Estimating glomerular filtration rate in children at serial follow-up when height is unknown

Evaluation of glomerular filtration rate estimation equations based on serum creatinine in healthy Chinese children and adolescents: a nationwide cross-sectional study

BACKGROUND

Several equations for glomerular filtration rate (GFR) estimation based on serum creatinine (SCr) have been proposed for children, but most were developed among patients with kidney disease. The association between SCr and GFR may be distorted by kidney dysfunction and thus not applicable to healthy children. This study aimed to evaluate the applicability of existing SCr-based GFR estimation equations in healthy Chinese children.

METHODS

GFR estimation equations that developed in healthy children were mainly analysed, including the Flanders Metadata (FM), simple height-independent (Simple), full age spectrum (FAS) and FAS-height equations. The FM equation assumed that GFR is proportional to the ratio of height to SCr. The Simple, FAS and FAS-height equations assumed that the ratio of GFR to population mean is equal to the reciprocal ratio of SCr to population mean (denoted by Q). Estimated GFR were calculated using data of SCr, age, sex and height collected from 12 208 healthy Chinese children aged 3 months to <20 years. The performance of GFR estimation equations was evaluated by the sex and age distribution of the estimated GFR and the deviation from the measured GFR reported by other literatures.

RESULTS

The FM and Simple equations performed well in their applicable age of 1 month to 14 years, but presented undesirable sex difference after adolescence. The FAS and FAS-height equations showed reasonable development trend of estimated GFR throughout childhood, and the FAS equation had higher consistency than the FAS-height equation compared with measured GFR in healthy children. The GFR estimated by the FAS equation increased with age before 2 years, and reached the adult level thereafter without important sex difference.

CONCLUSIONS

The FAS equation is applicable to healthy Chinese children.

KIdney aNd blooD prESsure ouTcomes in Childhood Cancer Survivors: Description of Clinical Research Protocol of the KINDEST-CCS Study

Background

Approximately 30% of childhood cancer survivors (CCSs) will develop chronic kidney disease (CKD) or hypertension 15 to 20 years after treatment ends. The incidence of CKD and hypertension in the 5-year window after cancer therapy is unknown. Moreover, extent of monitoring of CCS with CKD and associated complications in current practice is underexplored. To inform the development of new and existing care guidelines for CCS, the epidemiology and monitoring of CKD and hypertension in the early period following cancer therapy warrants further investigation.

Objective

To describe the design and methods of the KIdney aNd blooD prESsure ouTcomes in Childhood Cancer Survivors study, which aims to evaluate the burden of late kidney and blood pressure outcomes in the first ~10 years after cancer therapy, the extent of appropriate screening and complications monitoring for CKD and hypertension, and whether patient, disease/treatment, or system factors are associated with these outcomes.

Design

Two distinct, but related studies; a prospective cohort study and a retrospective cohort study.

Setting

Five Ontario pediatric oncology centers.

Patients

The prospective study will involve 500 CCS at high risk for these late effects due to cancer therapy, and the retrospective study involves 5,000 CCS ≤ 18 years old treated for cancer between January 2008 and December 2020.

Measurements

Chronic kidney disease is defined as Estimated glomerular filtration rate <90 mL/min/1.73 m² or albumin-to-creatinine ratio ≥ 3mg/mmol. Hypertension is defined by 2017 American Academy of Pediatrics guidelines.

Methods

Prospective study: we aim to investigate CKD and hypertension prevalence and the extent to which they persist at 3- and 5-year follow-up in CCS after cancer therapy. We will collect detailed biologic and clinical data, calculate CKD and hypertension prevalence, and progression at 3- and 5-years post-therapy. Retrospective study: we aim to investigate CKD and hypertension monitoring using administrative and health record data. We will also investigate the validity of CKD and hypertension administrative definitions in this population and the incidence of CKD and hypertension in the first ~10 years post-cancer therapy. We will investigate whether patient-, disease/treatment-, or system-specific factors modify these associations in both studies.

Limitations

Results from the prospective study may not be generalizable to non-high-risk CCS. The retrospective study is susceptible to surveillance bias.

Conclusions

Our team and knowledge translation plan is engaging patient partners, researchers, knowledge users, and policy group representatives. Our work will address international priorities to improve CCS health, provide the evidence of new disease burden and practice gaps to improve CCS guidelines, implement and test revised guidelines, plan trials to reduce CKD and hypertension, and improve long-term CCS health.

Acute kidney injury during cisplatin therapy and associations with kidney outcomes 2 to 6 months post-cisplatin in children: a multi-centre, prospective observational study

BACKGROUND

Few studies describe acute kidney injury (AKI) burden during paediatric cisplatin therapy and post-cisplatin kidney outcomes. We determined risk factors for and rate of (1) AKI during cisplatin therapy, (2) chronic kidney disease (CKD) and hypertension 2-6 months post-cisplatin, and (3) whether AKI is associated with 2-6-month outcomes.

METHODS

This prospective cohort study enrolled children (aged < 18 years at cancer diagnosis) treated with cisplatin from twelve Canadian hospitals. AKI during cisplatin therapy (primary exposure) was defined based on Kidney Disease: Improving Global Outcomes (KDIGO) serum creatinine criteria (≥ stage one). Severe electrolyte abnormalities (secondary exposure) included ≥ grade three hypophosphatemia, hypokalemia, or hypomagnesemia (National Cancer Institute Common Terminology Criteria for Adverse Events v4.0). CKD was albuminuria or decreased kidney function for age (KDIGO guidelines). Hypertension was defined based on the 2017 American Academy of Pediatrics guidelines.

RESULTS

Of 159 children (median [interquartile range [IQR]] age: 6 [2-12] years), 73/159 (46%) participants developed AKI and 55/159 (35%) experienced severe electrolyte abnormalities during cisplatin therapy. At median [IQR] 90 [76-110] days post-cisplatin, 53/119 (45%) had CKD and 18/128 (14%) developed hypertension. In multivariable analyses, AKI was not associated with 2-6-month CKD or hypertension. Severe electrolyte abnormalities during cisplatin were associated with having 2-6-month CKD or hypertension (adjusted odds ratio (AdjOR) [95% CI]: 2.65 [1.04-6.74]). Having both AKI and severe electrolyte abnormalities was associated with 2-6-month hypertension (AdjOR [95% CI]: 3.64 [1.05-12.62]).

CONCLUSIONS

Severe electrolyte abnormalities were associated with kidney outcomes. Cisplatin dose optimization to reduce toxicity and clear post-cisplatin kidney follow-up guidelines are needed. A higher resolution version of the Graphical abstract is available as Supplementary information.

Defining pediatric community-acquired acute kidney injury: an observational study

BACKGROUND

Pediatric acute kidney injury (AKI) is associated with long-term morbidity and mortality; however, outcomes improve when AKI is detected earlier. Current definitions of AKI use baseline creatinine; community-acquired AKI (CA-AKI) is difficult to define and detect in the pediatric emergency department (ED) when no baseline creatinine is available. Our objective was to compare age- and gender-based creatinine norms to the traditional baseline (lowest creatinine in previous 3 months) to diagnose CA-AKI.

METHODS

This was a retrospective cross-sectional study conducted in children 1 month-18 years of age seen in the pediatric ED in whom a creatinine was obtained.

RESULTS

Per the Kidney Disease Improving Global Outcomes AKI definition in encounters with baseline creatinine available, 343/2338 (14.7%) had CA-AKI. When the upper limit of the age- and gender-based creatinine norm was applied as a surrogate baseline creatinine, CA-AKI was diagnosed in 1.5% of encounters (239/15,486). Additionally, CA-AKI was diagnosed in 178 cases using the upper limit of age- and gender-based creatinine norms only, as these cases did not have a baseline creatinine.

CONCLUSIONS

Age- and gender-based creatinine norms can be applied as a surrogate baseline to detect CA-AKI in all children regardless of whether baseline creatinine is available, potentially detecting it earlier.

A prospective multi-center quality improvement initiative (NINJA) indicates a reduction in nephrotoxic acute kidney injury in hospitalized children

Nephrotoxic medication (NTMx) exposure is a common cause of acute kidney injury (AKI) in hospitalized children. The Nephrotoxic Injury Negated by Just-in time Action (NINJA) program decreased NTMx associated AKI (NTMx-AKI) by 62% at one center. To further test the program, we incorporated NINJA across nine centers with the goal of reducing NTMx exposure and, consequently, AKI rates across these centers. NINJA screens all non-critically ill hospitalized patients for high NTMx exposure (over three medications on the same day or an intravenous aminoglycoside over three consecutive days), and then recommends obtaining a daily serum creatinine level in exposed patients for the duration of, and two days after, exposure ending. Additionally, substitution of equally efficacious but less nephrotoxic medications for exposed patients starting the day of exposure was recommended when possible. The main outcome was AKI as defined by the Kidney Disease Improving Global Outcomes (KDIGO) serum creatinine criteria (increase of 50% or 0.3 mg/dl over baseline). The primary outcome measure was AKI episodes per 1000 patient-days. Improvement was defined by statistical process control methodology and confirmed by Autoregressive Integrated Moving Average (ARIMA) modeling. Eight consecutive bi-weekly measure rates in the same direction from the established baseline qualified as special cause change for special process control. We observed a significant and sustained 23.8% decrease in NTMx-AKI rates by statistical process control analysis and by ARIMA modeling; similar to those of the pilot single center. Thus, we have successfully applied the NINJA program to multiple pediatric institutions yielding decreased AKI rates.

Comparison of methods to estimate glomerular filtration rate in paediatric oncology patients

AIMS

Glomerular filtration rate (GFR) is estimated daily in paediatric oncology patients; however, few equations, particularly ones that do not include serum creatinine, have been evaluated in this population. We aimed to compare the predictive performance of different equations available to estimate GFR in paediatric oncology patients.

METHODS

GFR was measured (mGFR) in paediatric oncology patients based on a chromium 51-labeled ethylene diamine tetraacetic acid excretion test. GFR was estimated (eGFR) in these same patients using equations identified from the literature. mGFR and eGFR values were compared, and the predictive performance of various eGFR equations was assessed in terms of their bias, precision and accuracy.

RESULTS

In total, 124 mGFR values ranging from 7 to 146 mL/min were available for analysis from 73 children. Twenty-two equations were identified from the literature. The Flanders metadata equation displayed the lowest absolute bias (mean error of 0.9 mL/min) and the greatest precision (root mean square error of 13.1 mL/min). The univariate Schwartz equation predicted the highest percentage (81.5%) of eGFR values within 30% of mGFR values, and the Rhodin fat-free mass equation predicted the highest percentage (37.1%) of eGFR values within 10% of mGFR values.

CONCLUSIONS

A number of equations were identified that could be used to estimate renal function in paediatric oncology patients; however, none was found to be highly accurate. The Flanders metadata equation and univariate Schwartz performed the best in this study, and we would suggest that these two equations may be used cautiously in paediatric oncology patients for clinical decision making, understanding their limitations.

Validation of serum creatinine-based formulae in pediatric renal transplant recipients

BackgroundAccurate monitoring of kidney function is important post-renal transplant; however, the routine use of measured glomerular filtration rate (GFR) or addition of newer serum markers is prohibitively expensive for routine clinical use, especially in children. We validated the modified Schwartz formula in pediatric renal transplant recipients across a range of demographic and clinical characteristics.MethodsIn a retrospective cohort study with nested cross-sectional analysis, we compared 505 measurements of estimated GFR using serum creatinine to simultaneous diethylenetriaminepentaacetic acid (DTPA) nuclear GFR (nGFR) measurements from 173 pediatric kidney transplant recipients who were < 18 years of age from 1 January 2001 to 31 December 2012 accounting for repeated measures.ResultsAmong 173 children, 62% were males, 85% with nGFR of ≥60 ml/min/1.73 m², and the median age at transplant was 13.6 years (interquartile range 8.3-16 years). Overall, the modified Schwartz and Pottel formulae had better bias (0.07 and -0.03 ml/min/1.73 m², respectively) and accuracy within 30% (both 84.4%) in comparison to Lyon and Zappitelli formulae. The 30% accuracy varied for girls and children <5 and >15 years.ConclusionModified Schwartz is a practical, non-invasive, and a valid bedside tool that provides a valid measurement of GFR in pediatric kidney transplant recipients.

Measuring and estimating glomerular filtration rate in children

Glomerular filtration rate (GFR) is the best index for kidney function in health and disease. Knowledge of the GFR is essential for the detection (diagnosis) and monitoring of renal function during disease progression and for ensuring correct medication doses. Inulin clearance (plasma or urine) is currently considered to be the gold standard for measuring GFR, but in clinical practice the measurement of other exogenous filtration markers from the plasma often replaces that of inulin clearance. Different protocols can be used to determine the area under the plasma disappearance curve, and an understanding of these methods is important. GFR can also be estimated by GFR equations (eGFR), which are most often used in clinical practice because they only require a knowledge of the serum creatinine or cystatin C level and demographic information. eGFR equations are easy to use but they do have their limitations, and it is important to know how these equations were derived and in which circumstances they can be used most accurately. The aim of this review is to explain how GFR can be measured using the renal clearance and the plasma clearance method and which eGFR equations can be applied to children, as well as how and when these equations can be used in clinical practice.

Pottels Equation for Estimation of Glomerular Filtration Rate

The retrospective study was carried out to examine performance of Pottels height- independent equation compared to Schwartzs height-dependent equation to estimate glomerular filtration rate in 115 children in Indian setting. The Pottels equation performed well compared to updated Schwartz equation (R2=0.94, mean bias 0.25, 95% LOA=20.4, -19.9). The precision was better at lower range of estimated GFR.

Prevalence and Severity of Anemia in Children Hospitalized with Acute Heart Failure

OBJECTIVE

Anemia is common among adult heart failure patients and is associated with adverse outcomes, but data are lacking in children with heart failure. The purpose of this study was to determine the prevalence of anemia in children hospitalized with acute heart failure and to evaluate the association between anemia and adverse outcomes.

DESIGN

Review of the medical records of 172 hospitalizations for acute heart failure.

SETTING

Single, tertiary children's hospital.

PATIENTS

All acute heart failure admissions to our institution from 2007 to 2012.

INTERVENTIONS

None.

OUTCOME MEASURES

Composite endpoint of death, mechanical circulatory support deployment, or cardiac transplantation.

RESULTS

Patients ages ranged in age from 4 months to 23 years, with a median of 7.5 years, IQR 1.2, 15.9. Etiologies of heart failure included: dilated cardiomyopathy (n = 125), restrictive cardiomyopathy (n = 16), transplant coronary artery disease (n = 18), ischemic cardiomyopathy (n = 7), and heart failure after history of congenital heart disease (n = 6). Mean hemoglobin concentration at admission was 11.8 g/dL (±2.0 mg/dL). Mean lowest hemoglobin prior to outcome was 10.8 g/dL (±2.2 g/dL). Anemia (hemoglobin <10 g/dL) was present in 18% of hospitalizations at admission and in 38% before outcome. Anemia was associated with increased risk of death, transplant, or mechanical circulatory support deployment (adjusted odds ratio 1.79, 95% confidence interval = 1.12-2.88, P = .011). For every 1 g/dL increase in the patients' lowest hemoglobin during admission, the odds of death, transplant, or mechanical circulatory support deployment decreased by 18% (adjusted odds ratio = 0.82, 95% confidence interval = 0.74-0.93, P = 0.002).

CONCLUSIONS

Anemia occurs commonly in children hospitalized for acute heart failure and is associated with increased risk of transplant, mechanical circulatory support, and inhospital mortality.

Modification of the Schwartz equations for children increases their accuracy at eGFR > 60 mL/min/1.73 m(2)

AIM

Estimation of eGFR in children with normal kidney function using the Schwartz equations results in underestimating real GFR.

MATERIALS AND METHODS

We propose modification of three Schwartz equations - two based on creatinine concentration (eGFRScrBS bedside) and (eGFRScr) and one 3-marker based on creatinine, urea and cystatin C concentrations (eGFRS3M). The iohexol test (reference method) was performed 417 times in 353 children >2 years with mean GFR: 98 ± 31.6 ml/min/1.73m(2). The assessment included also the Filler and Zappitelli equations. The modification was performed using methods: (1) based on equation, eGFRcor = a [eGFR - T] + T, where T = 50, if eGFR > T, and a equals for: eGFRScrBS 1.4043, for eGFRScr 2.0048, for eGFRS3M 1.2951, and (2) based on correction of all coefficients of the original equation.

RESULTS

For comparison of all the results and for children with GFR< 60, 60-90, 90-135 and > 135 ml/min/1.73m(2) the correlation coefficient, relative error (RE) and root mean square relative error (RMSRE) was employed and revealed improvement of RE from 25.9 to 6.8 and 3.9% (depending on the correction method) for eGFRScr; from 19 to 8.1 and 3.9% for eGFRScrBS and: from 11.6% to 2.0 and 2.3% for eGFRS3M (respectively). The RMSRE values changed from 30 to 21.3 and 19.8% for eGFRScr, from 25.1 to 21.6 and 19.8% for eGFRScrBS and from 19.1 to 15.8 and 15.3 % for eGFRS3M.

CONCLUSIONS

Modifications of Schwartz equations at GFR > 60 ml/min/1.73m(2) significantly improves the accuracy of calculating eGFR. The 3-markers equation is more accurate and should be employed frequently.

An estimated glomerular filtration rate equation for the full age spectrum

BACKGROUND

Glomerular filtration rate (GFR) is accepted as the best indicator of kidney function and is commonly estimated from serum creatinine (SCr)-based equations. Separate equations have been developed for children (Schwartz equation), younger and middle-age adults [Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation] and older adults [Berlin Initiative Study 1 (BIS1) equation], and these equations lack continuity with ageing. We developed and validated an equation for estimating the glomerular filtration rate that can be used across the full age spectrum (FAS).

METHODS

The new FAS equation is based on normalized serum creatinine (SCr/Q), where Q is the median SCr from healthy populations to account for age and sex. Coefficients for the equation are mathematically obtained by requiring continuity during the paediatric-adult and adult-elderly transition. Research studies containing a total of 6870 healthy and kidney-diseased white individuals, including 735 children, <18 years of age, 4371 adults, between 18 and 70 years of age, and 1764 older adults, ≥70 years of age with measured GFR (inulin, iohexol and iothalamate clearance) and isotope dilution mass spectrometry-equivalent SCr, were used for the validation. Bias, precision and accuracy (P30) were evaluated.

RESULTS

The FAS equation was less biased [-1.7 (95% CI -3.4, -0.2) versus 6.0 (4.5, 7.5)] and more accurate [87.5% (85.1, 89.9) versus 83.8% (81.1, 86.5)] than the Schwartz equation for children and adolescents; less biased [5.0 (4.5, 5.5) versus 6.3 (5.9, 6.8)] and as accurate [81.6% (80.4, 82.7) versus 81.9% (80.7, 83.0)] as the CKD-EPI equation for young and middle-age adults; and less biased [-1.1 (-1.6, -0.6) versus 5.6 (5.1, 6.2)] and more accurate [86.1% (84.4, 87.7) versus 81.8% (79.7, 84.0)] than CKD-EPI for older adults.

CONCLUSIONS

The FAS equation has improved validity and continuity across the full age-spectrum and overcomes the problem of implausible eGFR changes in patients which would otherwise occur when switching between more age-specific equations.

The impact of estimated glomerular filtration rate equations on chronic kidney disease staging in pediatric renal or heart transplant recipients

BACKGROUND

The aim of this study was to evaluate the performance of selected pediatric estimated glomerular filtration rate (eGFR) equations in relation to the clinical management of children after renal or heart transplantation or post-chemotherapy treatment.

METHODS

This study was a retrospective cross-sectional analysis of 61 children whose glomerular function (GFR) had been determined using a single-dose inulin clearance (iGFR) method. Eight equations for estimating the GFR were evaluated for bias, agreement, accuracy, and clinical stratification.

RESULTS

The outcome of all eight eGFR equations differed from the value determined using the iGFR method, with the mean bias ranging from -3.4 to 20.7 ml/min/1.73 m(2) and 90 % accuracy ranging from 16 to 26 %. All eGFR equations overestimated renal function in patients with decreased kidney function as determined by the iGFR method and underestimated renal function in patients with normal kidney function. Consequently, based on the eGFR values, patients with low GFR values according to the iGFR method were staged in a less severe chronic kidney disease (CKD) category, and patients with normal GFR values according to the iGFR method were staged in a more severe CKD category. The percentage of correctly classified patients ranged from 32.6 to 41.6 %.

CONCLUSIONS

In our cohort we found the CKiDIII equation to be the best alternative to calculating the GFR using the inulin clearance method, closely followed by the Hoste and the revised Grubb equations. The performances of all eight eGFR equations assessed were moderate at best and only slightly better than the easy-to-do bedside Schwartz equation.

Estimation of glomerular filtration rate with and without height: effect of age and renal function level

BACKGROUND

The current glomerular filtration rate (GFR) equation (CKiD) may be less accurate in adolescents and children with higher GFR.

METHODS

This was a retrospective study (n = 161, 247 (99)mTc DTPA-GFRs). Six equations were evaluated for bias, accuracy, and low GFR diagnosis: (1) CKiD; (2) historic center; (3) Hoste(age); (4) Hoste(height); (5) modified Pottel; (6) Gao. Children with ≥ vs. <90 ml/min/1.73 m(2)) and < vs. ≥16 years were compared. Two adult equations were evaluated in children ≥16 years.

RESULTS

Most equations underestimated GFR by 1-14 % in the higher GFR group, least so for Hoste(age). In the low GFR group, Hoste(age) and historic center overestimated GFR significantly more than CKiD (p < 0.05). Accuracy (within 30 % GFR) was similar across equations and GFR subgroups (66-86 %). In the ≥16 years group, CKiD underestimated GFR by ∼10 %, vs. ∼3 % for Hoste(height). Accuracy was 5-10 % lower in the older group and most equations were more sensitive than specific for detecting low GFR; this discrepancy was less for the Hoste equations. Adult equations were highly inaccurate.

CONCLUSIONS

GFR estimation in older children and with higher GFR is suboptimal. The Hoste(height) may be an alternative GFR estimation method; Hoste(age) may allow for height-independent GFR estimation in patients with normal GFR.

Height-independent estimation of glomerular filtration rate in children: an alternative to the Schwartz equation

OBJECTIVE

To compare the diagnostic performance of 2 height-independent equations used to calculate estimated glomerular filtration rate (eGFR), those of Pottel (eGFR-Pottel) and the British Columbia Children's Hospital (BCCH) (eGFR-BCCH), with the commonly used Schwartz equation (eGFR-Schwartz).

STUDY DESIGN

We externally validated eGFR-Pottel and eGFR-BCCH in a well-characterized pediatric patient population (n = 152) and compared their diagnostic performance with that of eGFR-Schwartz using Bland-Altman analysis. All patients underwent glomerular filtration rate measurement using the gold standard single-injection inulin clearance method (GFR-inulin).

RESULTS

Median GFR-inulin was 92.0 mL/min/1.73 m² (IQR, 76.1-107.4 mL/min/1.73 m²). Compared with GFR-inulin, the mean bias for eGFR-Schwartz was -10.1 mL/min/1.73 m(2) (95% limits of agreement [LOA], -77.5 to 57.2 mL/min/1.73 m(2)), compared with -12.3 mL/min/1.73 m² (95% LOA, -72.6 to 47.9 mL/min/1.73 m(2)) for eGFR-Pottel and -22.1 mL/min/1.73 m² (95% LOA, -105.0 to 60.8 mL/min/1.73 m(2)) for eGFR-BCCH. eGFR-Pottel showed comparable accuracy to eGFR-Schwartz, with 77% and 76% of estimates within 30% of GFR-inulin, respectively. eGFR-BCCH was less accurate than eGFR-Schwartz (66% of estimates within 30% of GFR-inulin; P < .01).

CONCLUSION

The performance of eGFR-Pottel is superior to that of eGFR-BCCH and comparable with that of eGFR-Schwartz. eGFR-Pottel is a valid alternative to eGFR-Schwartz in children and could be reported by the laboratory if height data are not available.

A simple height-independent equation for estimating glomerular filtration rate in children

BACKGROUND

The chronic kidney disease (CKD) classification system for children is similar to the CKD classification system for adults, using estimated glomerular filtration rate (eGFR) combined with fixed cut-off values of 60, 30, and 15 ml/min/1.73 m(2) for CKD stages III, IV, and V, respectively. To estimate GFR in children, eGFR-equations are used that require serum creatinine (Scr), but also height information, which is normally not available in clinical laboratory databases.

METHODS

This retrospective study is based on data from two different databases, one that has previously been used to develop the Flanders Metadata equation for children and one database including 353 children who underwent (51)Cr-EDTA GFR, serum creatinine, height, and weight measurements.

RESULTS

A height-independent eGFR equation based on the concept of a population-normalized Scr, presented before for adults, is extended to children: eGFR = 107.3/(Scr/Q), with Q the median Scr for healthy children of a particular age. This equation is validated against direct measurements of GFR, and against the updated Schwartz and Flanders Metadata equation.

CONCLUSIONS

The new simple height-independent equation performs very well and should make (mass) screening of kidney function in children easier.