New data are suggesting functional adaptive hyperfiltration may be more important than structural adaptive hypertrophy for the recovery of renal function following radical nephrectomy (RN).

Researchers at the Samsung Medical Center, Sungkyunkwan University School of Medicine in Korea have found that patients with renal cell carcinoma (RCC) who have lower preoperative GFR had less of a reduction in postoperative renal function than patients with higher preoperative GFR due to greater degrees of functional hyperfiltration.1

Choi and colleagues investigated structural hypertrophy and functional hyperfiltration as compensatory adaptations following RN in 543 patients with RCC.

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All the patients were retrospectively identified and underwent RN between 1997 and 2012. Patients were classified according to preoperative GFR and CKD stage. The researchers assessed functional renal volume (FRV) through CT images taken within 2 months prior to surgery and 12 months after surgery.

The mean age of the patients was 56.0 years and the mean preoperative GFR was 83.2 mL/min/1.73m2. The mean preoperative FRV was 340.6 cm3 and the mean preoperative GFR/FRV was 0.25 ml/min/1.73m2/cm3.

The researchers found the reduction in GFR was statistically significant according to CKD stage (no CKD -31.2% compared to CKD stage 2 -26.5%). The reduction in GFR for CKD stage 3 was -12.8%.

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While the degree of hypertrophic FRV in the remnant kidney was not statistically significant, the change in GFR/FRV was statistically significant (no CKD was 18.5% compared to 20.1% for CKD stage 2).

The change in GFR/FRV was 45.9% in the CKD stage 3. The researchers write that factors that increased GFR/FRV above the mean value were body mass index, diabetes mellitus, hypertension, and CKD stage.