title: Determination of glomerular filtration rate using technetium-99m-DTPA with differing degrees of renal function.
abstract: Glomerular filtration rate (GFR) is an important index of renal function. Twenty-four-hour creatinine clearance overestimates GFR in patients with poor renal function. Inulin and iothalamate clearances are accepted reference standards for determining GFR but are expensive and laborious. We have previously reported that GFRs obtained by measuring the disappearance of 99mTc-DTPA from ultrafiltered (protein-free) samples of plasma were virtually identical to those obtained by the iothalamate method. However, the subjects used in that study had normal to only moderately decreased renal function.
  
  
  METHODS
  The accuracy of measuring GFR by plasma clearance of 99mTc-DTPA was determined in subjects where renal function varied from normal to severely impaired. In all subjects, GFR was established by clearance of 125I-iothalamate from urine and serum and was used as the standard of reference.
  
  
  RESULTS
  For subjects with normal to moderately diminished renal function (GFR > 20 ml/min), the correlation between values of GFR obtained by the DTPA and iothalamate methods was high (n = 18, r = 0.966). The difference between the pairs of GFR values obtained by the two methods was not statistically significant (p > 0.1). In patients with severe renal insufficiency (GFR < 20 ml/min), the correlation between the DTPA and iothalamate methods was poor (n = 11, r = 0.236), and the GFR values obtained by the two methods were statistically different (p < 0.01).
  
  
  CONCLUSIONS
  These results suggest that GFR can be determined accurately by plasma clearance of 99mTc-DTPA in all patients except those with severe renal insufficiency.
authors.affiliation: Imaging Service, VA Medical Center, Portland, Oregon 97207, USA.
authors.forename: K A
authors.initials: KA
authors.lastname: Morton
authors.forename: D E
authors.initials: DE
authors.lastname: Pisani
authors.forename: J H
authors.initials: JH
authors.lastname: Whiting
authors.forename: A K
authors.initials: AK
authors.lastname: Cheung
authors.forename: J M
authors.initials: JM
authors.lastname: Arias
authors.forename: S
authors.initials: S
authors.lastname: Valdivia
mesh_terms: D000328:Adult; D003287:Contrast Media; D003404:Creatinine / Q000652:urine; D005260:Female; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007444:Inulin; D007457:Iodine Radioisotopes / Q000097:blood / Q000652:urine; D007483:Iothalamic Acid / Q000493:pharmacokinetics; D007676:Kidney Failure, Chronic / Q000000981:diagnostic imaging / Q000503:physiopathology; D008297:Male; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals / Q000097:blood / Q000652:urine; D051437:Renal Insufficiency / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012680:Sensitivity and Specificity; D016284:Technetium Tc 99m Pentetate / Q000097:blood; D014462:Ultrafiltration
chemical_list: D003287:Contrast Media; D007457:Iodine Radioisotopes; D019275:Radiopharmaceuticals; D007483:Iothalamic Acid; D007444:Inulin; D003404:Creatinine; D016284:Technetium Tc 99m Pentetate