Correlation of urine protein/creatinine ratios to 24-h urinary protein for quantitating proteinuria in children

Silencing HE4 alleviates the renal fibrosis in lupus nephritis mice by regulating the C3/MMPs/prss axis

To explore the regulatory effect of human epididymis protein 4 (HE4) on renal fibrosis in mice with lupus nephritis (LN) and the underlying mechanism. Ten-week old MRL/LPR mice were injected with HE4 shRNA adenovirus vector through the renal pelvis for 5 days. Renal tissues were extracted for HE and Masson staining to evaluate pathological changes and fibrosis in lupus nephritis mice. The level of urine protein was measured using a biochemical analyzer, while the expression level of HE4 and p-NF-κB p65 in renal tissues was visualized using an immunofluorescence assay. The level of β2-microglobulin (β2-MG), neutrophil gelatinase-associated lipocalin (NGAL), and kidney injury molecule 1 (Kim-1) was determined by the immunohistochemical assay. Western blotting was used to determine the levels of C3, HE4, matrix metalloproteinase-2 (MMP2), MMP9, p-p65, prss23, and prss35 in renal tissues. Compared to wild-type C57BL/6 mice, MRL/LPR mice showed a marked increase in the number of glomeruli, hyperplasic basement membrane, severe infiltration of inflammatory cells in renal tubules and glomeruli, obvious necrosis in glomeruli, elevated fibrosis levels, and increased levels of urine protein, β2-MG, NGAL, Kim-1, C3, HE4, MMP2, MMP9, and p-p65; and decreased levels of prss23 and prss35 were observed in MRL/LPR mice. After the administration of the HE4 shRNA adenovirus vector, the repaired structure of renal tubules and glomeruli improved infiltration of inflammatory cells, reduced collagen fiber and urine protein, suppressed levels of C3, HE4, MMP2, MMP9, and p-P65, and facilitated the expression of prss23 and prss35 which were observed. Silencing HE4 improved renal fibrosis and inhibited inflammation in mice with lupus nephritis, which may play a role in inhibiting C3/MMPs and promoting prss-related protein expression.

Renal Function Impairment in Children With Congenital Cytomegalovirus Infection: A Cross-sectional Study

BACKGROUND

We aimed to determine the prevalence and severity of glomerular and tubular renal dysfunction by means of urinalysis in infants and toddlers with congenital cytomegalovirus infection (cCMV) and their association with cCMV disease, viruria and antiviral treatment.

METHODS

This cross-sectional study was done using the Spanish Registry of Congenital Cytomegalovirus Infection. First-morning urine samples were collected from January 2016 to December 2018 from patients <5 years old enrolled in Spanish Registry of Congenital Cytomegalovirus Infection. Samples were excluded in case of fever or other signs or symptoms consistent with acute infection, bacteriuria or bacterial growth in urine culture. Urinary protein/creatinine and albumin/creatinine ratios, urinary beta-2-microglobulin levels, hematuria and CMV viruria were determined. A 0.4 cutoff in the urinary albumin/protein ratio was used to define tubular (<0.4) or glomerular (>0.4) proteinuria. Signs and symptoms of cCMV at birth, the use of antivirals and cCMV-associated sequelae at last available follow-up were obtained from Spanish Registry of Congenital Cytomegalovirus Infection.

RESULTS

Seventy-seven patients (37 females, 48.1%; median [interquartile range] age: 14.0 [4.4-36.2] months) were included. Symptom-free elevated urinary protein/creatinine and albumin/creatinine ratios were observed in 37.5% and 41.9% of patients, respectively, with tubular proteinuria prevailing (88.3%) over glomerular proteinuria (11.6%). Proteinuria in the nephrotic range was not observed in any patients. In multivariate analysis, female gender was the only risk factor for tubular proteinuria (adjusted odds ratio = 3.339, 95% confidence interval: 1.086-10.268; P = 0.035). cCMV disease at birth, long-term sequelae, viruria or the use of antivirals were not associated with urinalysis findings.

CONCLUSIONS

Mild nonsymptomatic tubular proteinuria affects approximately 40% of infants and toddlers with mostly symptomatic cCMV in the first 5 years of life.

Comparison of three spot proteinuria measurements for pediatric nephrotic syndrome: based on the International pediatric Nephrology Association 2022 Guidelines

BACKGROUND

Pediatric nephrotic syndrome (NS) requires routine proteinuria monitoring, which is costly and affects patients' quality of life. The gold-standard 24-h urine protein (UP) measurement is challenging in children, and first-morning urine collection requires specific conditions, making it difficult in outpatient settings. Studies have reported comparability of second or random morning urine sample to the first-morning specimen. This study aimed to compare outcomes of random morning proteinuria measurements to 24-h UP and the roles of the urinary protein creatinine ratio (UPCR) and dipstick tests in pediatric NS, based on International Pediatric Nephrology Association (IPNA) 2022 Guidelines.

METHOD

Twenty-four-hour and morning urine samples were collected from 92 pediatric NS patients. These were subjected to automated analyses for 24-h UP, UPCR, and semi-automated dipstick analysis. A blinded doctor performed manual dipstick analysis.

RESULTS

UPCR had a stronger correlation with 24-h UP than with automated and manual urine dipstick tests. UPCR had the highest sensitivity and specificity for predicting no remission/relapse and high sensitivity but low specificity for complete remission. The optimal UPCR cutoff for remission was 0.44 mg/mg and for no remission/relapse was 2.08 mg/mg. Automated and manual dipstick tests demonstrated limited sensitivity but high specificity and similar AUC values for remission/relapse.

CONCLUSION

UPCR was sensitive and specific for diagnosing no remission/relapse and sensitive but not specific for detecting remission. Manual and automated urine dipstick tests were comparable for remission and no remission/relapse detection. This study supports the IPNA 2022 Guidelines, as 2 mg/mg was the optimal UPCR cutoff for no remission/relapse, while for remission the optimal cutoff was 0.4 mg/mg.

Etiology and outcomes of acute kidney disease in children: a cohort study

BACKGROUND

There is paucity of information regarding the etiology and outcomes of Acute Kidney Disease (AKD) in children.

METHODS

The objectives of this cohort study were to evaluate the etiology and outcomes of AKD; and analyze predictors of kidney survival (defined as free of CKD 2, 3a, 3b, 4 or 5). Patients aged 1 month to 18 years who developed AKD over a 4-year-period (January 2018-December 2021) were enrolled. Survivors were followed-up at the pediatric nephrology clinic, and screened for residual kidney injury.

RESULTS

Among 5710 children who developed AKI, 200 who developed AKD were enrolled. The median (IQR) eGFR was 17.03 (10.98, 28) mL/min/1.73 m². Acute glomerulonephritis, acute tubular necrosis (ATN), hemolytic uremic syndrome (HUS), sepsis-associated AKD, and snake envenomation comprised of 69 (34.5%), 39 (19.5%), 24 (12%), 23 (11.5%) and 15 (7.5%) of the patients respectively. Overall, 88 (44%) children required kidney replacement therapy (KRT). There were 37 (18.5%) deaths within the AKD period. At a follow-up of 90 days, 32 (16%) progressed to chronic kidney disease stage-G2 or greater. At a median (IQR) follow-up of 24 (6, 36.5) months (n = 154), 27 (17.5%) had subnormal eGFR, and 20 (12.9%) had persistent proteinuria and/or hypertension. Requirement of KRT predicted kidney survival (free of CKD 2, 3a, 3b, 4 or 5) in AKD (HR 6.7, 95% CI 1.2, 46.4) (p 0.04).

CONCLUSIONS

Acute glomerulonephritis, ATN, HUS, sepsis-associated AKD and snake envenomation were common causes of AKD. Mortality in AKD was 18.5%, and 16% progressed to CKD-G2 or greater at 90-day follow-up.

Evaluation of Proteinuria and Hematuria in Ambulatory Setting

Proteinuria and/or hematuria are common findings in ambulatory settings. Proteinuria can be glomerular and/or tubular in origin and it may be transient, orthostatic, or persistent. Persistent proteinuria may be indicative of a serious kidney pathology. Hematuria, which denotes the presence of an increased number of red blood cells in the urine, can be gross or microscopic. Hematuria can originate from the glomeruli or other sites of the urinary tract. Asymptomatic microscopic hematuria or mild proteinuria in an otherwise healthy child is less likely to be of clinical significance. However, the presence of both requires further workup and careful monitoring.

How to define and assess the clinically significant causes of hematuria in childhood

Given the wide diversity of causes of hematuria, ranging from simple urinary tract infections with rapid recovery to severe glomerulonephritis with fast decline in kidney function, it is essential to recognize the underlying disease. The first objective of the assessment is to determine whether the cause of the hematuria is medically significant. The combination of hematuria with proteinuria, the presence of hypertension, or worsening kidney function can represent signs of progressive kidney disease. Differentiating the various causes of hematuria is often simple and obvious based on the clinical signs and gross appearance of the urine. However, in some instances, additional non-invasive investigations, such as ultrasound imaging, urinary red cell morphology, measurement of calcium and other solutes in the urine, evaluation of kidney function, and protein excretion, are needed to elucidate the nature of the hematuria. Taking a detailed family history can help in establishing the underlying cause in cases of familial hematuria. On the other hand, the decision to perform a kidney biopsy in children with asymptomatic hematuria remains a challenging issue for clinicians. Ultimately, the frequency of diagnosis of glomerular involvement causing hematuria may depend on the threshold for performing a kidney biopsy. The following review will focus on the diagnostics of hematuria, starting with difficulties regarding its definition, followed by various means to differentiate between urinary, glomerular, and other causes, and finally reviewing the most common diseases that, due to their frequency or their effect on kidney function, present a diagnostic challenge in everyday practice.

Etiology, Comorbidities, and Rate of Progression of Pediatric Chronic Kidney Disease: A Cohort Study

OBJECTIVES

To evaluate the etiology of pediatric chronic kidney disease (CKD), assess comorbidities, and identify rate of progression of CKD and its risk factors.

METHODS

Children aged 2-18 y with the Kidney Disease Improving Global Outcome (KDIGO) CKD stages 2-4 were enrolled. The etiology of CKD and its comorbidities were recorded. Kaplan-Meier survival curves were used to analyze the time to progression of CKD.

RESULTS

Of the 131 patients enrolled, CKD stages 2, 3a, 3b, and 4 constituted 62 (47.3%), 17 (13%), 26 (19.8%), and 26 (19.8%), respectively. At the last follow-up [at median (IQR) 24 (12, 30) mo], the number of children in CKD stages 2, 3a, 3b, 4 and 5 were 48 (36.6%), 16 (12.2%), 23 (17.6%), 28 (21.4%), and 16 (12.2%), respectively. Etiologies of CKD included obstructive uropathy [48 (36.6%)], chronic glomerular disease [19 (14.5%)], reflux nephropathy [14 (10.7%)] and cystic renal disease [11 (8.3%)]. Comorbidities during follow-up included CKD-MBD [87 (66.4%)], metabolic acidosis [95 (72.5%)], hypertension [88 (67.1%)], growth retardation [69 (52.6%)], and anemia [63 (48.1%)]. The number of patients with metabolic acidosis, hypertension, MBD and anemia in CKD stage 2 were 27 (56%), 26 (54.2%), 24 (50%), 15 (30%), respectively. The median (IQR) rate of decline in eGFR was 3.3 (2, 4.6) mL/min/1.73 m²/y. On multivariable analysis, proteinuria [hazard ratio 3.5 (95% CI 1.4, 8.8) p = 0.01] and hyperphosphatemia [hazard ratio 2.2 (95% CI 1.1, 4.3) p = 0.03] were significant predictors for progression of CKD.

CONCLUSIONS

Even the earlier stages of CKD had significant comorbidities. The median decline in eGFR was 3.3 mL/min/1.73 m²/y. Proteinuria and hyperphosphatemia were the risk factors for progression of CKD.

Diagnostic accuracy of the American College of Rheumatology-1997, the Systemic Lupus International Collaborating Clinics-2012, and the European League Against Rheumatism-2019 criteria for juvenile systemic lupus erythematosus: A systematic review and network meta-analysis

IMPORTANCE/BACKGROUND

Several diagnostic criteria have been developed to effectively diagnose systemic lupus erythematosus (SLE). Three criteria are most common, namely the American College of Rheumatology (ACR)-1997, the Systemic Lupus International Collaborating Clinics (SLICC)-2012, and the European League Against Rheumatism (EULAR/ACR)-2019. Whether they also apply to juvenile SLE is unclear.

OBJECTIVE

To examine the diagnostic accuracy of ACR-1997, SLICC-2012, and EULAR/ACR-2019 for juvenile SLE.

DATA SOURCES

A comprehensive search of PubMed, Cochrane, and Embase was conducted up to 26 March 2022.

STUDY SELECTION

We included all study designs in which patients had any index tests for ACR-1997, SLICC-2012, or EULAR/ACR-2019; both full-text papers and conference abstracts published in English were used. Exclusion criteria were as follows: (1) case reports; (2) adult subjects; or (3) did not report sufficient information to acquire true positive, false positive, true negative, and false negative values of diagnostic criteria.

DATA EXTRACTION AND SYNTHESIS

Two authors independently screened studies, extracted relevant data, and assessed the risk of bias.

MAIN OUTCOMES AND MEASURES

First, a meta-analysis of the diagnostic accuracy of EULAR/ACR-2019 and a hierarchical summary receiver operating characteristic (HSROC) model was performed to estimate sensitivity and specificity with 95% confidence intervals (CIs). We then carried out a network meta-analysis to compare the performances of these three diagnostic criteria.

RESULTS

In total, 17 relevant studies that included 2339 juvenile SLE patients were eligible to analyze pooled accuracy. In the meta-analysis, 10 studies (1613 cases) reported the diagnostic performance of EULAR/ACR-2019, showing a pooled sensitivity of 0.92 (95% CI, 0.89-0.95), pooled specificity of 0.89 (0.77-0.95), and area under HSROC of 0.96 (0.94-0.97). In the network meta-analysis, the SLICC-2012 (0.94, 0.92-0.96) had the highest sensitivity, followed by EULAR/ACR-2019 (0.93, 0.90-0.95), and ACR-1997 (0.78, 0.72-0.82); the ACR-1997 (0.96, 0.92-0.98) demonstrated the highest specificity. EULAR/ACR-2019 (0.92, 0.87-0.96) and SLICC-2012 (0.92, 0.86-0.96) had the similar specificity.

CONCLUSIONS AND RELEVANCE

We found that the applicability of the new EULAR/ACR-2019 criteria in juvenile SLE is not yet the best diagnostic tool.

TRIAL REGISTRATION

PROSPERO CRD42022321514.

Clinical Efficacy of Persian Medicine Diet Combined with Western Medicine-Based Diet on Proteinuria in Pediatric Nephrotic Syndrome: A Randomized Controlled Clinical Trial

Introduction

Nephrotic syndrome (NS) is a common chronic kidney disorder during childhood. The most important characteristic of this disease is proteinuria. The Persian medicine (PM) has important dietary recommendations for strengthening the kidney function and treatment of this disease. The aim of this study was to investigate the effect of a diet including PM recommendations and general principles of Western medicine.

Materials and Methods

Twenty children with nephrotic syndrome were randomly divided into intervention and control groups and monitored for one month. The control group received a diet based on the general principles of Western medicine. In the intervention group, in addition to the Western medicine diet, dietary recommendations of PM were also prescribed including the pomegranate (Cydonia oblonga mill.), quince (Cydonia oblonga mill.), and whole grains (wheat and barley). A 24-hour dietary questionnaire was applied and anthropometric and biochemical indices including spot urine protein (proteinuria), albumin (Alb), urea, creatinine (Cr), total cholesterol (TC), and triglyceride (TG) were measured before and after the study.

Results

The amount of protein intake reduced significantly in the diet of both groups but the differences between the two groups were not significant. Proteinuria reduced significantly in both the Western and PM groups; however, proteinuria was significantly lower in the Persian medicine group compared to the control group. TC and Cr levels reduced significantly in the intervention group, although the changes were not significant compared to the control group.

Conclusion

The results of this study showed that adding dietary recommendations of the Persian medicine to the general rules of the Western medicine diet reduced proteinuria and improved the combat against nephrotic syndrome.

Diagnostic efficacy and influence factors of urinary protein/creatinine ratio replacing 24-h urine protein as an evaluator of proteinuria in children

PURPOSE

The aim was to investigate the diagnostic efficacy of urinary protein/creatinine ratio (UPCR) and factors influencing its substitutability of 24-h urine protein (24hUP) in children with proteinuria.

METHODS

A total of 356 children were recruited, including 149 with non-nephrotic-range proteinuria and 207 with nephrotic-range proteinuria which were further divided into Henoch-Schönlein purpura nephritis (HSPN), lupus nephritis (LN), and primary nephrotic syndrome (PNS). The urine protein and creatinine were measured by routine methods. Bland-Altman analysis was used to test the agreement. Spearman correlation was performed to evaluate the relevance. The receiver operating characteristic curve was used to analyze the diagnostic efficacy of UPCR.

RESULTS

Bland-Altman analysis showed there was an excellent agreement between UPCR and 24hUP in each group. Correlations between UPCR and 24hUP were strong in 356 children (r = 0.869) and in the non-nephrotic-range proteinuria group (r = 0.806), but moderate in nephrotic-range proteinuria group (r = 0.586). With the increase of nephrotic-range proteinuria, the correlations between UPCR and 24hUP were decreased further, however, after UPCR was adjusted by 24-h urine creatinine (24hUCr), the correlation coefficient was improved (r = 0.682). In three subgroups with nephrotic-range proteinuria, high correlation coefficient (r = 0.731) was observed in HSPN, but not in LN (r = 0.552) and PNS (r = 0.563). The sensitivity and specificity of UPCR for diagnosing nephrotic-range proteinuria were 89.9 % and 92.2%.

CONCLUSIONS

UPCR is competent in evaluating proteinuria. The degree of proteinuria, 24hUCr and the underlying pathological types of renal disease may be the important influencing factors in the correlation between UPCR and 24hUP in children with nephrotic-range proteinuria.

Children with Intestinal Failure Maintain Their Renal Function on Long-Term Parenteral Nutrition

BACKGROUND

Long-term parenteral nutrition (PN) has been associated with renal complications, including hypercalciuria, nephrocalcinosis, proteinuria and reduced glomerular filtration rate (GFR). Pediatric data are scarce and mostly short-term. Our study aimed to evaluate renal complications in children with intestinal failure (IF) receiving long-term PN.

METHODS

A cross-sectional study was performed in a tertiary pediatric IF clinic of patients receiving home-PN treatment for more than 1 year. Data regarding medical background, anthropometrics, laboratory investigations and abdominal sonography were retrieved.

RESULTS

Complete data were available for 15 children (67% males), with a median age of 6 (range 1.5-15) years and a median (IQR) PN duration of 4 (1.5-6) years. Low-grade proteinuria was identified in 61% and microalbuminuria in 30% of the cohort. Hypercalciuria and hyperoxaluria were present in 50% and 46%, respectively. One patient had nephrocalcinosis. The estimated GFR was normal in all but one patient who had pre-existing kidney disease.

CONCLUSIONS

Pediatric IF patients can present with preserved kidney function after years of PN treatment. Despite the high prevalence of hypercalciuria, nephrocalcinosis was not common. Base line and long-term monitoring of various aspects of renal function would be essential to characterize the effects of prolonged PN on kidney functions in pediatric patients.

Reference values of urine protein/creatinine ratio in healthy Dalian adults

Background

The urine protein/creatinine ratio (UPCR) is commonly used in current clinical practice. However, there are only few published clinical data on UPCR from large cohorts of Chinese adults. This study aimed to determine the overall and age‐ and sex‐specific UPCR reference values for healthy Dalian adults.

Methods

According to the Clinical & Laboratory Standards Institute EP28‐A3c guidelines, 1321 healthy Dalian adults (646 men and 675 women) aged 20–69 years were enrolled. Urine protein and creatinine levels were analyzed in the random morning spot urine samples, and UPCR was calculated. The 95th percentile of the UPCR was used as the normal upper limit. The Mann–Whitney U test was used to test differences among groups.

Results

The UPCR reference value was 141.7 mg/g for the entire cohort, 128.7 mg/g for men, and 150.8 mg/g for women. In addition, women had relatively higher UPCR values than men in the same age group. We also compared the UPCR reference values between different estimated glomerular filtration rate (eGFR) groups and found that women had significantly higher UPCR values than men in the normal eGFR groups.

Conclusions

This study provides the overall and age‐ and sex‐specific UPCR reference values for healthy Dalian adults.

IgA Nephropathy as the Initial Presentation of Celiac Disease in an Adolescent

Immunoglobulin A (IgA) nephropathy (Berger's disease) is the most common glomerulonephritis worldwide. The disease typically is chronic and lifelong and eventually progresses to impaired renal function in a substantial proportion of cases. It has been known for some time that there is a correlation between IgA nephropathy and celiac disease, but until now it has remained unclear whether treatment of the underlying celiac disease has any meaningful impact on the progression of the renal disease. Therefore, until now, screening for celiac disease in patients presenting with IgA nephropathy has not been universally recommended in the absence of suggestive gastrointestinal symptoms. This report describes a case of IgA nephropathy in an adolescent boy that turned out to be the initial presentation of celiac disease. More importantly, it documents the complete laboratory normalization of his renal anomalies at 5-year follow-up after treatment of his celiac disease with implementation of a gluten-free diet. This case highlights the importance of awareness that suspected IgA nephropathy, even in the absence of gastrointestinal symptoms, should prompt screening for underlying celiac disease as a potential, and possibly treatable, cause.

Review: Detection and quantification of proteins in human urine

Extensive medical research showed that patients, with high protein concentration in urine, have various kinds of kidney diseases, referred to as proteinuria. Urinary protein biomarkers are useful for diagnosis of many health conditions – kidney and cardio vascular diseases, cancers, diabetes, infections. This review focuses on the instrumental quantification (electrophoresis, chromatography, immunoassays, mass spectrometry, fluorescence spectroscopy, the infrared spectroscopy, and Raman spectroscopy) of proteins (the most of all albumin) in human urine matrix. Different techniques provide unique information on what constituents of the urine are. Due to complex nature of urine, a separation step by electrophoresis or chromatography are often used for proteomics study of urine. Mass spectrometry is a powerful tool for the discovery and the analysis of biomarkers in urine, however, costs of the analysis are high, especially for quantitative analysis. Immunoassays, which often come with fluorescence detection, are major qualitative and quantitative tools in clinical analysis. While Infrared and Raman spectroscopies do not give extensive information about urine, they could become important tools for the routine clinical diagnostics of kidney problems, due to rapidness and low-cost. Thus, it is important to review all the applicable techniques and methods related to urine analysis. In this review, a brief overview of each technique's principle is introduced. Where applicable, research papers about protein determination in urine are summarized with the main figures of merits, such as the limit of detection, the detectable range, recovery and accuracy, when available.

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Urinary protein biomarkers are useful for diagnosis of many conditions: kidney and cardio vascular diseases, cancers.

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Liquid chromatography – mass spectroscopy is a powerful tool for urine proteomics, but used mostly in science.

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Immunoassays are widely used in both clinical and bio-analytical laboratories.

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IR and Raman spectroscopies are promising tools for diagnostics of urine due to low-cost and rapidness.