Estimating glomerular filtration rate in children: evaluation of creatinine- and cystatin C-based equations

Comparison of different eGFR formulas to measured glomerular filtration rate using iohexol in children and adolescents with mild chronic kidney disease

Estimated glomerular filtration rate (eGFR) based on different formulas is commonly used as a bedside tool to assess kidney function in children and young adults. The purpose of this study was to perform a measurement of glomerular filtration rate (mGFR) in children with chronic kidney disease (CKD) with a standard 5-point protocol using iohexol clearance and compare it to a simplified protocol for mGFR determination and to some of the most commonly used eGFR formulas. A 5-point standard protocol using iohexol clearance was used for determination of mGFR in 50 children with mild stages of CKD. The result was compared to 2- and 3-point sampling protocol as well as with some standard children eGFR formulas. We calculated the prediction performance for eGFR formulas to distinguish CKD1 and CKD 2 stages, formulas' accuracy, and cutoff values. Data were prospectively collected. All eGFR formulas exhibited a statistically significant positive correlation with mGFR. The best correlation was found with CKID2012 eGFR formula and with cystatin C-based eGFR formulas. The correlation between standard and simplified protocols for mGFR determination was also strong, while creatinine clearance did not prove to be a reliable method for estimating GFR. The error distribution with simplified protocols was not dispersed. The prediction value was strong for CKID2012 and bedside Schwartz formula. Conclusion: Fewer sampling points can be safely used for measuring GFR in children. eGFR formulas that are not based solely on creatinine should be considered more often in GFR estimation. What is Known? • Iohexol clearance is an established method of measuring GFR in children and adolescents using different protocols. • Estimating GFR in children and adolescents is troublesome and is done using different formulas with anthropometric and biochemical markers in children and adolescents. What is New? • Iohexol measurement with two or three blood withdrawals can reliably distinguish between CKD1 and CKD2 patients. • eGFR formulas have moderate reliability to predict distinguish between CKD1 and CKD2 patients, of which CKID2012 and bedside Schwartz formula were the most accurate in our study.

Creatinine-based formulas are not ideal to estimate glomerular filtration rate in selected pediatric patients: data from a tertiary pediatric nephrology center

BACKGROUND

Evaluating glomerular filtration rate (GFR) remains challenging in pediatrics; new formulas were developed to increase performance of GFR estimation (eGFR). We aimed to evaluate the recently published formulas as applied to another pediatric population.

METHODS

A retrospective study was conducted in a cohort of 307 patients with a "kidney risk" (mean age 12.1 ± 4.5 years, sex ratio 1/1) assessed in a tertiary pediatric nephrology center and a mean measured GFR (mGFR) using plasma iohexol clearance of 85.5 ± 25.3 mL/min/1.73 m2; creatinine levels were measured by IDMS-standardized enzymatic method and cystatin C by immunonephelometry. The following eGFRs were calculated: Schwartz2009, Schwartz-Lyon, CKiDU25creat, and EKFC for eGFR using creatinine (eGFR-creat), CKiDU25cys and FAScys for eGFR using cystatin (eGFR-cys) as well as combined SchwartzCreat-Cys, average (CKiDU25creat-CKiDU25cys), and average (EKFC-FAScys) for eGFR using both biomarkers. The performance of the different formulas was evaluated compared to mGFR by absolute bias measurement and accuracy (p10%, p30%). Results are expressed as mean ± SD.

RESULTS

Creatinine-based formulas and especially the new CKiDU25 and EKFC overestimate GFR, even in children with normal kidney function. However, the bias is constant with these two formulas whatever the age group or gender, contrary to the previously published formulas. In contrast, cystatin C-based equations and combined formulas showed good performance in all age groups and all medical conditions with an acceptable bias and p30%.

CONCLUSIONS

In our pediatric population, the performance of all creatinine-based formulas is inadequate with significant GFR overestimation, mainly in subjects with mGFR > 75 mL/min/1.73 m2. Conversely, cystatin C-based or combined formulas have acceptable performance in patients followed in a tertiary pediatric nephrology unit.

AI-based segmentation of renal enhanced CT images for quantitative evaluate of chronic kidney disease

To quantitatively evaluate chronic kidney disease (CKD), a deep convolutional neural network-based segmentation model was applied to renal enhanced computed tomography (CT) images. A retrospective analysis was conducted on a cohort of 100 individuals diagnosed with CKD and 90 individuals with healthy kidneys, who underwent contrast-enhanced CT scans of the kidneys or abdomen. Demographic and clinical data were collected from all participants. The study consisted of two distinct stages: firstly, the development and validation of a three-dimensional (3D) nnU-Net model for segmenting the arterial phase of renal enhanced CT scans; secondly, the utilization of the 3D nnU-Net model for quantitative evaluation of CKD. The 3D nnU-Net model achieved a mean Dice Similarity Coefficient (DSC) of 93.53% for renal parenchyma and 81.48% for renal cortex. Statistically significant differences were observed among different stages of renal function for renal parenchyma volume (VRP), renal cortex volume (VRC), renal medulla volume (VRM), the CT values of renal parenchyma (HuRP), the CT values of renal cortex (HuRC), and the CT values of renal medulla (HuRM) (F = 93.476, 144.918, 9.637, 170.533, 216.616, and 94.283; p < 0.001). Pearson correlation analysis revealed significant positive associations between glomerular filtration rate (eGFR) and VRP, VRC, VRM, HuRP, HuRC, and HuRM (r = 0.749, 0.818, 0.321, 0.819, 0.820, and 0.747, respectively, all p < 0.001). Similarly, a negative correlation was observed between serum creatinine (Scr) levels and VRP, VRC, VRM, HuRP, HuRC, and HuRM (r = - 0.759, - 0.777, - 0.420, - 0.762, - 0.771, and - 0.726, respectively, all p < 0.001). For predicting CKD in males, VRP had an area under the curve (AUC) of 0.726, p < 0.001; VRC, AUC 0.765, p < 0.001; VRM, AUC 0.578, p = 0.018; HuRP, AUC 0.912, p < 0.001; HuRC, AUC 0.952, p < 0.001; and HuRM, AUC 0.772, p < 0.001 in males. In females, VRP had an AUC of 0.813, p < 0.001; VRC, AUC 0.851, p < 0.001; VRM, AUC 0.623, p = 0.060; HuRP, AUC 0.904, p < 0.001; HuRC, AUC 0.934, p < 0.001; and HuRM, AUC 0.840, p < 0.001. The optimal cutoff values for predicting CKD in HuRP are 99.9 Hu for males and 98.4 Hu for females, while in HuRC are 120.1 Hu for males and 111.8 Hu for females. The kidney was effectively segmented by our AI-based 3D nnU-Net model for enhanced renal CT images. In terms of mild kidney injury, the CT values exhibited higher sensitivity compared to kidney volume. The correlation analysis revealed a stronger association between VRC, HuRP, and HuRC with renal function, while the association between VRP and HuRM was weaker, and the association between VRM was the weakest. Particularly, HuRP and HuRC demonstrated significant potential in predicting renal function. For diagnosing CKD, it is recommended to set the threshold values as follows: HuRP < 99.9 Hu and HuRC < 120.1 Hu in males, and HuRP < 98.4 Hu and HuRC < 111.8 Hu in females.

Metal concentrations and KIM-1 levels in school-aged children: a cross-sectional study

Environmental exposure to heavy metals and metalloids, originating from sources such as mining and manufacturing activities, has been linked to adverse renal effects. This cross-sectional study assessed children's exposure to these elements and its association with urinary kidney injury molecule-1 (KIM-1). We analyzed data from 99 school-aged children residing in nine localities within the state of Colima, Mexico, during the latter half of 2023. Levels of 23 metals/metalloids and urinary KIM-1 were measured using inductively coupled plasma mass spectrometry (ICP-MS) and enzyme-linked immunosorbent assay, respectively. Detectable levels of these contaminants were found in over 91% of participants, with varied exposure profiles observed across locations ( p = 0.019). After adjusting for confounding factors like gender, age, and locality, higher levels of six metals/metalloids (boron, cadmium, cesium, lithium, selenium, zinc) were significantly associated with increased KIM-1 levels. Tailored mitigation efforts are crucial to protect children from regional pollutant burdens. However, limitations exist, as our study did not capture all potential factors influencing heavy metal/metalloid and KIM-1 levels.

Renal function, sex and age influence purines and pyrimidines in urine and could lead to diagnostic misinterpretation

Glomerular filtration rate (GFR) is commonly used in clinical practice for the diagnosis and follow-up of chronic kidney disease. Screening for inborn errors of metabolism (IEM) is based on analysis of biomarkers in urine, reported by their ratio to urinary creatinine (crn). Impaired renal function may complicate the interpretation of several biomarkers used for screening of IEM. Our goal was to investigate the influence of kidney function, in terms of measured GFR (mGFR) on purines and pyrimidines in urine, in addition to the relationship to sex, age, pH and ketosis. Children (n = 96) with chronic kidney disease (CKD), in different CKD stages, were included. Urine samples were obtained prior to the injection of iohexol. Serum samples at 7 time-points were used to calculate mGFR based on iohexol plasma clearance. The association with sex, age, ketosis and pH was examined in samples of the laboratory production from 2015 to 2021 (n = 8192). Age was a highly significant covariate for all markers. GFR correlated positively to several purines and pyrimidines; the ratios hypoxanthine/crn, xanthine/crn and urate/crn (p = 2.0 × 10-14, < 3 × 10-15 and 7.2 × 10-4, respectively), and the ratios orotic acid/crn, uracil/crn, and carbamyl-β-alanine/crn (p = 0.03, 1.4 × 10-6 and 0.003, respectively). The values of urate/crn, xanthine/crn, uracil/crn, and carbamyl-β-alanine/crn were higher in females above 16 years of age. Ketosis and pH influenced some markers. In conclusion, decreased renal function interferes with the excretion of urinary purines and pyrimidines, and this could change decision limits substantially, e.g. result in false negative results in Lesch-Nyhan syndrome. SYNOPSIS: GFR influences purines and pyrimidines in urine. Clinical Trial Registration: ClinicalTrials.gov, Identifier NCT01092260, https://clinicaltrials.gov/ct2/show/NCT01092260?term=tondel&rank=2.

Immunoglobulin A vasculitis nephritis: Current understanding of pathogenesis and treatment

The clinical spectrum of immunoglobulin A vasculitis nephritis (IgAVN) ranges from the relatively common transitory microscopic hematuria and/or low-grade proteinuria to nephritic or nephrotic syndrome, rapidly progressive glomerulonephritis, or even renal failure. Clinical and experimental studies have shown a multifactor pathogenesis: Infection triggers, impaired glycosylation of IgA1, complement activation, Toll-like-receptor activation and B cell proliferation. This knowledge can identify IgAVN patients at a greater risk for adverse outcome and increase the evidence for treatment recommendations.

Identification of biomarkers that predict renal flare in childhood-onset lupus nephritis with mycophenolate acid

BACKGROUND

Children-onset lupus nephritis (cLN) occurs > 50 % of patients with systemic lupus erythematosus. Mycophenolic acid (MPA) is the first-line agent for the induction and maintenance treatment of LN. This study was to explore the predictors of renal flare in cLN.

METHODS

Data from 90 patients were included in population pharmacokinetic (PK) models to predict MPA exposure. Cox regression models and restricted cubic spline were performed in 61 patients to identify the risk factors for renal flare, baseline clinical characteristics and MPA exposures as potential covariates.

RESULTS

PK best fitted a two-compartment model of first-order absorption and linear elimination, with delayed absorption. Clearance increased with weight and immunoglobulin G (IgG), but decreased with albumin and serum creatinine. During follow-up of 1040 (658-1359) days, 18 patients experienced a renal flare, after a median time of 932.5 (663.5-1316) days. Each 1-mg·h/L increase of MPA-AUC was associated with a 6 % decreased risk of an event (HR = 0.94; 95 % CI: 0.90-0.98), while IgG significantly increased this risk (HR = 1.17; 95 % CI: 1.08-1.26). ROC analysis showed that MPA-AUC_0-12h < 35 mg·h/L and IgG > 17.6 g/L had a good prediction of renal flare. Of restricted cubic spline, the risk of renal flares decreased with higher MPA exposure but reached a plateau when AUC_0-12h > 55 mg·h/L, while substantially increases when IgG is > 18.2 g/L.

CONCLUSIONS

Monitoring MPA exposure together with IgG could be very useful during clinical practice to identify patients with a potential high risk of renal flare. This early risk assessment would allow for the treat-to-target and tailored medicine.

Glomerular Filtration Rate Assessment in Children

Glomerular filtration rate (GFR) measurement is a key tool for determining the degree of chronic kidney disease. The assessment of GFR is even more challenging in children than in adults with more variables in the equation than race and sex. Monitoring the progress of the kidney disease can therefore be difficult as in the initial stages of a decline in kidney function, there are no clinical signs. Due to children's growth and development, changes in muscle mass and growth impair GFR estimation based solely on serum creatinine values. More invasive methods of GFR measurement are more reliable, but techniques using ionising agents, requiring large volume blood samples or timed voiding, have limited application in children. This paper reviews the methods of measuring and determining glomerular filtration rate and kidney function in children.

Time to Rethink the Current Paradigm for Assessing Kidney Function in Drug Development and Beyond

Chronic kidney disease (CKD) is an important health issue that affects ~ 9.1% of the world adult population. Serum creatinine is the most commonly used biomarker for assessing kidney function and is utilized in different equations for estimating creatinine clearance or glomerular filtration rate (GFR). The Cockcroft-Gault formula for adults and "original" Schwartz formula for children have been the most commonly used equations for estimating kidney function during the last 3-4 decades. Introduction of standardized serum creatinine bioanalytical methodology has reduced interlaboratory variability but is not intended to be used with Cockcroft-Gault or original Schwartz equations. More accurate equations (for instance, Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) for adults and bedside Schwartz or Chronic Kidney Disease in Children Schwartz equation for children) based on standardized serum creatinine values (and another biomarker-cystatin C) have been introduced and validated in recent years. Recently, the CKD-EPI equation refitted without a race variable was introduced. Clinical practice guidance in nephrology advocates a shift to these equations for managing health care of patients with CKD. The guidance also recommends use of albuminuria in addition to GFR for CKD diagnosis and management. Significant research with large data sets would be necessary to evaluate whether this paradigm would also be valuable in drug dose adjustments. This article attempts to highlight some important advancements in the field from a clinical pharmacology perspective and is a call to action to industry, regulators, and academia to rethink the current paradigm for assessing kidney function to enable dose recommendation in patients with CKD.

Current State of Pediatric Reference Intervals and the Importance of Correctly Describing the Biochemistry of Child Development: A Review

Importance

Appropriately established pediatric reference intervals are critical to the clinical decision-making process and should reflect the physiologic changes that occur during healthy child development. Reference intervals used in pediatric care today remain highly inconsistent across a broad range of common clinical biomarkers.

Observations

This narrative review assesses biomarker-specific pediatric reference intervals and their clinical utility with respect to the underlying biological changes occurring during development. Pediatric reference intervals from PubMed-indexed articles published from January 2015 to April 2021, commercial laboratory websites, study cohorts, and pediatric reference interval books were all examined. Although large numbers of pediatric reference intervals are published for some biomarkers, very few are used by clinical and commercial laboratories. The patterns, extent, and timing of biomarker changes are highly variable, particularly during developmental stages with rapid physiologic changes. However, many pediatric reference intervals do not capture these changes and thus do not accurately reflect the underlying biochemistry of development, resulting in significant inconsistencies between reference intervals.

Conclusions and Relevance

There is a need to correctly describe the biochemistry of child development as well as to identify strategies to develop accurate and consistent pediatric reference intervals for improved pediatric care.

Comparison of Cystatin C and Creatinine-Based Equations with Measured Glomerular Filtration Rate in a Diverse Pediatric Population

BACKGROUND

Accurate assessment of kidney function is essential for early detection of kidney damage. While measured glomerular filtration rate (mGFR) is occasionally used as a reference, estimated GFR (eGFR) from serum creatinine- and cystatin C (CysC)-based equations are routinely used in clinical practice as a reliable and less invasive approach. In pediatric populations, CysC-based equations provide a closer approximation as they are independent of body composition. Limited information is available on the performance of CysC-based equations in comparison with mGFR with tracers other than iohexol. Therefore, the goal of our study was to evaluate how eGFR, based on several CysC- and creatinine-based equations, with and without race correction, relates to mGFR in a diverse pediatric population.

METHODS

A total of 43 patients (7 months to 21 years) from diverse race/ethnicity were retrospectively studied to compare the mGFR from multiple blood sample collections after intravenous tracer injection (Tc-99mDTPA) with eGFR using 9 equations. Deming regression analyses were performed to assess correlation between the mGFR and eGFRs.

RESULTS

The average mGFR for this cohort was 95.0 mL/min/1.73 m2. Race-corrected (RC) equations gave overestimated eGFR across all ethnic groups, with the lowest bias for Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) CysC-creatinine (34.14 mL/min/1.73 m2). The best correlations to mGFR, percentage of eGFR within 30% of mGFR (P30), and lowest biases were from non-race-corrected (NRC) equations Chronic Kidney Disease in Children (CKiD) (0.6460, 65.1%, 2.86 mL/min/1.73 m2), CKD-EPI CysC (0.6858, 69.8%, 11.01 mL/min/1.73 m2), and Schwartz CysC (0.6876, 79.1%, -14.00 mL/min/1.73 m2).

CONCLUSION

Overall, CysC-based equations without race correction provide a good approximation of mGFR and a less invasive alternative to monitoring kidney function in pediatric population, irrespective of race/ethnicity.

Evaluation of novel glomerular filtration rate estimation equations in adolescents and young adults with type 1 diabetes

AIMS

Individuals with type 1 diabetes (T1D) are at an increased risk of chronic kidney disease making estimation of glomerular filtration rate (eGFR) an important component of diabetes care. Which eGFR equation is most appropriate to use in patients with T1D during the transition to adult care is unclear. We, therefore, sought to evaluate the performance of five eGFR equations in adolescents and young adults with T1D.

METHODS

Measured iohexol-based glomerular filtration rate was compared to the Chronic Kidney Disease and Epidemiology Collaboration (CKD-EPI) eGFR, Chronic Kidney Disease in Children (CKiD) eGFR, and three recently developed age-adjusted versions of these in 53 patients with T1D and preserved GFR using bias, precision, and accuracy.

RESULTS

The best performance was found in the sex-dependent CKiD equation (bias: -0.8, accuracy: 11.8 ml/min/1.73 m²). Bias and accuracy (26.4 and 26.8 ml/min/1.73 m²) were worst in the CKD-EPI equation. Age-dependent adjustment improved performance for this equation (bias: 5.3, accuracy: 13.4 ml/min/1.73 m²), but not for the CKiD equation (bias: 15.5, accuracy: 18.8 ml/min/1.73 m²).

CONCLUSION

Age-adjustment improved performance for the CKD-EPI equation, but not for the CKiD equation. The sex-adjusted CKiD equation performed best out of all equations.

Accuracy of single intravenous access iohexol GFR in children is hampered by marker contamination

Measurement of glomerular filtration rate (GFR) in children by iohexol injection and blood sampling from the contralateral arm is widely used. A single intravenous access for iohexol injection and subsequent blood sampling has the obvious advantages of being less painful and easier to perform. The purpose of our study was to determine if blood samples drawn from the injection access are feasible and accurate for iohexol GFR (iGFR) measurements. Thirty-one children, median age 10.5 (range 6–17) years, with chronic kidney disease were given a bolus of iohexol followed by extended saline flushing and subsequent venous blood samples collected from the injection access as well as from a cannula in the contralateral arm, the latter serving as the reference method. Paired venous blood samples were collected at four time points (2, 3, 3.5 and 4 h) after the iohexol bolus. Blood sample discarding preceded and saline flushing followed each blood sampling to avoid marker contamination. iGFR based on samples drawn from the injection access at 2 and 3 h showed significantly lower iGFR than measurement from the contralateral arm (p < 0.01). Singlepoint iGFR did not differ significantly after 3–4 repeated procedures of blood discarding and saline flusing (3.5 and 4 h). Despite thorough saline flushing there is still a relatively high risk of falsely low iGFR due to marker contamination in blood samples from the injection site. Hence, blood sampling from a second intravenous access is recommended for routine iohexol GFR measurements in children.

Clinical trial registration: ClinicalTrials.gov, Identifier NCT01092260, https://clinicaltrials.gov/ct2/show/NCT01092260?term=tondel&rank=2.

Distribution of creatinine and estimated glomerular filtration rate in healthy schoolchildren: The Health Oriented Pedagogical Project (HOPP)

Glomerular filtration rate (GFR) measured by urinary clearance of inulin is considered the gold standard for assessment of kidney function in both adults and children. Because the procedure is cumbersome, GFR is estimated (eGFR) using algorithms based on the observed relationship between measured GFR (mGFR) and more accessible biomarkers such as creatinine and cystatin C. In children, most of the data on this relationship is retrieved from patients with reduced kidney function. Nonetheless, eGFR equations are widely in use in healthy children to evaluate kidney status and diagnose kidney disease. The aim of the present study was to compare the distribution of eGFR using two established pediatric eGFR equations incorporating age, height and serum creatinine (Schwartz-Lyon and Full Age Spectrum-height) and two recently published equations restricted to age and serum creatinine (Lund-Malmö Revised 18 and European Kidney Function Consortium equation) in 1200 healthy schoolchildren age 6-12 years. In addition, we present 2.5^th, median and 97.5^th percentiles for serum creatinine stratified by age and gender. Depending on the equation used, mean eGFR ranged from 101.6 to 115.4 mL/min/1.73 m². The lower 2.5^th percentile ranged from 83.3 to 89.0 mL/min/1.73 m² and the fraction of children with eGFR < 90 mL/min/1.73 m² ranged from 2.9% to 9.8%. In conclusion, expected values of eGFR in healthy children are significantly dependent on the equation used. When decision limits for diagnosis or classification are applied to eGFR results, the related equation should be clearly stated.

Comparison of Renal Stones and Nephrocalcinosis in Children: Findings From Two Tertiary Centers in Saudi Arabia

Background: Renal stones (nephrolithiasis and urolithiasis) and nephrocalcinosis are uncommon in children; however, their incidences in pediatric populations have been increasing. Patients and Methods: This multicenter retrospective study compared the clinical presentation, etiology, and outcomes of childhood nephrolithiasis or urolithiasis with those of nephrocalcinosis. Results: The study included 144 children: 93 with renal stones and 51 with nephrocalcinosis. The mean age at presentation was 72 months and 54 months for children with renal stones and nephrocalcinosis, respectively. A history of consanguinity was found in 65% and 76% of the cases of renal stones and nephrocalcinosis, respectively. Congenital anomalies of the kidneys and urinary tract (CAKUT) were present in 28 and 9.8% of the patients with renal stones and nephrocalcinosis, respectively. The most common symptoms of renal stones were flank pain (29%), hematuria (15%), and dysuria (11%). Urinary tract infection was the primary presentation in the nephrocalcinosis group (18%), followed by failure to thrive (16%), polyuria (12%), and dehydration (12%). The majority of renal stone cases were caused by metabolic disorders, including hyperoxaluria (18%), cystinuria (18%), hypercalciuria (12%), and hyperuricosuria (2%). In contrast, the most common underlying disorders in cases of nephrocalcinosis were familial hypomagnesemia, hypercalciuria, nephrocalcinosis (35%), distal renal tubular acidosis (23%), and Bartter syndrome (6%). Clinical outcomes were significantly better in children with nephrolithiasis/urolithiasis than in those with nephrocalcinosis, who showed radiological evidence of worsening/persistent calcinosis and progressed more frequently to chronic kidney disease (stage II-IV) and end-stage kidney disease. Conclusion: The average age at presentation for children with renal stones was greater than that for those presenting with nephrocalcinosis. More than 25% of the children with renal stones were found to have CAKUT. Nephrocalcinosis was associated with worse clinical outcomes related to kidney function and disease resolution than nephrolithiasis.

Cystatin C as a biomarker of chronic kidney disease: latest developments

INTRODUCTION

Chronic kidney disease (CKD) is common, occurring in over 10% of individuals globally, and is increasing in prevalence. The limitations of traditional biomarkers of renal dysfunction, such as serum creatinine, have been well demonstrated in the literature. Therefore, augmenting clinical assessment with newer biomarkers, such as serum cystatin C, has the potential to improve disease monitoring and patient care.

AREAS COVERED

The present paper assesses the utility and limitations of serum cystatin C as a biomarker for CKD in light of the current literature.

EXPERT OPINION

Serum cystatin C has been well established as an early and accurate biomarker of CKD that is particularly helpful in patients for whom creatinine is an inadequate marker or for whom more cumbersome methods of glomerular filtration rate (GFR) measurement are impractical. Current research questions are no longer focused on if, but rather when and how often cystatin C should be used in the evaluation of CKD patients. However, transition of all reagents and estimated GFR equations to the newly established International Standard is critical for developing generalizable data.

Prescribing peritoneal dialysis for high-quality care in children

Background:

Peritoneal dialysis (PD) remains the most widely used modality for chronic dialysis in children, particularly in younger children and in lower and middle income countries (LMICs). We present guidelines for dialysis initiation, modality selection, small solute clearance, and fluid removal in children on PD. A review of the literature and key studies that support these statements are presented.

Methods:

An extensive Medline search for all publications on PD in children was performed using predefined search criteria.

Results:

High-quality randomized trials in children are scarce and current clinical practice largely relies on data extrapolated from adult studies or drawn from observational cohort studies in children. The evidence and strength of the recommendation is GRADE-ed, but in the absence of high-quality evidence, the opinion of the authors is provided and must be carefully considered by the treating physician, and adapted to local expertise and individual patient needs as appropriate. We discuss the timing of dialysis initiation, factors to be considered when selecting a dialysis modality, the assessment and management of volume status on PD, achieving optimal small solute clearance, and the importance of preserving residual kidney function. While optimal dialysis must remain the goal for every patient, a careful discussion with fully informed patients and caregivers is important to understand the patient and family’s expectations of dialysis and reasonable adjustments to the dialysis program may be considered in accordance with a philosophy of shared decision-making.

Conclusions:

There continues to be very poor evidence in the field of chronic PD in children and these recommendations can at best serve to guide clinical decision-making. In LMICs, every effort should be made to conform to the framework of these statements, taking into account resource limitations.

The role of urinary NGAL and serum cystatin C in assessing the severity of ureteropelvic junction obstruction in infants

BACKGROUND

The ideal management of ureteropelvic junction obstruction (UPJO) remains debatable. This prospective case-control study aimed to investigate if urinary levels of Neutrophil Gelatinase-Associated Lipocalin (NGAL) and serum levels of cystatin C could distinguish surgical from non-surgical cases of UPJO and if they could detect earlier impairment of renal function.

METHODS

Biomarkers were measured in the following age-matched groups: (a) 22 infants with surgical UPJO, at initial diagnosis and 12 months postoperatively (groups A1 and A2, respectively); (b) 19 infants with non-surgical UPJO (group B); and (c) 17 controls (group C). Based on serum cystatin C levels, estimated glomerular filtration rate (eGFR) was calculated.

RESULTS

Urinary NGAL (uNGAL) was significantly higher in group A1 vs. group A2 (p = 0.02) and in group A1 vs. group C (p = 0.03), whereas there was no statistically significant difference between groups A2 and C (p = 0.77). Likewise, cystatin C levels were significantly higher in group A1 vs. group A2 and in group A1 vs. group C (p = 0.004 and p = 0.02, respectively), but no statistically significant difference between groups A2 and C (p = 0.82). uNGAL and serum cystatin C did not differ between groups B and A, nor did they differ between groups B and C. Cystatin C levels and eGFR of group A1 were significantly higher than those of group A2 and group C (p = 0.0001 and p = 0.02, respectively).

CONCLUSION

It seems that NGAL and cystatin C are able to distinguish patients who were treated surgically from healthy controls, and their levels appear to improve significantly following surgery.

European consensus-based recommendations for diagnosis and treatment of immunoglobulin A vasculitis—the SHARE initiative

Objectives

IgA vasculitis (IgAV, formerly known as Henoch–Schönlein purpura) is the most common cause of systemic vasculitis in childhood. To date, there are no internationally agreed, evidence-based guidelines concerning the appropriate diagnosis and treatment of IgAV in children. Accordingly, treatment regimens differ widely. The European initiative SHARE (Single Hub and Access point for paediatric Rheumatology in Europe) aims to optimize care for children with rheumatic diseases. The aim therefore was to provide internationally agreed consensus recommendations for diagnosis and treatment for children with IgAV.

Methods

Recommendations were developed by a consensus process in accordance with the EULAR standard operating procedures. An extensive systematic literature review was performed, and evidence-based recommendations were extrapolated from the included papers. These were evaluated by a panel of 16 international experts via online surveys and subsequent consensus meeting, using nominal group technique. Recommendations were accepted when ⩾80% of experts agreed.

Results

In total, 7 recommendations for diagnosis and 19 for treatment of paediatric IgAV were accepted. Diagnostic recommendations included: appropriate use of skin and renal biopsy, renal work-up and imaging. Treatment recommendations included: the importance of appropriate analgesia and angiotensin-converting enzyme inhibitor use and non-renal indications for CS use, as well as a structured approach to treating IgAV nephritis, including appropriate use of CS and second-line agents in mild, moderate and severe disease along with use of angiotensin-converting enzyme inhibitors and maintenance therapy.

Conclusion

The SHARE initiative provides international, evidence-based recommendations for the diagnosis and treatment of IgAV that will facilitate improvement and uniformity of care.