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Kidney Week

Abstract: SA-PO991

Assessing Kidney Function in Combined Heart-Kidney Transplant Candidates: Challenges and Opportunities

Session Information

Category: Transplantation

  • 2102 Transplantation: Clinical

Authors

  • Agarwal, Krishna A., Tufts Medical Center, Boston, Massachusetts, United States
  • Srivastava, Aman, Tufts Medical Center, Boston, Massachusetts, United States
  • Levey, Andrew S., Tufts Medical Center, Boston, Massachusetts, United States
  • Inker, Lesley Ann, Tufts Medical Center, Boston, Massachusetts, United States
Background

Heart transplant candidates often have concomitant kidney disease, necessitating simultaneous heart-kidney transplantation (SHKT). UNOS outlined GFR cutoffs for allocating heart-kidneys in 2023. A heart transplant (HT) candidate with baseline CKD can qualify for SHKT with GFR<=30 or with sustained AKI if GFR<=25. Unfortunately, there is no guidance for appropriate methods of assessing GFR in these patients with heart failure who can be volume expanded and sarcopenic and hence have inaccurate creatinine based GFR (eGFRcr). While cystatin based GFR (eGFRcys) is an alternative, it is known to have high error rates as well.

Methods

We present 5 cases of HT candidates who were evaluated for SHKT. Only one of them (#2) had peripheral edema on exam. As part of pre-transplant evaluation, eGFRcr, eGFRcys, eGFRcr-cys (CKD-EPI 2021), 24-hour urinary creatinine clearance (mClcr) and measured GFR using plasma iohexol clearance (mGFR) were obtained. For mGFR, blood samples were drawn at 2, 4, 6 and 24 hours after iohexol injection and GFR was determined using a two-compartment model with the Brochner-Mortenson correction.

Results

There was wide discrepancy between eGFRcr and mGFR, with eGFRcr overestimating mGFR for all five patients (Table 1). eGFRcys and eGFRcr-cys were more similar to mGFR. Urine mClcr did not corelate with mGFR.

Conclusion

In HT candidates being evaluated for SHKT, it is essential to have an accurate assessment of GFR. eGFRcr alone is fraught with inaccuracies. Our findings support the use of guideline-recommended eGFRcr-cys (CKD-EPI 2021) with comprehensive evaluation using cystatin C and mGFR. Transplant centers should consider collaborating with laboratory scientists to implement measurement protocols for cystatin C and mGFR for assessing dual organ transplant eligibility.

IDCreatinine (mg/dL)eGFRcr (mL/min/1.73m2)Cystatin C (mg/L)eGFRcys (mL/min/1.73m2)eGFRcr-cys (mL/min/1.73m2)mClcr (mL/min/1.73m2)mGFR (mL/min/1.73m2)
11.25542.0829384542
22.98243.551518UNK17
31.70342.5021263221
41.26491.7136412635
52.27381.9635362337