title: Lean body mass is better than body surface area in correcting GFR.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
  
  
  RESULTS
  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 pGFR(LBM) - gGFR(LBM) was nearer to the original point and its slope closer to 1 than pGFR(BSA) - gGFR(BSA) and pGFR - gGFR. Similar results were found in the analysis of most stages and subgroups.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Nuclear Medicine, the First Affiliated Hospital of Shanxi Medical University, Taiyuan, Shanxi Province, China.
authors.forename: Hongwei
authors.initials: H
authors.lastname: Si
authors.forename: Zhili
authors.initials: Z
authors.lastname: Lei
authors.forename: Sijin
authors.initials: S
authors.lastname: Li
authors.forename: Jianzhong
authors.initials: J
authors.lastname: Liu
authors.forename: Jianhua
authors.initials: J
authors.lastname: Geng
authors.forename: Shengzu
authors.initials: S
authors.lastname: Chen
mesh_terms: D000328:Adult; D001830:Body Surface Area; D001835:Body Weight; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006869:Hydronephrosis / Q000097:blood / Q000000981:diagnostic imaging / Q000503:physiopathology; D007677:Kidney Function Tests / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011866:Radioisotope Renography; D012044:Regression Analysis