Estimated GFR by Serum Myo-inositol, Valine, Creatinine, and Cystatin-c Outperforms Current CKD-epi Equations in Renal Transplant Recipients
1Cardiovascular Laboratory Medicine, Mayo Clinic, Rochester, MA, 2Research and Development, Numares, Boston, MA, 3Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN, 4Clinical Research, Numares, Boston, MA
Meeting: 2021 American Transplant Congress
Abstract number: LB 31
Keywords: Glomerular filtration rate (GFR), Kidney, Kidney transplantation, NMR spectroscopy
Topic: Clinical Science » Biomarkers, Immune Assessment and Clinical Outcomes
Session Information
Session Name: Biomarkers, Immune Assessment and Clinical Outcomes
Session Type: Poster Abstract
Session Date & Time: None. Available on demand.
Location: Virtual
*Purpose: Current estimated GFR (eGFR) equations using creatinine and/or cystatin C do no perform well in kidney transplant (KTx) recipients. Therefore, some large transplant programs instead measure GFR as part of their routine pre and post-transplant protocols. However, these methods are expensive and not readily available in many areas. Recently, we developed a novel GFR equation, which utilizes serum myo-inositol, valine and creatinine quantified by nuclear magnetic resonance spectroscopy (NMR) in combination with Cystatin-C measured by immunoturbidometric assay, age and sex (GFRNMR). In the current study we evaluated performance of this equation in a cohort of KTx recipients.
*Methods: GFR was measured (mGFR) by renal Iothalamate clearance in 109 post KTx patients that scheduled visits as part of routine clinical care (573 days; range 2-5217 days). mGFR was compared to eGFRNMR , as well as the CKD EPI equations using creatinine (eGFRCr), Cystatin C (eGFRCyC), or both (eGFRCr CyC).
*Results: CKD-EPIcys was the least accurate with a P30 value of 0.73 and a MAE of 10.7 ml/min/1.73m². CKD-EPIcr, was better with a P30 of 0.81 and a MAE of 9.53 ml/min/1.73m². The CKD-EPIcr-cys, which has been established to lessen the effects of age, sex and race to improve GFR estimation, had a P30 value of 0.87 and a MAE of 9.41 ml/min/1.73m². Subgroup analysis of individuals with GFR < 60ml/min/1.73m² showed that this formula significantly underestimates renal reserve in renal transplant recipients. In contrast, GFRNMR across the entire range of GFR showed good accuracy to measured GFR with a P30 of 0.92 and a MAE of 7.45 ml/min/1.73m². Further subgroup analysis of individuals with a GFR < 60 ml/min/1.73m² showed minimal bias with mGFR.
*Conclusions: Our study demonstrates the potential utility of a novel eGFRNMR method for assessing kidney function in post KTx patients. This equation has improved performance compared to the established and widely utilize CKDEPI equations. Thus, eGFRNMR has great potential as a cost effective and non-invasive alternative to mGFR that could be widely available as a referral laboratory test. Further studies are necessary to validate this novel equation in additional post Tx and other CKD and non CKD cohort.
| mean GFR (SD) | MAE (95%CI) | P30 (95%CI) | RMSE(95%CI) | |
| mGFR | 55.83 (20.28) | Ref | Ref | Ref |
| eGFRNMR | 55.74 (19.12) | 7.45 [6.3-8.47] | 91.74 [87.16-97.25] | 9.42 [8.31 -10.58] |
| eGFRcr | 51.75 (19.83) | 9.53 [8.11 -10.93] | 80.73 (74.31-88.07)
|
12.23 (10.65-13.93) |
| eGFRCyC | 48.14 (20.98) | 10.74 (9.26-12.26) | 72.48 (64.22-80.73) | 13.61 (12.01-15.39) |
| eGFRCRCyC | 48.99 (19.87) | 9.41 (8.09-10.75) | 87.16 (80.73-93.55) | 11.78(10.39-13.22) |
To cite this abstract in AMA style:
Meeusen JW, Stammler F, Lieske J, Grassi M, Shah M, Schiffer E. Estimated GFR by Serum Myo-inositol, Valine, Creatinine, and Cystatin-c Outperforms Current CKD-epi Equations in Renal Transplant Recipients [abstract]. Am J Transplant. 2021; 21 (suppl 3). https://atcmeetingabstracts.com/abstract/estimated-gfr-by-serum-myo-inositol-valine-creatinine-and-cystatin-c-outperforms-current-ckd-epi-equations-in-renal-transplant-recipients/. Accessed May 11, 2025.« Back to 2021 American Transplant Congress