The Gates-based renography (gGFR) and plasma-based clearance rate (pGFR) are conventionally corrected with body surface area (BSA). Limited studies indicated that the lean body mass (LBM) might be better than BSA in correcting pGFR. Therefore, we suggest that LBM is also better in correcting gGFR and improve the correlation coefficient between gGFR and pGFR.
During June 2009 and December 2010, the gGFR and pGFR of 63 patients with hydronephrosis were measured and corrected with BSA and LBM, respectively. The correlation and regression analyses were conducted to illustrate the power of BSA and LBM correction.
In a paired t test, there was no significant difference between pGFR and gGFR in patients with stages 1 and 2, although this was significant in stages 3 and 4. However, neither LBM nor BSA correction could eliminate the difference. In all patients (N = 63), the correlation coefficient (r) between pGFR and gGFR was 0.794 (P <; 0.001). After the BSA and LBM correction, r was improved to 0.809 and 0.828, respectively. In all patients, the regression line of pGFRLBM − gGFRLBM was nearer to the original point and its slope closer to 1 than pGFRBSA − gGFRBSA and pGFR − gGFR. Similar results were found in the analysis of most stages and subgroups.
The commonsense of BSA correction should be seriously reevaluated. Lean body mass can better improve the correlation coefficient between paired GFRs than BSA can and it can be suitable in the correction.
From the *Department of Nuclear Medicine, the First Affiliated Hospital of Shanxi Medical University, Taiyuan, Shanxi Province; and †Department of Nuclear Medicine, Cancer Hospital, Peking Union Medical College, Beijing, China.
Received for publication December 16, 2011; revision accepted May 15, 2012.
Dr Si is currently with the Department of Nuclear Medicine, the First Affiliated Hospital of Anhui Medical University, Hefei, Anhui Province, China.
Conflicts of interest and sources of funding: The work received a grant (no. 090413132) from Natural Science Foundation of Anhui Province of China. For the remaining authors, none were declared.
Correspondence to: Sijin Li, MD, Department of Nuclear Medicine, the First Affiliated Hospital of Shanxi Medical University, Taiyuan, Shanxi Province, 030001, China. E-mail: Sihw@163.com.