with age, female sex and smoking status, and leukocyturia was associated with age and female sex.

CONCLUSIONS

Urinary abnormalities are common in general population, and in many cases, various abnormalities overlap. These abnormalities could be associated with cardiovascular risk factors. We believe that our initiative, based on the experience of the World Kidney Day, could increase the awareness of general practitioners and general population of the risks of renal conditions.

Proteinuria versus albuminuria in chronic kidney disease

Chronic kidney disease (CKD) is defined according to a decrease in the glomerular filtration rate and kidney damage such as proteinuria or albuminuria. Dip-stick proteinuria is only sensitive to albumin and correlates poorly with quantitative 24 h proteinuria, the most commonly used measure in renoprotective randomized controlled clinical trials (RCT). The amount of proteinuria correlates with the efficacy of angiotensin-converting enzyme inhibitors in non-diabetics in RCT. Random urine protein to creatinine ratio (PCR) or albumin to creatinine ratio (ACR) correlates with 24 h urinary excretion. Dip-stick proteinuria correlates poorly with ACR, while PCR correlates reasonably well with ACR. Because of a high analytical variability, efforts are in progress to standardize ACR (but not PCR) measurement. There have been no studies on the direct comparison between proteinuria and albuminuria in terms of utilities (biomarker, surrogate end-point and cost-effectiveness). In this regard, both proteinuria and albuminuria are good biomarkers for cardiovascular events, renal events or mortality. However, there are limitations in RCT regarding the validity of proteinuria or albuminuria as a surrogate end-point. In contrast, measuring proteinuria or albuminuria followed by treatment with angiotensin inhibitors is cost-effective for diabetics, hypertension and aging. CKD guidelines differ in their opinions regarding the choice between ACR and PCR. Based on the current evidence, ACR might be recommended for the diabetics and PCR for the non-diabetics.

Intricacies of bevacizumab-induced toxicities and their management

OBJECTIVE

To review the serious and common toxicities of bevacizumab and describe their incidence, risk factors, presentation, pathophysiology, and management.

DATA SOURCES

Literature for this review article was collected from PubMed, MEDLINE, and the proceedings of the American Society of Clinical Oncology (2000-November 2008). The key terms used in the search were: bevacizumab, vascular endothelial growth factor, angiogenesis inhibitors, toxicity, toxicity management, and adverse event.

STUDY SELECTION AND DATA EXTRACTION

Review articles, preclinical studies, and all published Phase 1-3 clinical trials were reviewed. The references listed in identified articles were examined for additional publications.

DATA SYNTHESIS

The biomedical literature from 2000 to 2008 confirms that bevacizumab carries serious and potentially life-threatening toxicity risks and emphasizes the importance of early recognition, continuous monitoring, and prompt management of these toxicities. Such toxicities include hemorrhage/bleeding, wound healing complications, gastrointestinal perforation, arterial thromboembolism, congestive heart failure, hypertension, proteinuria/nephrotic syndrome, infusion-related hypersensitivity reactions, and reversible posterior leukoencephalopathy syndrome. Patients at the highest risk for these toxicities are individuals with a history of hypertension, thromboembolism, bleeding, cardiovascular disease, or preexisting proteinuria, as these conditions may be exacerbated by bevacizumab use. Additionally, particular tumor types correlate with risk for individual toxicities; for example, patients with squamous non-small-cell lung cancer or rectal cancer have a higher risk of bleeding, those with renal cell carcinoma have a higher proteinuria risk, and patients with colorectal cancer have a higher risk of gastrointestinal perforation. Further investigation is warranted to develop effective management strategies for these toxicities.

CONCLUSIONS

As bevacizumab is becoming widely used in general oncology practice, it is important to understand the toxicities that can arise and to develop practice guidelines for their management.

Complement factor H and hemicentin-1 in age-related macular degeneration and renal phenotypes

In this study, we investigated the associations of complement factor H (CFH) and hemicentin-1 (HMCN1) with age-related macular degeneration (AMD) and renal function. Three scales, measuring the course of AMD and drusen development, were examined in two samples: the Family Age-Related Macular degeneration Study (FARMS), consisting of families ascertained through a single individual with severe AMD, and an unascertained population-based family cohort, the Beaver Dam Eye Study (BDES), which was also used to assess longitudinal changes in AMD and associations with renal function. Associations were performed by a regression accounting for known risk factors as well as familial and sibling effects. Strong evidence of the association of rs1061170 (Y402H) variation with AMD was confirmed (P = 9.15 x 10(-5) in BDES, P = 0.016 in FARMS). This association was observed in multiple AMD scales, suggesting that its role is not phenotype-specific. Polymorphisms in both CFH and HMCN1 appeared to influence the longitudinal rate of change of AMD. The rs1061170 polymorphism was also associated with a reduction in estimated glomerular filtration rate (eGFR) (P = 0.046). Another CFH polymorphism, rs800292, was similarly associated with eGFR [beta = -0.90 (P = 0.022)]. Associations between rs743137 (P = 0.05) and rs680638 (P = 0.022) in HMCN1 with calculated creatinine clearance progression were also observed. Both genes appear to play a role in both AMD and renal pathophysiology. These findings support evidence for common pathways influencing ocular and renal function and suggest that further work is required on their common determinants.

Essentials of laboratory medicine for the nephrology clinician

The purpose of this review is to compile and bring to the attention of the pediatric nephrology community various aspects of laboratory medicine pertinent to nephrology. The review addresses different aspects in laboratory medicine that should be taken into account during interpretation of a test result, such as methodological and analytical issues, statistical considerations and the biological interpretation of a test result in the context of the clinical setting. An understanding of the considerations and limitations in laboratory medicine will be helpful to the pediatric nephrologist when ordering and interpreting biochemical tests.

Antiproteinuric effect of oral paricalcitol in chronic kidney disease

BACKGROUND

Proteinuria is a marker of cardiovascular and renal disease in patients with chronic kidney disease (CKD), and reduction in proteinuria has been associated with improved cardiovascular and renal outcomes. While active vitamin D and its analogs have been shown to have renal protective effects in animals, these hormones have not been shown to reduce proteinuria in CKD patients.

METHODS

In three double-blind, randomized, placebo-controlled studies to evaluate the safety and efficacy of oral paricalcitol, 220 CKD stage 3 and 4 patients with secondary hyperparathyroidism (SHPT) were randomized to oral paricalcitol (N= 107, mean dose 9.5 microg/week) or placebo (N= 113) and followed for up to 24 weeks. In conjunction with other safety measures, proteinuria was measured by dipstick and read by an automated reader at the beginning and end of trial. We subsequently analyzed the dipstick data to evaluate the effect of paricalcitol on proteinuria.

RESULTS

At baseline, proteinuria was present in 57 patients randomized to oral paricalcitol and 61 patients randomized to placebo (NS). At the final visit, 29/57 (51%) of the paricalcitol patients compared to 15/61 (25%) placebo patients had reduction in proteinuria, P= 0.004 (odds for reduction in proteinuria 3.2 times greater for paricalcitol patients, 95% CI 1.5-6.9). For the patients who had both proteinuria at baseline and parathyroid hormone (PTH) suppression (end point defined as 2 consecutive > or =30% decreases in iPTH from baseline), 27/51 (53%) patients had a reduction in the proteinuria in the paricalcitol group and 0/7 (0%) had a reduction in proteinuria in the placebo group. Reduction of proteinuria favored patients on paricalcitol, regardless of age, sex, race, diabetes mellitus, hypertension, or use of therapies to block the renin-angiotensin-aldosterone system (RAAS).

CONCLUSION

Our results demonstrate that the reduction in proteinuria was associated with paricalcitol treatment, and the reduction in proteinuria was independent of concomitant use of agents that block the RAAS. Paricalcitol as a potential pharmacologic means of reducing proteinuria in CKD patients warrants further investigation.