Use of protein:creatinine ratio measurements on random urine samples for prediction of significant proteinuria: a systematic review

Glucometabolic characteristics and higher vascular complication risk in Korean patients with type 2 diabetes with non-albumin proteinuria

OBJECTIVE

We investigated the clinical relevance of non-albumin proteinuria (NAP) in Korean patients with type 2 diabetes (T2D).

RESEARCH DESIGN AND METHODS

We enrolled 883 T2D patients who had both their urinary albumin-to-creatinine ratio (uACR) and protein-to-creatinine ratio (uPCR) measured. We classified the patients into non-proteinuria (NP; uPCR <150 mg/g and uACR <30 mg/g), isolated NAP (iNAP; uPCR ≥150 mg/g and uACR <30 mg/g), and albuminuria (uACR ≥30 mg/g) groups. The associations between uPCR, uACR, and several indices of glucose metabolism were investigated.

RESULTS

The glucometabolic pathophysiology of iNAP (96 [10.9%]) group was more associated with a decrease in homeostatic model assessment (HOMA)-beta value (aOR 1.89 [95% CI, 1.21-2,96]) than with an increase in HOMA-insulin resistance (aOR 1.29 [95% CI, 0.83-2.01]). uPCR ≥150 mg/g was also found to have more consistent and stronger association with vascular complications than uACR ≥30 mg/g (aOR 1.44 [95% CI, 1.03-2.02] vs. 1.26 [95% CI, 0.89-1.79]).

CONCLUSIONS

The nephropathy of iNAP may be mainly attributed to decreased beta cell function. Furthermore, uPCR might be a more sensitive urinary biomarker than uACR for the detection of vascular complications in T2D patients.

Switching from entecavir to tenofovir alafenamide versus maintaining entecavir for chronic hepatitis B

Tenofovir alafenamide (TAF) is a newly developed prodrug of tenofovir (TFV). We divided 48 chronic hepatitis B patients who had taken entecavir (ETV) for ≥2 years into two groups: the ETV continuation (n = 24) and the TAF switching (n = 24) groups, and compared the antiviral effects and safety until 48 weeks after the start of the study. There were no significant differences in the alterations in the serum levels of HBs antigen (HBsAg) level between the ETV continuation and the TAF switching groups at 24 or 48 weeks. We also examined the effect of baseline HBsAg level on the decrease of HBsAg during the treatment; in the TAF switching group, the decrease of HBsAg level at 48 weeks was more significant in patients with low baseline HBsAg (<800 IU/mL) than those with high baseline HBsAg ( >800 IU/mL) (change of HBsAg; - 0.029 vs - 0.132 for high and low baseline HBsAg, respectively, P = .007). Also, the effect on renal function was found to be comparable between the TAF switch group and the ETV continuation group. In this study, switching from ETV to TAF may represent higher efficacy for a decrease of HBsAg than a continuation of ETV among the patients with low baseline HBsAg level.

Prevention of lipopolysaccharide-induced CD11b+ immune cell infiltration in the kidney: role of AT2 receptors

Immune cell infiltration plays a central role in mediating endotoxemic acute kidney injury (AKI). Recently, we have reported the anti-inflammatory and reno-protective role of angiotensin-II type-2 receptor (AT₂R) activation under chronic low-grade inflammatory condition in the obese Zucker rat model. However, the role of AT₂R activation in preventing lipopolysaccharide (LPS)-induced early infiltration of immune cells, inflammation and AKI is not known. Mice were treated with AT₂R agonist C21 (0.3 mg/kg), with and without AT₂R antagonist PD123319 (5 mg/kg) prior to or concurrently with LPS (5 mg/kg) challenge. Prior-treatment with C21, but not concurrent treatment, significantly prevented the LPS-induced renal infiltration of CD11b⁺ immune cells, increase in the levels of circulating and/or renal chemotactic cytokines, particularly interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) and markers of renal dysfunction (blood urea nitrogen and albuminuria), while preserving anti-inflammatory interleukin-10 (IL-10) production. Moreover, C21 treatment in the absence of LPS increased renal and circulating IL-10 levels. To investigate the role of IL-10 in a cross-talk between epithelial cells and monocytes, we performed in vitro conditioned media (CM) studies in human kidney proximal tubular epithelial (HK-2) cells and macrophages (differentiated human monocytes, THP-1 cells). These studies revealed that the conditioned-media derived from the C21-treated HK-2 cells reduced LPS-induced THP-1 tumor necrosis factor-α (TNF-α) production via IL-10 originating from HK-2 cells. Our findings suggest that prior activation of AT₂R is prophylactic in preventing LPS-induced renal immune cell infiltration and dysfunction, possibly via IL-10 pathway.

Clinical features and outcomes of kidney transplant recipients with focal segmental glomerulosclerosis recurrence

AIM

Focal segmental glomerulosclerosis recurs in up to 30% and up to 80% of adult and pediatric kidney transplant recipients, respectively. There is no standard of care treatment. The purpose of this study was to evaluate clinical characteristics, treatments and outcomes of patients with focal segmental glomerulosclerosis recurrence (FSGSr).

METHODS

This was a retrospective single-center cohort study including FSGSr patients treated with plasmapheresis (PP) and combinations of high dose steroids, cyclosporine and rituximab.

RESULTS

Among 61 patients included in this analysis the median time to diagnosis was 19 days. The incidence of first biopsy-confirmed FSGSr was 18% reaching 52.4% with follow-up biopsies. During PP treatment 54% of the patients developed infectious complications. PP was discontinued in 37% of patients due to treatment failure (no remission or graft loss) and in 26% due to an adverse event. All patients who discontinued PP due to adverse event did not show clinical response or lost the allograft. The incidence of acute rejection was 34.4%. The incidences of partial and complete remissions were 16.4% and 27.8%, respectively. Overall 6-years patient and graft survivals were 90.7% and 64.5%, respectively.

CONCLUSION

This analysis confirms the low, variable and unpredictable rate of FSGSr remission, inconsistencies among available therapeutic options and its high rate of adverse events, and the negative impact on graft survival.

Value of Cystatin C-Based e-GFR Measurements to Predict Long-Term Tenofovir Nephrotoxicity in Patients With Hepatitis B

BACKGROUND

Cystatin C is a genuine marker for detecting minor reductions in estimated glomerular filtration rate (e-GFR).

STUDY QUESTION

We aimed to investigate the efficiency of cystatin C levels in predicting nephrotoxicity due to antiviral therapy in patients with chronic hepatitis B virus infection.

STUDY DESIGN

Seventy-six naive hepatitis B virus patients and 44 controls were enrolled in this prospective cohort study.

MEASURES AND OUTCOMES

Serum cystatin C, phosphate and creatinine levels, and urinary albumin/creatinine ratios of all patients were measured at baseline, 3rd, 12th, and 24th months. Nephrotoxicity was determined according to the amount of change in creatinine level at the fourth year of treatment compared with baseline ([INCREMENT]Cr0-4).

RESULTS

Mean age was 36.1 ± 9.2 years and 40 (52.2%) of patients were women. There was no significant difference between baseline values of tenofovir disoproxil fumarate and entecavir groups. Although the creatinine level at the fourth year of treatment was statistically nonsignificant compared with baseline in the entecavir group, it was significantly higher in the fourth year of tenofovir treatment compared with baseline (0.95 ± 0.27 mg/dL vs. 0.76 ± 0.16 mg/dL, P = 0.002). While the increase in [INCREMENT]Cr0-4 was ≥0.2 mg/dL in 43.2% of patients in the tenofovir group, this rate was 18.8% in the entecavir group. Diagnostic accuracy in identifying decreased renal function as area under the curve (AUC) was high for baseline serum cystatin C level; furthermore, the highest AUC was calculated for cystatin C plus creatinine-based e-GFR equation (AUC: 0.81, P < 0.001).

CONCLUSIONS

Long-term tenofovir disoproxil fumarate nephrotoxicity can be predicted by serum cystatin C plus creatinine-based e-GFR measured before treatment.

Correlation between spot and 24h proteinuria: Derivation and validation of equation to estimate daily proteinuria

Daily urine protein (UP) loss is a cumbersome but important measurement to guide diagnosis and treatment of renal disease. Spot urine protein-creatinine ratio (UPCR) can been applied to estimate daily proteinuria. However, the correlations between spot and 24h proteinuria remain controversial. In this cross-sectional study, simultaneous collection of 24h and spot urines were performed from 1,039 (derivation cohort) and 204 CKD patients (validation cohort) of Chang Gung Memorial Hospital, from 2007 to 2017. The correlations between spot UPCR and 24h proteinuria were compared. The mean age of patients of derivation and validation cohort was 63 and 55 years and the mean estimated glomerular filtration rate was 62 ± 35 and 59 ± 36 mL/min/m², respectively. The correlation coefficient was 0.819 between UPCR and 24hUP. Prediction equation was derived as: Log₁₀24hUP (g) = 0.814 x Log₁₀UPCR (mg/mg) + 0.110 x Gender– 0.004 x Age + 0.004 x Body weight (kg) + 0.002 x CKD stage coefficient– 0.018, where CKD stage coefficient: CKD stage G1 = 1, G2 = 2, G3a = 3.1, G3b = 3.2, G4 = 4, G5 = 5. Correlation coefficient between measured and predicted 24hUP among derivation group and validation group is 0.866 and 0.915, respectively. However, the agreement of spot and daily estimates was less pronounced with proteinuria > 3g than lower values in Bland-Altman analysis. Spot UPCR can accurately predict 24hUP in patients with daily proteinuria below 3g. The development of this equation may facilitate estimation of 24hUP in the clinical practice.

Systemic pharmacokinetic/pharmacodynamic analysis of intravitreal aflibercept injection in patients with retinal diseases

Objective

Explore relationships between systemic exposure to intravitreal aflibercept injection (IAI) and systemic pharmacodynamic effects via post hoc analyses of clinical trials of IAI for neovascular age-related macular degeneration (nAMD) or diabetic macular oedema (DME).

Methods and analysis

Adults from VGFT-OD-0702.PK (n=6), VGFT-OD-0512 (n= 5), VIEW 2 (n=1204) and VIVID-DME (n=404) studies were included. Validated ELISAs were used to measure concentrations of free and bound aflibercept (reported as adjusted bound) in plasma at predefined time points in each study. Non-compartmental analysis of concentration-time data was obtained with dense sampling in VGFT-OD-0702.PK and VGFT-OD-0512. Sparse sampling was used in VIEW 2 and VIVID-DME. Blood pressure or intrarenal function changes were also investigated.

Results

Following intravitreal administration, free aflibercept plasma concentrations quickly decreased once maximum concentrations were achieved at 1-3 days postdose; pharmacologically inactive adjusted bound aflibercept concentrations increased over a longer period and reached plateau 7 days postdose. Ratios of free and adjusted bound aflibercept decreased over time. There were no meaningful changes in systolic/diastolic blood pressure over the duration of each study at all systemic aflibercept exposure levels. For all treatment arms in VIEW 2, there was no clinically relevant change in mean intrarenal function from baseline at week 52. Overall, incidence of systemic adverse events in VIEW 2 and VIVID-DME was low and consistent with the known safety profile of IAI.

Conclusion

IAI administration was not associated with systemic effects in patients with nAMD or DME as measured by blood pressure or intrarenal function, two known pharmacologically relevant effects of anti-vascular endothelial growth factor.

Proteinuria: Associated with poor outcome in patients with small cell lung cancer

Objective

Although proteinuria has been increasingly reported in lung cancers, especially small cell lung cancer (SCLC), its clinical impact in patients with SCLC remains unknown.

Materials and Methods

We analyzed patients with newly-diagnosed SCLC confirmed by clinical, radiological, and pathological features over a 7-year period. Pretreatment proteinuria was assessed by quantitative analysis of 24-h urine before receiving chemotherapy. The demographic, laboratory characteristics and its impact on survival outcome were evaluated.

Results

There were 140 SCLC patients with the mean age of 70.2 years, extensive stage (89.3%), and male predominance (81.4%). Significant proteinuria (>300 mg/day) occurred in 17.4% (24/140) patients. Patients with proteinuria had significant higher serum blood urea nitrogen, lower total calcium, total protein, albumin levels, and lower creatinine clearance (Ccr) (24-h Ccr). Daily protein excretion was negatively correlated with serum total protein, albumin, and Ccr. Using a multivariable Cox proportional hazard model, proteinuria (hazard ratio, 1.943, 95% confidence interval 1.148-3.259, P = 0.010), along with poor performance status and serum albumin, were independent risk factors of all-cause mortality. Proteinuria was also associated with poor survival status (6.08 vs. 11.88 months, P < 0.001), especially in those who had severe proteinuria (>2 g/day).

Conclusions

Proteinuria is not uncommon and associated with all-cause mortality in patients with SCLC.

Spot protein-creatinine ratio and spot albumin-creatinine ratio in the assessment of pre-eclampsia: a diagnostic accuracy study with decision-analytic model-based economic evaluation and acceptability analysis

BACKGROUND

The National Institute for Health and Care Excellence (NICE) guidelines highlighted the need for 'large, high-quality prospective studies comparing the various methods of measuring proteinuria in women with new-onset hypertensive disorders during pregnancy'.

OBJECTIVES

The primary objective was to evaluate quantitative assessments of spot protein-creatinine ratio (SPCR) and spot albumin-creatinine ratio (SACR) in predicting severe pre-eclampsia (PE) compared with 24-hour urine protein measurement. The secondary objectives were to investigate interlaboratory assay variation, to evaluate SPCR and SACR thresholds in predicting adverse maternal and fetal outcomes and to assess the cost-effectiveness of these models.

DESIGN

This was a prospective diagnostic accuracy cohort study, with decision-analytic modelling and a cost-effectiveness analysis.

SETTING

The setting was 36 obstetric units in England, UK.

PARTICIPANTS

Pregnant women (aged ≥ 16 years), who were at > 20 weeks' gestation with confirmed gestational hypertension and trace or more proteinuria on an automated dipstick urinalysis.

INTERVENTIONS

Women provided a spot urine sample for protein analysis (the recruitment sample) and were asked to collect a 24-hour urine sample, which was stored for secondary analysis. A further spot sample of urine was taken immediately before delivery.

MAIN OUTCOME MEASURES

Outcome data were collected from hospital records. There were four index tests on a spot sample of urine: (1) SPCR test (conducted at the local laboratory); (2) SPCR test [conducted at the central laboratory using the benzethonium chloride (BZC) assay]; (3) SPCR test [conducted at the central laboratory using the pyrogallol red (PGR) assay]; and (4) SACR test (conducted at the central laboratory using an automated chemistry analyser). The comparator tests on 24-hour urine collection were a central test using the BZC assay and a central test using the PGR assay. The primary reference standard was the NICE definition of severe PE. Secondary reference standards were a clinician diagnosis of severe PE, which is defined as treatment with magnesium sulphate or with severe PE protocol; adverse perinatal outcome; one or more of perinatal or infant mortality, bronchopulmonary dysplasia, necrotising enterocolitis or grade III/IV intraventricular haemorrhage; and economic cost and outcomes. Health service data on service use and costs followed published economic models.

RESULTS

In total, 959 women were available for primary analysis and 417 of them had severe PE. The diagnostic accuracy of the four assays on spot urine samples against the reference standards was similar. The three SPCR tests had sensitivities in excess of 90% at prespecified thresholds, with poor specificities and negative likelihood ratios of ≥ 0.1. The SACR test had a significantly higher sensitivity of 99% (confidence interval 98% to 100%) and lower specificity. Receiver operating characteristic (ROC) curves were similar (area under ROC curve between 0.87 and 0.89); the area under the central laboratory's SACR curve was significantly higher (p = 0.004). The central laboratory's SACR test was the most cost-effective option, generating an additional 0.03 quality-adjusted life-years at an additional cost of £45.07 compared with the local laboratory's SPCR test. The probabilistic analysis showed it to have a 100% probability of being cost-effective at the standard willingness-to-pay threshold recommended by NICE.

LIMITATIONS

Implementation of NICE guidelines has led to an increased intervention rate in the study population that affected recruitment rates and led to revised sample size calculations.

CONCLUSIONS

Evidence from this clinical study does not support the recommendation of 24-hour urine sample collection in hypertensive pregnant women. The SACR test had better diagnostic performance when predicting severe pre-eclampsia. All four tests could potentially be used as rule-out tests for the NICE definition of severe PE.

FUTURE WORK

Testing SACR at a threshold of 8 mg/mmol should be studied as a 'rule-out' test of proteinuria.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN82607486.

FUNDING

This project was funded by the National Institute Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 61. See the NIHR Journals Library website for further project information.

Boldine Improves Kidney Damage in the Goldblatt 2K1C Model Avoiding the Increase in TGF-β

Boldine, a major aporphine alkaloid found in the Chilean boldo tree, is a potent antioxidant. Oxidative stress plays a detrimental role in the pathogenesis of kidney damage in renovascular hypertension (RVH). The activation of the renin-angiotensin system (RAS) is crucial to the development and progression of hypertensive renal damage and TGF-β is closely associated with the activation of RAS. In the present study, we assessed the effect of boldine on the progression of kidney disease using the 2K1C hypertension model and identifying mediators in the RAS, such as TGF-β, that could be modulated by this alkaloid. Toward this hypothesis, rats (n = 5/group) were treated with boldine (50 mg/kg/day, gavage) for six weeks after 2K1C surgery (pressure ≥ 180 mmHg). Kidney function was evaluated by measuring of proteinuria/creatininuria ratio (U prot/U Crea), oxidative stress (OS) by measuring thiobarbituric acid reactive substances (TBARS). The evolution of systolic blood pressure (SBP) was followed weekly. Alpha-smooth muscle actin (α-SMA) and Col III were used as markers of kidney damage; ED-1 and osteopontin (OPN) were used as markers of inflammation. We also explored the effect in RAS mediators, such as ACE-1 and TGF-β. Boldine treatment reduced the UProt/UCrea ratio, plasma TBARS, and slightly reduced SBP in 2K1C hypertensive rats, producing no effect in control animals. In 2K1C rats treated with boldine the levels of α-SMA, Col III, ED-1, and OPN were lower when compared to 2K1C rats. Boldine prevented the increase in ACE-1 and TGF-β in 2K1C rats, suggesting that boldine reduces kidney damage. These results suggest that boldine could potentially be used as a nutraceutic.

Urolithiasis is prevalent and associated with reduced bone mineral density in β-thalassaemia major

Asymptomatic urolithiasis is common and of mixed composition in patients with β-thalassaemia major. Twenty-seven subjects were imaged using dual-energy computer tomography to determine the presence and composition of urolithiasis. The prevalence of urolithiasis was 59% and affected patients generally had multiple stones, often with more than one component: struvite (33%), calcium oxalate (31%) and cystine (22%). Hypercalciuria was present in 78% of subjects and calcium-containing urolithiasis was associated with reduced femoral neck Z scores.

Spot Urine Protein-to-Creatinine Ratio to Predict the Magnitude of 24-Hour Total Proteinuria in Preeclampsia of Varying Severity

OBJECTIVE

The predictive value of spot urine protein-to-creatinine ratio (PCR) for estimating total 24-hour proteinuria in severe preeclampsia is unclear. This study aimed to assess the diagnostic accuracy of spot urine PCR for ascertaining the magnitude of proteinuria in women with preeclampsia of varying severity.

METHODS

A total of 205 patients with prediagnosed preeclampsia were included in this prospective cohort study. Patients were allocated into one of the three groups categorized by severity of disease, as follows: gestational hypertension, group 1 (n = 41); preeclampsia, group 2 (n = 88); and severe preeclampsia, group 3 (n = 76). We assessed the spot urine PCRs to determine significant proteinuria and the magnitude of proteinuria in these groups.

RESULTS

The spot urine PCR was 0.53, with 81% sensitivity and 93% specificity to detect significant proteinuria. A significant correlation was found between PCR and 24-hour total proteinuria in group 1 (r = 0.473, P = 0.002). There were also significant correlations in group 2 (r = 0.814, P < 0.001) and group 3 (r = 0.912, P < 0.001). The established formula using spot urine PCR to estimate 24-hour total proteinuria in severe preeclampsia was Y = 832.02X + 378.74 mg (r² = 0.8304).

CONCLUSION

Although 24-hour urine collection remains a merely reliable test to determine the degree of total proteinuria, our findings suggest that it is likely to assess the magnitude of proteinuria by the spot urine PCR, especially in severe preeclampsia.

CLINICAL TRIAL REGISTRATION

www.clinicaltrials.govNCT01623791.

The prevalence of albuminuria among diabetic patients in a primary care setting in Singapore

INTRODUCTION

Microalbuminuria is an early sign of kidney damage. The prevalence of microalbuminuria in Singapore has been reported to be 36.0%-48.5%. However, the prevalence of microalbuminuria reported in these studies was determined with one urine sample using a qualitative urine test. The aim of this study was to determine the prevalence of micro- and macroalbuminuria using a more stringent criterion of two positive quantitative urine albumin-creatinine ratio (ACR) tests.

METHODS

We conducted a cross-sectional study of patients with type 2 diabetes mellitus (T2DM) who were followed up at a primary care clinic in Singapore. Patients were diagnosed to have albuminuria if they had two positive ACR tests within a seven-month period.

RESULTS

A total of 786 patients with T2DM met the study's inclusion criteria. 55.7% were already on an angiotensin-converting enzyme inhibitor (ACEI) and/or angiotensin receptor blocker (ARB). The prevalence rates of micro- and macroalbuminuria were 14.2% and 5.7%, respectively. Patients with albuminuria were more likely to have hypertension (odds ratio [OR] 3.47, 95% confidence interval [CI] 1.55-7.80). Diabetics with poorer diabetic control (OR 1.88, 95% CI 1.26-2.79), and higher systolic (OR 1.69, 95% CI 1.14-2.49) and diastolic (OR 1.96, 95% CI, 1.20 to 3.22) blood pressures were more likely to have albuminuria.

CONCLUSION

In the present study, the prevalence of microalbuminuria is significantly lower than that previously reported in Singapore. The presence of hypertension, poor diabetic control and suboptimal blood pressure control are possible risk factors for albuminuria in patients with T2DM.

High-Normal Estimated Glomerular Filtration Rate in Early-Onset Preeclamptic Women 10 Years Postpartum

Women with a history of preeclampsia have a 5- to 12-fold increased risk to develop end-stage kidney disease. Previous observations in small cohorts suggest that former preeclamptic (fPE) women have subtle abnormalities in renal hemodynamics and renal function, which might predispose them to renal failure in later life. In this study, we analyzed renal function in a cross-sectional cohort consisting of former early-onset preeclamptic (fPE, n=339) and former healthy pregnant women (fHP, n=332), overall with a mean age of 39 years at 10 years postpartum. Estimated glomerular filtration rate (eGFR), assessed by the modification of diet in renal disease (MDRD) and chronic kidney disease–epidemiology (CKD-epi) equations, and urinary protein:creatinine ratios were assessed 10 years postpartum. Median MDRD and CKD-epi eGFR did not significantly differ between fHP and fPE groups, whereas a comparison of distribution of eGFR revealed a shift toward a high-normal MDRD eGFR in the fPE group (χ 2 , P =0.02) with the same trend for CKD-epi eGFR (χ 2 , P =0.18). The odds ratio for fPE women having MDRD eGFR >110 mL/min per 1.73 m 2 was 1.6 (1.1–2.4). In addition, the median urinary protein:creatinine ratio was slightly higher in fPE (8.5 versus 7.1 mg/mmol; P <0.01) and correlated positively with both MDRD and CKD-epi eGFR in fPE women. No increased incidence of CKD in fPE women was observed. In conclusion, we demonstrate subtle changes in renal function in former early-onset preeclamptic women 10 years postpartum, characterized by a high-normal eGFR and a slightly higher protein excretion. Whether these subtle differences predispose to or predict long-term renal function loss in fPE women remains to be investigated.

Clinical Trial Registration—

URL: http://www.trialregister.nl . Unique identifier: NTR2668.

The efficacy of semi-quantitative urine protein-to-creatinine (P/C) ratio for the detection of significant proteinuria in urine specimens in health screening settings

Background

Urine protein detection could be underestimated using the conventional dipstick method because of variations in urine aliquots. This study aimed to assess the efficacy of the semi-quantitative urine protein-to-creatinine (P/C) ratio compared with other laboratory methods.

Methods

Random urine samples were requested from patients undergoing chronic kidney disease screening. Significant proteinuria was determined by the quantitative P/C ratio of at least 150 mg protein/g creatinine. The semi-quantitative P/C ratio, dipstick protein and quantitative protein concentrations were compared and analyzed.

Results

In the 2932 urine aliquots, 156 (5.3 %) urine samples were considered as diluted and 60 (39.2 %) were found as significant proteinuria. The semi-quantitative P/C ratio testing had the best sensitivity (70.0 %) and specificity (95.9 %) as well as the lowest underestimation rate (0.37 %) when compared to other laboratory methods in the study. In the semi-quantitative P/C ratio test, 19 (12.2 %) had positive, 52 (33.3 %) had diluted, and 85 (54.5 %) had negative results. Of those with positive results, 7 (36.8 %) were positive detected by traditional dipstick urine protein test, and 9 (47.4 %) were positive detected by quantitative urine protein test. Additionally, of those with diluted results, 25 (48.1 %) had significant proteinuria, and all were assigned as no significant proteinuria by both tests.

Conclusions

The semi-quantitative urine P/C ratio is clinically applicable based on its better sensitivity and screening ability for significant proteinuria than other laboratory methods, particularly in diluted urine samples. To establish an effective strategy for CKD prevention, urine protein screening with semi-quantitative P/C ratio could be considered.

The relatively poor correlation between random and 24-hour urine protein excretion in patients with biopsy-proven glomerular diseases

Random urine protein creatinine ratios are used to estimate 24-hour urine protein excretion, which is considered a diagnostic gold standard. However, few studies are available of the sensitivity and specificity of this estimation in patients with glomerular proteinuria. To clarify this, we measured the urine protein and creatinine centrally in random and 24-hour urine collections at biopsy and longitudinally every 6 months in individuals participating in the Nephrotic Syndrome Study Network (NEPTUNE) cohort with glomerular disease. In the initial developmental cohort, 302 patients had same day random and 24-hour samples with a total of 827 paired measurements across all visits. The protein excretion (g/day) was higher in adult than pediatric patients. The correlation between the random urine protein creatinine ratio and 24-hour urine protein excretion was moderate in both groups (r of 0.60 and 0.67, respectively). However, the log₁₀ transformation of values strengthened correlations in both groups (r of 0.85 and 0.82, respectively). Associations were moderately stronger among obese patients. Prediction equations were developed and validated in 232 unique cases from NEPTUNE (R² of 0.65). Thus, in patients with glomerular disease and proteinuria, the urine protein creatinine ratio correlates only moderately with 24-hour urine protein excretion. However an estimating equation was developed to derive 24-hour urine protein excretion from random urine protein creatinine ratio values with improved precision. The long-term prognostic value of log₁₀-transformed random protein creatinine ratios values requires future study.

Measures of Urinary Protein and Albumin in the Prediction of Progression of IgA Nephropathy

BACKGROUND AND OBJECTIVES

Proteinuria is an independent predictor for IgA nephropathy (IgAN) progression. Urine albumin-to-creatinine ratio (ACR), protein-to-creatinine ratio, and 24-hour urine protein excretion (UPE) are widely used for proteinuria evaluation in clinical practice. Here, we evaluated the association of these measurements with clinical and histologic findings of IgAN and explored which was the best predictor of IgAN prognosis.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Patients with IgAN were followed up for ≥12 months, were diagnosed between 2003 and 2012, and had urine samples available (438 patients). Spot urine ACR, protein-to-creatinine ratio, and 24-hour UPE at the time of renal biopsy were measured on a Hitachi Automatic Biochemical Analyzer 7180 (Hitachi, Yokohama, Japan).

RESULTS

In our patients, ACR, protein-to-creatinine ratio, and 24-hour UPE were highly correlated (correlation coefficients: 0.71-0.87). They showed good relationships with acknowledged markers reflecting IgAN severity, including eGFR, hypertension, and the biopsy parameter (Oxford severity of tubular atrophy/interstitial fibrosis parameter). However, only ACR presented with positive association with the Oxford segmental glomerulosclerosis/adhesion parameter and extracapillary proliferation lesions. The follow-up time was 37.0 (22.0-58.0) months, with the last follow-up on April 18, 2014. In total, 124 patients reached the composite end point (30% eGFR decline, ESRD, or death). In univariate survival analysis, ACR consistently had better performance than protein-to-creatinine ratio and 24-hour UPE as represented by higher area under the curve using time-dependent survival analysis. When adjusted for well known risk factors for IgAN progression, ACR was most significantly associated with the composite end point (hazard ratio, 1.56 per 1-SD change of standard normalized square root-transformed ACR; 95% confidence interval, 1.29 to 1.89; P<0.001). Compared with protein-to-creatinine ratio and 24-hour UPE, addition of ACR to traditional risk factors resulted in more improvement in the predictive ability of IgAN progression (c statistic: ACR=0.70; protein-to-creatinine ratio =0.68; 24-hour UPE =0.69; Akaike information criterion: ACR=1217.85; protein-to-creatinine ratio =1229.28; 24-hour UPE =1234.96; P<0.001).

CONCLUSIONS

In IgAN, ACR, protein-to-creatinine ratio, and 24-hour UPE had comparable association with severe clinical and histologic findings. Compared with protein-to-creatinine ratio and 24-hour UPE, ACR showed slightly better performance in predicting IgAN progression.

Urinary Protein Creatinine Ratio in Normal Zero to Three-Day-Old Indian Neonates

INTRODUCTION

Early neonates (1-7-day-old) may develop acute kidney injury or acute renal failure due to functional (pre-renal, may be caused by decreased renal perfusion), intrinsic (renal, may be caused by acute insult), or obstructive (due to anatomic urinary tract obstruction) causes. Urinary protein estimation is important for diagnosis, follow-up and prognosis of disease. The Protein Creatinine Ratio (PCR) has been successfully used to establish proteinuria in different types of patients.

AIM

This study was undertaken to establish normal PCR range in neonates, to rule out abnormal protein excretion in sick neonates.

MATERIALS AND METHODS

A total of 37 normal early neonates of age 0-3 days were enrolled for this study. Random spot urine samples were collected in paediatric urine bags for protein and creatinine estimation.

RESULTS

The urinary PCR varied between 0.1-0.8. The range of PCR values obtained was greater in 0-1 day old infants, compared to infants older than one day. Changes in PCR values were due to variations in the creatinine excretion.

CONCLUSION

Urinary PCR values ≤ 0.8 indicate normal protein excretion. However, reference intervals of PCR should be established for narrow age groups in case of early neonates, e.g. 0-6h, 6-12h, 12-24h, 24-72h old babies.

Deferasirox at therapeutic doses is associated with dose-dependent hypercalciuria

Deferasirox is an oral iron chelator used widely in the treatment of thalassemia major and other transfusion-dependent hemoglobinopathies. Whilst initial long-term studies established the renal safety of deferasirox, there are now increasing reports of hypercalciuria and renal tubular dysfunction. In addition, urolithiasis with rapid loss of bone density in patients with β thalassemia major has been reported. We conducted a cross-sectional cohort study enrolling 152 adult patients comprising of β thalassemia major (81.5%), sickle cell disease (8%), thalassemia intermedia (2%), HbH disease (6.5%) and E/β thalassemia (2%). Cases were matched with normal control subjects on age, gender and serum creatinine. Iron chelator use was documented and urine calcium to creatinine ratios measured. At the time of analysis, 88.8% of patients were receiving deferasirox and 11.2% were on deferoxamine. Hypercalciuria was present in 91.9% of subjects on deferasirox in a positive dose-dependent relationship. This was not seen with subjects receiving deferoxamine. At a mean dose of 30.2±8.8mg/kg/day, deferasirox was associated with an almost 4 fold increase in urine calcium to creatinine ratio (UCa/Cr). Hypercalciuria was present at therapeutic doses of deferasirox in a dose-dependent manner and warrants further investigation and vigilance for osteoporosis, urolithiasis and other markers of renal dysfunction.

Diagnostic efficacy of random albumin creatinine ratio for detection of micro and macro-albuminuria in type 2 diabetes mellitus

OBJECTIVES

To compare a less cumbersome random albumin creatinine ratio (RACR) with 24-hour urinary albumin excretion (UAE) for detection of renal damage in patients with type 2 diabetes mellitus (T2DM).

METHODS

This retrospective study performed between March 2013 and June 2014 at the Department of Pathology, King Khalid University Hospital, Riyadh, Kingdom of Saudi Arabia included 122 patients (mean age 54 ± 15, 104 females and 18 males) with T2DM. Urine albumin levels of less than 30 mg/g was considered normal, from 30-300 mg/g considered as micro-albuminuria, and over 300 mg/g considered as macro-albuminuria.

RESULTS

Concordance between the 2 assays was observed in 114 (93.4%) samples. The sensitivity of RACR assay was 100%, specificity was 91.3% with a positive predictive value (PPV) of 95%, and a negative predictive value (NPV) of 100% in micro-albuminuria range. For macro-albuminuria, RACR had a sensitivity of 100%, specificity of 94.1% with PPV of 94% and NPV of 100%. Receiver operating characteristic (ROC) curves analysis cut-off values of 40 mg/g-300 mg/g for micro- and greater than 300 mg/g for macro-albuminuria revealed 100% sensitivity, 97.5% specificity, 95% PPV, and 100% NPV for micro-albuminuria, and 100% sensitivity, 94% specificity, 76% PPV, and 100% NPP for macro-albuminuria. The area under the curve for micro-albuminuria was 100% and 98.2% for macro-albuminuria.

CONCLUSION

Performance of RACR was comparable to 24 hour UAE assay particularly in excluding renal damage in T2DM.

Association between urine protein/creatinine ratio and cognitive dysfunction in Lewy body disorders

BACKGROUND

Impaired renal function and proteinuria have been associated with cognitive impairment and dementia. Chronic kidney disease is considered to be an independent risk factor for Lewy body spectrum disorders (LBD). However, few studies have mentioned an association between proteinuria and cognition in LBD. We investigated the relationship between proteinuria and cognitive dysfunction in patients with Parkinson's disease (PD) and dementia with Lewy bodies (DLB).

METHODS

Among 186 patients with LBD, 53 had PD-normal cognition (PD-NC), 76 had PD-mild cognitive impairment (PD-MCI), 43 had PD-dementia (PDD) and 14 had DLB. The urine protein/creatinine ratio was calculated using the spot urine test and brain magnetic resonance scans was obtained in all patients.

RESULTS

The urine protein/creatinine ratio was significantly higher in patients with PDD and DLB than in those with PD-MCI, PD-NC patients and healthy controls, and was correlated with white matter hyperintensities on magnetic resonance imaging. All abnormal neuropsychological test results were associated with increased urine protein/creatinine ratio. After controlling for age, education, symptom duration, diabetes mellitus, hypertension, and parkinsonian motor severity, the urine protein/creatinine ratio was significantly associated with decreased cognition.

CONCLUSION

The urine protein/creatinine ratio was associated with cognitive status in LBD. These finding suggests that increased protein excretion is associated with cognitive dysfunction in patients with LBD.

A New Gender-Specific Formula to Estimate 24-Hour Urine Protein from Protein to Creatinine Ratio

<b><i>Background:</i></b> The quantification of proteinuria with the protein to creatinine ratio (PCR) is influenced by the excretion of creatinine, which, in turn, varies according to muscle mass and hence, to gender. <b><i>Aims:</i></b> To assess the difference between urine PCR and 24-hour urine proteinuria in men and women and to provide a formula to overcome bias caused by gender. <b><i>Methods:</i></b> Four hundred and forty four CKD patients were randomly divided into 2 groups: 70% were used to develop the models, while the remaining 30% were reserved to validate the formula. Epidemiological data were analyzed with chi-square and Student's t tests. Association between 24-hour proteinuria and PCR was studied with Spearman coefficient in men and women separately. Multivariate analysis was used to find variables predictive of disagreement between the 24-hour urine protein and the PCR. Equations to predict 24-hour proteinuria from PCR for men and women were plotted and validated. <b><i>Results:</i></b> Disagreement between 24-hour proteinuria and PCR was more pronounced in men (2.16 and 1.64 g in mean, respectively) than in women (2.00 and 2.06 g in mean, respectively). Age and gender were independent predictors of disagreement. Gender-specific equations for predicting 24-hour proteinuria were: males: 24-hour proteinuria = 1.3350*exp^0.9108*^ln(PCR); females: 24-hour proteinuria = 1.0068*exp^0.9030*^ln(PCR). <b><i>Conclusions:</i></b> Estimation of proteinuria with the PCR improves accuracy if gender-specific equations are used. Use of the PCR without correction for gender leads to the underestimation of proteinuria in men and overestimation in women.

[Spot urinary protein to creatinine ratio: Which role in preeclampsia diagnosis?]

Preeclampsia remains a serious and feared complication of pregnancy. Its diagnosis is confirmed upon detection of hypertension and significant proteinuria starting from 20 weeks of gestation. The 24-hour urine collection is considered to be the gold standard test for quantitative diagnosis of proteinuria despite its downsides. Recent studies have brought into question its accuracy during pregnancy as complete samples are hard to get, but above all, as this time consuming procedure often delays treatment and may preclude optimal management. Several publications looked at the spot urinary protein to creatinine ratio (PCR) as a replacement to the 24-hour urine collection. Largely used outside pregnancy, this fast and less invasive test seems a compelling alternative. In this paper, data from previous meta-analysis and guidelines have been reviewed in an attempt to clarify the role of the PCR in clinical practice and elaborate an algorithm in case of suspicion of preeclampsia. Thus, this test seems a valid "rule-out test" when using the optimal threshold of 30mg/mmol. Higher values require a 24-hour urine collection for confirmation.

Decrease of glomerular filtration rate may be attributed to the microcirculation damage in renal artery stenosis

BACKGROUND

The decrease of glomerular filtration rate has been theoretically supposed to be the result of low perfusion in renal artery stenosis (RAS). But the gap between artery stenosis and the glomerular filtration ability is still unclear.

METHODS

Patients with selective renal artery angiogram were divided by the degree of renal artery narrowing, level of estimated glomerular filtration rate (eGFR), respectively. The different levels of eGFR, renal microcirculation markers, and RAS severity were compared with each other, to determine the relationships among them.

RESULTS

A total of 215 consecutive patients were enrolled in the prospective cohort study. Concentrations of microcirculation markers had no significant difference between RAS group (RAS ≥ 50%) and no RAS group (RAS < 50%) or did not change correspondingly to RAS severity. The value of eGFR in RAS group was lower than that in the no RAS group, but it did not decline parallel to the progressive severity of RAS. The microcirculation markers presented integral difference if grouped by different eGFR level with negative tendency, especially that plasma cystatin C (cysC) and urinary microalbumin to creatinine ratio (mACR) increased with the deterioration of eGFR, with strong (r = -0.713, P < 0.001) and moderate (r = -0.580, P < 0.001) correlations. In the subgroup analysis of severe RAS (RAS ≥ 80%), the levels of plasma cysC and urinary mACR demonstrated stronger negative associations with eGFR, (r = -0.827, P < 0.001) and (r = -0.672, P < 0.001) correlations, respectively.

CONCLUSIONS

Severity of RAS could not accurately predict the value of eGFR, whereas microcirculation impairment may substantially contribute to the glomerular filtration loss in patients with RAS.

Selective Targeting of a Disease-Related Conformational Isoform of Macrophage Migration Inhibitory Factor Ameliorates Inflammatory Conditions

Macrophage migration inhibitory factor (MIF), a proinflammatory cytokine and counterregulator of glucocorticoids, is a potential therapeutic target. MIF is markedly different from other cytokines because it is constitutively expressed, stored in the cytoplasm, and present in the circulation of healthy subjects. Thus, the concept of targeting MIF for therapeutic intervention is challenging because of the need to neutralize a ubiquitous protein. In this article, we report that MIF occurs in two redox-dependent conformational isoforms. We show that one of the two isoforms of MIF, that is, oxidized MIF (oxMIF), is specifically recognized by three mAbs directed against MIF. Surprisingly, oxMIF is selectively expressed in the plasma and on the cell surface of immune cells of patients with different inflammatory diseases. In patients with acute infections or chronic inflammation, oxMIF expression correlated with inflammatory flare-ups. In addition, anti-oxMIF mAbs alleviated disease severity in mouse models of acute and chronic enterocolitis and improved, in synergy with glucocorticoids, renal function in a rat model of crescentic glomerulonephritis. We conclude that oxMIF represents the disease-related isoform of MIF; oxMIF is therefore a new diagnostic marker for inflammation and a relevant target for anti-inflammatory therapy.

Urinalysis in children and adolescents

BACKGROUND

Urinalysis is the most commonly performed biochemical test in infancy and early childhood. The urine sample should be correctly obtained, age-specific aspects should be considered, and age-dependent reference values should be used.

METHOD

This review is based on a selective literature search in electronic databases, textbooks, and guidelines from Germany and abroad on the acquisition of urine samples and the performance of urinalysis in infancy and early childhood.

RESULTS

The timing and mode of acquisition of the urine sample affect the assessment of hematuria, proteinuria, leukocyturia, nitrituria, and the uropathogenic bacterial colony count in the urine culture. Dipstick tests can be used for targeted screening for these features. The test results should be interpreted together with the findings of urine microscopy, the medical history, and the physical examination. Proteinuria should be quantified and differentiated; both of these things can be done either from collected urine or (especially in infants and young children) from a spontaneously voided urine sample, by determination of the protein/creatinine quotient. Orthostatic proteinuria in an adolescent requires no further evaluation or treatment. Hematuria should be characterized as either glomerular or non-glomerular erythrocyturia. Asymptomatic, isolated microhematuria in childhood is not uncommon and often transient; in the absence of a family history, it usually does not require an extensive work-up. Proteinuria combined with hematuria should arouse the suspicion of glomerulonephritis.

CONCLUSION

Urinalysis in infancy and early childhood is a simple and informative diagnostic test as long as the urine sample has been obtained properly and the results are interpreted appropriately for this age group.

Urinary candidate biomarker discovery in a rat unilateral ureteral obstruction model

Urine has the potential to become a better source of biomarkers. Urinary proteins are affected by many factors; therefore, differentiating between the variables associated with any particular pathophysiological condition in clinical samples is challenging. To circumvent these problems, simpler systems, such as animal models, should be used to establish a direct relationship between disease progression and urine changes. In this study, a unilateral ureteral obstruction (UUO) model was used to observe tubular injury and the eventual development of renal fibrosis, as well as to identify differential urinary proteins in this process. Urine samples were collected from the residuary ureter linked to the kidney at 1 and 3 weeks after UUO. Five hundred proteins were identified and quantified by LC-MS/MS, out of which 7 and 19 significantly changed in the UUO 1- and 3-week groups, respectively, compared with the sham-operation group. Validation by western blot showed increased levels of Alpha-actinin-1 and Moesin in the UUO 1-week group, indicating that they may serve as candidate biomarkers of renal tubular injury, and significantly increased levels of Vimentin, Annexin A1 and Clusterin in the UUO 3-week group, indicating that they may serve as candidate biomarkers of interstitial fibrosis.

Estimation of Daily Proteinuria in Patients with Amyloidosis by Using the Protein-To-Creatinine ratio in Random Urine Samples

Measurement of daily proteinuria in patients with amyloidosis is recommended at the time of diagnosis for assessing renal involvement, and for monitoring disease activity. Renal involvement is usually defined by proteinuria >500 mg/day. We evaluated the accuracy of the random urine protein-to-creatinine ratio (Pr/Cr) in predicting 24 hour proteinuria in patient with amyloidosis. We compared results of random urine Pr/Cr ratio and concomitant 24-hour urine collections in 44 patients with amyloidosis. We found a strong correlation (Spearman’s ρ=0.874) between the Pr/Cr ratio and the 24 hour urine protein excretion. For predicting renal involvement, the optimal cut-off point of the Pr/Cr ratio was 715 mg/g. The sensitivity and specificity for this point were 91.8% and 95.5%, respectively, and the area under the curve value was 97.4%. We conclude that the random urine Pr/Cr ratio could be useful in the screening of renal involvement in patients with amyloidosis. If validated in a prospective study, the random urine Pr/Cr ratio could replace the 24 hour urine collection for the assessment of daily proteinuria and presence of nephrotic syndrome in patients with amyloidosis.

Spot protein/creatinine ratio in preeclampsia as an alternative for 24-hour urine protein

BACKGROUND

Proteinuria is a major component of preeclampsia. Urine protein measurement after 24-hour urine collection is the traditional standard method for the detection of proteinuria. It is time-consuming. As an alternative, random spot sampling for a urine protein to creatinine (P/C) ratio has been investigated.

AIMS

The aim of the study was to determine the diagnostic accuracy of the protein to creatinine ratio (P/C) compared with 24-hour urine collection for the detection of remarkable proteinuria and to evaluate the P/C ratio for different proteinuria ranges in patients with preeclampsia.

STUDY DESIGN

Case-control study.

METHODS

Two hundred and eleven pregnant women who met the criteria of preeclampsia comprised the study group and fifty three pregnant women were taken as the control group. Spot urine specimens for measuring P/C ratio were obtained taken immediately before 24-hour urine collection. The correlation between the P/C ratio in the spot urine samples and urinary protein excretion in the 24-hour collections was examined using the Spearman correlation test.

RESULTS

It was found a good positive correlation between the P/C ratio and 24-hour protein excretion, with a correlation coefficient (r) of 0.758. The best cut-off which gave the maximum area under the curve was 0.45 for 300 mg, 0.9 for 1000 mg, 1.16 for 2000 mg, 1.49 for 3000 mg, 2.28 for 4000 mg and 2.63 for 5000 mg per 24h. A P/C ratio above 0.9 strongly predicts significant proteinuria for more than 1 gram (AUC 0.97, 95% CI: 0.94-0.99 and sensitivity, specificity, positive and negative predictive value of 91%, 95.4%, 95.2%, and 91.2%, respectively).

CONCLUSION

The P/C ratio can be used as a screening test as a good predictor for remarkable proteinuria. The P/C ratio seems to be highly predictive for diagnosis to detect proteinuria over one gram and it could be used as a rapid alternative test in preeclamptic patients not to delay implementation treatment.

Dynamic changes of urinary proteins in a focal segmental glomerulosclerosis rat model

Background

In contrast to blood, which has mechanisms to maintain a homeostatic internal environment, urine is more likely to reflect changes in the body. As urine accumulates all types of changes, identifying the precise cause of changes in the urine proteome is challenging and crucial in biomarker discovery. To reduce the effects of both genetic and environmental factors on the urinary proteome, this study used a rat model of adriamycin-induced nephropathy resembling human focal segmental glomerulosclerosis (FSGS) development.

Results

Urine samples were collected at before adriamycin administration and day3, 7, 11, 15 and 23 after. Urinary proteins were profiled by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Of 23 changed proteins with disease development, 20 have human orthologs, and 13 proteins were identified as stable in normal human urine, meaning that changes in these proteins are more likely to reflect disease. Fifteen of the identified proteins have not been established to function in FSGS development. Seven proteins were selected for verification in ten more rats as markers closely associated with disease severity by western blot.

Conclusion

We identified proteins changed in different stages of FSGS in rat models, which may aid in biomarker development and the understanding of FSGS pathogenesis.

Optimal proteinuria target for renoprotection in patients with IgA nephropathy

Background

Proteinuria is a target for renoprotection in kidney diseases. However, optimal level of proteinuria reduction in IgA nephropathy (IgAN) is unknown.

Methods

We conducted a retrospective observational study in 500 patients with biopsy-proven IgAN. Time-averaged proteinuria (TA-P) was calculated as the mean of every 6 month period of measurements of spot urine protein-to-creatinine ratio. The study endpoints were a 50% decline in estimated glomerular filtration rate (eGFR), onset of end-stage renal disease (ESRD), and slope of eGFR.

Results

During a median follow-up duration of 65 (12–154) months, a 50% decline in eGFR occurred in 1 (0.8%) patient with TA-P of <0.3 g/g compared to 6 (2.7%) patients with TA-P of 0.3–0.99 g/g (hazard ratio, 2.82; P = 0.35). Risk of reaching a 50% decline in eGFR markedly increased in patients with TA-P of 1.0–2.99 g/g (P = 0.002) and those with TA-P≥3.0 g/g (P<0.001). ESRD did not occur in patients with TA-P<1.0 g/g compared to 26 (20.0%) and 8 (57.1%) patients with TA-P of 1.0–2.99 and ≥3.0 g/g, respectively. Kidney function of these two groups deteriorated faster than those with TA-P<1.0 g/g (P<0.001). However, patients with TA-P of 0.3–0.99 g/g had a greater decline of eGFR than patients with TA-P<0.3 g/g (−0.41±1.68 vs. −0.73±2.82 ml/min/1.73 m²/year, P = 0.03).

Conclusion

In this study, patients with TA-P<1.0 g/g show favorable outcomes. However, given the faster eGFR decline in patients with TA-P of 0.3–0.99 g/g than in patients with TA-P<0.3 g/g, the ultimate optimal goal of proteinuria reduction can be lowered in the management of IgAN.

The clinical association of the blood pressure variability with the target organ damage in hypertensive patients with chronic kidney disease

It is known that blood pressure variability (BPV) can independently affect target organ damage (TOD), even with normal blood pressure. There have been few studieson chronic kidney disease (CKD) patients. We evaluated the relationship between BPV and TOD in a cross-sectional, multicenter study on hypertensive CKD patients. We evaluated 1,173 patients using 24-hr ambulatory blood pressure monitoring. BPV was defined as the average real variability, with a mean value of the absolute differences between consecutive readings of systolic blood pressure. TOD was defined as left ventricular hypertrophy (LVH) (by the Romhilt-Estes score ≥4 in electrocardiography) and kidney injury (as determined from an estimated glomerular filtration rate [eGFR]<30 mL/min/1.73 m(2) and proteinuria).The mean BPV of the subjects was 15.9±4.63 mmHg. BPV displayed a positive relationship with LVH in a univariate analysis and after adjustment for multi-variables (odds ratio per 1 mmHg increase in BPV: 1.053, P=0.006). In contrast, BPV had no relationship with kidney injury. These data suggest that BPV may be positively associated with LVH in hypertensive CKD patients.

Variation of urinary protein to creatinine ratio during the day in women with suspected pre-eclampsia

OBJECTIVE

To investigate the stability throughout the day of the protein to creatinine ratio (PCR) in spot urine, to demonstrate whether the PCR is a valid alternative for 24-hour protein investigation in pregnant women.

DESIGN

Prospective study.

SETTING

Tertiary referral university centre.

POPULATION

Women suspected of having pre-eclampsia, admitted to the Erasmus Medical Centre.

METHODS

Twenty-four-hour urine collections and simultaneously three single voided 5-ml aliquots were obtained at 8 a.m., 12 a.m. (noon) and 5 p.m. A PCR was measured in each specimen and compared with the 24-hour protein excretion.

MAIN OUTCOME MEASURES

The 24-hour proteinuria and PCR measured in spontaneous voids.

RESULTS

The PCRs correlated strongly with each other and with the 24-hour protein excretion but did show variation throughout the day (mean coefficient of variation 36%; 95% confidence interval 31-40%). The coefficient of variation was unrelated to the degree of 24-hour proteinuria. Receiver operating characteristics curves to discriminate between values below and greater than or equal to the threshold of 0.3 g protein per 24-hour had an area under the curve of respectively 0.94 (8 a.m.), 0.96 (noon) and 0.97 (5 p.m.). Sensitivities at 8 a.m., noon and 5 p.m. were respectively 89%, 96% and 94%; specificities were 75%, 78% and 78% with the proposed PCR cut-off of 30 mg/mmol (0.26 g/g) (National Institute for Health and Care Excellence guidelines).There is no evidence of a difference between the three measurement times regarding the sensitivities and specificities.

CONCLUSION

The PCR determined in spot urine varies throughout the day but is a valid alternative for 24-hour urine collections in pregnant women. It is especially useful to rapidly identify clinically relevant proteinuria.

Estimated albumin excretion rate versus urine albumin-creatinine ratio for the assessment of albuminuria: a diagnostic test study from the Prevention of Renal and Vascular Endstage Disease (PREVEND) Study

BACKGROUND

Albumin-creatinine ratio (ACR) in spot urine samples is recommended for albuminuria screening instead of measured albumin excretion rate (mAER) in 24-hour urine collections. In patients with extremes of muscle mass, differences in spot urine creatinine values may lead to under- or overestimation of mAER by ACR. We hypothesized that calculating estimated AER (eAER) using spot ACR and estimated creatinine excretion rate (eCER) may improve albuminuria assessment.

STUDY DESIGN

Diagnostic test study.

SETTING & PARTICIPANTS

2,711 community-living individuals from the general population of the Netherlands participating in the PREVEND (Prevention of Renal and Vascular Endstage Disease) Study.

INDEX TEST

eAER was computed as the product of ACR and eCER. eCER was computed using 3 previously validated methods (Ix, Ellam, and Walser).

REFERENCE TEST

mAER, based on two 24-hour urine collections. Accuracy of the eAER and ACR were defined as the percentage of participants falling within 30% (P30) of mAER.

RESULTS

Mean age was 49 years, 46% were men, mean estimated glomerular filtration rate was 84 ± 15 mL/min/1.73 m(2), and median mAER was 7.2 (IQR, 5.4-11.0) mg/d. Mean measured CER was 1,381 mg/d, and median ACR was 4.9 mg/g. Using the Ix equation, median eAER was 6.4 mg/d. In the full cohort, eAER was more accurate and less biased compared to ACR (P30, 48.9% vs 33.6%; bias, -34.2% vs -14.1%, respectively). In subgroup analysis, improvement was most notable in the middle and highest weight tertiles and in men. Using the other methods for eCER produced similar results.

LIMITATIONS

Little ethnic heterogeneity and a generally healthy cohort make extension of findings to other races and the chronically ill uncertain.

CONCLUSIONS

In a large community-dwelling cohort, eAER was more accurate than ACR in assessing albuminuria.

High urine IP-10 levels associate with chronic HCV infection

OBJECTIVES

Independent of IL-28B polymorphisms, blood IP-10 is a promising biomarker for predicting therapy response in chronic HCV infection. Urine IP-10 has been proposed as a biomarker in tuberculosis, but to date, no urine biomarkers for HCV infection have been evaluated. In this cross-sectional study, we assessed whether IP-10 is detectable in the urine of chronically HCV-infected patients, and if so, whether urine IP-10 correlates with serum IP-10 and HCV-specific clinical parameters.

METHODS

IP-10 was measured by ELISA in serum and urine concomitantly taken from 38 HCV-viremic patients, 10 cured-HCV subjects and 11 healthy donors enrolled as controls.

RESULTS

The urine of HCV-viremic patients showed measurable amounts of IP-10, although significantly lower than in serum (p < 0.0001). Urine IP-10 was normalized with creatinuria levels and we found that the urine IP-10/creatinuria ratio was significantly higher in HCV-viremic patients than in cured-HCV subjects (p = 0.002) and healthy donors (p = 0.008), and that it significantly correlated with transaminases (p = 0.01), although the correlation was low. Similarly, the serum IP-10 level significantly associated with HCV-viremic patients (p < 0.0001) and correlated with transaminases (p < 0.0001).

CONCLUSIONS

For the first time to our knowledge, we show that IP-10 is detected and increased in the urine of HCV-viremic patients compared to healthy donors and cured-HCV subjects.

Evaluating an alternative method for rapid urinary creatinine determination

Creatinine (CR) is an endogenously produced chemical that is routinely assayed in urine specimens to assess kidney function and sample dilution. The industry-standard method for CR determination, known as the kinetic Jaffé (KJ) method, relies on an exponential rate of a colorimetric change, and can therefore require automated processing equipment for moderate- to high-throughput analysis (hundreds to thousands of samples per day). This study evaluates an alternative colorimetric method, the "plateau Jaffé" (PJ) method, which utilizes the chemistry of the KJ method, a commercially available kit, and a multipoint calibration curve. This method is amenable to moderate-throughput sample analysis and does not require automated processing equipment. Thirty-two spot urine samples from healthy adult volunteers were analyzed for creatinine concentration (CRc) using the KJ and PJ methods. Samples were also analyzed using a liquid chromatography time-of-flight mass spectrometry (LC-TOF/MS) method, which acted as an analytical control. Replicate measurements of spot samples (natural log-transformed values) were used to estimate method precision, and linear regression models were used to evaluate method accuracy (LC-TOF/MS measurements were considered the analytical benchmark). Measurement precision was comparable across all three methods, with coefficent of variation estimates ranging from 3 to 6%. Regression models generally showed good agreement across methods with R(2) estimates ranging from .996 to .998, slope estimates ranging from .944 to .986, and y-intercept estimates ranging from 0.111 to 0.303. Minor bias (between 2 and 16%) was observed across methods at the tails of the measurement distributions. The provided regression equations can be used to adjust for this bias and to improve CR measurement comparisons across studies employing different methods. Considering these results, the PJ method is a suitable alternative to the industry standard KJ method for urinary CRc determination. It can be implemented for moderate-throughput sample analysis using modest and commonly available lab instrumentation and manual sample preparation techniques.