title: Comparison of glomerular filtration rate measured by plasma sample technique, Cockroft Gault method and Gates' method in voluntary kidney donors and renal transplant recipients.
abstract: BACKGROUND
  There are numerous methods for calculation of glomerular filtration rate (GFR), which is a crucial measurement to identify patients with renal disease.
  
  
  OBJECTIVE
  The aim of this study is to compare four different methods of GFR calculation.
  
  
  METHODS
  Clinical setup, prospective study.
  
  
  METHODS
  Data was collected from routine renal scans done for voluntary kidney donors (VKD) or renal transplant recipients 6 months after transplantation. Following technetium-99m diethylene triamine penta acetic acid injection, venous blood samples were collected from contralateral arm at 120, 180, and 240 min through an indwelling venous cannula and direct collection by syringe. A total volume of 1 ml of plasma from each sample and standards were counted in an automatic gamma counter for 1 min. Blood samples taken at 120 min and 240 min were used for double plasma sample method (DPSM) and a sample taken at 180 min for single plasma sample method (SPSM). Russell's formulae for SPSM and DPSM were used for GFR estimation. Gates' method GFR was calculated by vendor provided software. Correlation analysis was performed using Pearson's correlation test.
  
  
  RESULTS
  SPSM correlated well with DPSM. GFR value in healthy potential kidney donors has a significant role in the selection of donors. The mean GFR ± (standard deviation) in VKD using SPSM, DPSM, camera depth method and Cockroft Gault method was 134.6 (25.9), 137.5 (42.4), 98.6 (15.9), 83.5 (21.1) respectively. Gates' GFR calculation did not correlate well with plasma sampling method.
  
  
  CONCLUSIONS
  Calculation of GFR plays a vital role in the management of renal patients, hence it was noted that Gates GFR may not be a reliable method of calculation. SPSM was more reliable. DPSM is reliable but cumbersome. It is difficult to accurately calculate GFR without a gold standard.
authors.affiliation: Department of Nuclear Medicine, Christian Medical College, Vellore, Tamil Nadu, India.
authors.forename: Julie
authors.initials: J
authors.lastname: Hephzibah
authors.forename: Nylla
authors.initials: N
authors.lastname: Shanthly
authors.forename: Regi
authors.initials: R
authors.lastname: Oommen
keywords: Cockroft Gault method; Gates method; double plasma sample method; glomerular filtration rate; post-renal transplant recipients; single plasma sampling method; voluntary kidney donors