Measurement of renal function in a kidney donor: a comparison of creatinine-based and volume-based GFRs.

OBJECTIVE

We aimed to evaluate the performance of various GFR estimates compared with direct measurement of GFR (dGFR). We also sought to create a new formula for volume-based GFR (new-vGFR) using kidney volume determined by CT.

MATERIALS AND METHODS

GFR was measured using creatinine-based methods (MDRD, the Cockcroft-Gault equation, CKD-EPI formula, and the Mayo clinic formula) and the Herts method, which is volume-based (vGFR). We compared performance between GFR estimates and created a new vGFR model by multiple linear regression analysis.

RESULTS

Among the creatinine-based GFR estimates, the MDRD and C-G equations were similarly associated with dGFR (correlation and concordance coefficients of 0.359 and 0.369 and 0.354 and 0.318, respectively). We developed the following new kidney volume-based GFR formula: 217.48-0.39XA + 0.25XW-0.46XH-54.01XsCr + 0.02XV-19.89 (if female) (A = age, W = weight, H = height, sCr = serum creatinine level, V = total kidney volume). The MDRD and CKD-EPI had relatively better accuracy than the other creatinine-based methods (30.7% vs. 32.3% within 10% and 78.0% vs. 73.0% within 30%, respectively). However, the new-vGFR formula had the most accurate results among all of the analyzed methods (37.4% within 10% and 84.6% within 30%).

CONCLUSIONS

The new-vGFR can replace dGFR or creatinine-based GFR for assessing kidney function in donors and healthy individuals.

KEY POINTS

• Accurate prediction of GFR is crucial in kidney donors. • DTPA is accurate but costly, invasive, and clinically difficult to apply. • Volume-based GFR estimation performs as well as the Cr-based method. • New volume-based GFR estimation performs better among GFR estimation formulas.