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Abstract: SA-PO587

Hyperfiltration and eGFR Equations in the Pediatric NEPTUNE Study Cohort

Session Information

  • Pediatric Nephrology - II
    November 05, 2022 | Location: Exhibit Hall, Orange County Convention Center‚ West Building
    Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

  • 1800 Pediatric Nephrology

Authors

  • Salmon, Eloise, University of Michigan, Ann Arbor, Michigan, United States
  • Wang, Yujie, University of Michigan, Ann Arbor, Michigan, United States
  • Dell, Katherine MacRae, Cleveland Clinic Children's Hospital, Cleveland, Ohio, United States
  • Reidy, Kimberly J., Children's Hospital at Montefiore, Bronx, New York, United States

Group or Team Name

  • Pediatric Working Group of the NEPTUNE study
Background

Hyperfiltration has been reported in nephrotic syndrome. Pediatric GFR estimating equations were developed with data primarily on children with decreased GFRs, and the accuracy of these formulas with elevated GFRs is unknown. Because hyperfiltration may be deleterious, inaccurate estimated GFRs (eGFRs) in this patient population may generate false clinical reassurance. The objectives of this study in the pediatric NEPTUNE cohort were: (1) to examine whether the variance between two pediatric eGFR estimating formulas differs by hyperfiltration status; and (2) to compare the prevalence of hyperfiltration while in first remission in this cohort.

Methods

eGFR was calculated using the creatinine based pediatric "bedside" Schwartz formula and the CKID U25 formula. Hyperfiltration was defined as eGFR ≥140 ml/min/1.73m2. First remission was defined as the first urine protein:creatinine (UPC) <0.3 mg/mg for which there was an available serum creatinine obtained at the same time. For Aim 1, all available serum creatinines obtained on patients 1- <18 years of age were utilized irrespective of proteinuria status. Absolute differences between the two eGFR formulas were calculated and the difference in those with and without hyperfiltration were compared by t-test (two-sample unequal variance). For Aim 2, only the subset of pediatric patients who achieved first remission were included.

Results

A total of 3570 serum creatinine values from 320 unique patient with a median age of 6 years (35% minimal change disease, MCD, 20% focal segmental glomerulosclerosis, FSGS, 45% not biopsied) were available for analysis. The median [interquartile range] difference between the eGFRs using the two estimating formulas in patients with vs without hyperfiltration was 23 [16.9-28] vs. 11 [6.8-15.2] mL/min/1.73m2, respectively (p <0.001). For children who achieved first remission (n=233), 12.5% had hyperfiltration by “bedside” Schwartz vs. 7.7% by the U25 formula.

Conclusion

Pediatric NEPTUNE patients with hyperfiltration vs. not demonstrate higher variability in eGFRs using two common pediatric estimating equations, and rates of hyperfiltration (in remission) also vary based on the formula used. These data suggest estimating equations may be less accurate in children with nephrotic syndrome and indicate more research is needed to better refine eGFR estimation formulas for this population.

Funding

  • NIDDK Support