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Abstract: SA-PO393

Revisiting Clinical Relevance of Radionucleotide-Based GFR Estimation and Comparison with CKiD U25 eGFR Equation in Pediatric Liver Transplant Patients

Session Information

  • Pediatric Nephrology - III
    November 04, 2023 | Location: Exhibit Hall, Pennsylvania Convention Center
    Abstract Time: 10:00 AM - 12:00 PM

Category: Pediatric Nephrology

  • 1900 Pediatric Nephrology

Authors

  • Chadha, Vimal, Children's Mercy Kansas City, Kansas City, Missouri, United States
  • Cully, Brent, Children's Mercy Kansas City, Kansas City, Missouri, United States
  • Slowik, Voytek, Children's Mercy Kansas City, Kansas City, Missouri, United States
Background

Renal dysfunction is common in patients with liver transplant recipients and can be present at the time of transplant or develop later during follow-up. Kidney function in these patients is monitored periodically by measuring glomerular filtration rate (GFR). In the absence of appropriate serum creatinine-based estimation equations in the past, GFR measurement by utilizing radionucleotide agent such as diethylenetriamine pentaacetate (DTPA) have been in common practice. The procedure involves IV line placements, radionucleotide agent administration, and blood draws. The value of newer GFR estimating equations such as CKiD U25 (derived form Chronic Kidney Disease in Children Under 25) have not been evaluated in these cases.

Methods

Retrospective analysis of all liver transplant patients since 1995 who had their GFR estimated by radionucleotide (99mTc-DTPA) for kidney function monitoring. The DTPA-GFR was compared with eGFR calculated by creatinine based CKiD U25 equation. All creatinine values were converted to isotope dilution mass spectrometry (IDMS) reference measurement. Patients with any missing data were excluded.

Results

356 DTPA-GFR measurements (median 4 per patient; range 1 – 9) from 95 patients (57% males; median age at transplant 2.1 years, range 0.45 – 19.2) obtained at a median age of 10 years were available. 53 (15%) serum creatinine values were above the age specific reference range and the eGFR by U25 equation was <90 mL/min for all, while 40 had <90 mL/min, 11 had between 90 – 120, and 2 had >120 mL/min based on DTPA-GFR. 303 serum creatinine values were in normal range and the GFR was >120 mL/min in 94 (31%) by both methods. Of the rest of 209 values, U25 equation classified 147 (90 – 120 mL/min) and 18 (<90 mL/min); while DTPA-GFR classified 115 (90 – 120 mL/min) and 28 (<90 mL/min). The concordance between U25 and DTPA-GFR was ~50% for eGFR 90 – 120 mL/min, and ~15% for <90 mL/min, respectively. Overall, the correlation coefficient “r” between the two methods was 0.45 (p <0.0001).

Conclusion

In the absence of the gold-standard measurement, CKiD U25 equation appears to perform better than DTPA-GFR which is a time consuming, cumbersome and expensive procedure. Addition of serum Cystatin C is likely to further improve the eGFR estimation by CKiD U25 equation.