A comparison of the plasma disappearance of iohexol and 99mTc-DTPA for the measurement of glomerular filtration rate (GFR) in diabetes

Aust N Z J Med. 1999 Oct;29(5):693-700. doi: 10.1111/j.1445-5994.1999.tb01617.x.


Background: Changes in glomerular filtration rate (GFR) provide a valuable indicator of the progression of diabetic nephropathy. GFR is most commonly measured by the plasma clearance of radioisotopes, however, use of iohexol, a non-ionic radiocontrast medium, is a recently described alternative and has shown good agreement with inulin clearance. A one-compartment model is used for calculating GFR in most Australian centres but a two-compartment model is more accurate.

Aims: To set up a non-radioisotopic method for assessment of GFR using iohexol, and to compare this with the currently used 99mTc-diethylene-triamine-penta-acetic acid (DTPA) method. Secondly, to compare GFR results using an unmodified one-compartment model with a one-compartment model subjected to the Brochner-Mortensen modification.

Methods: Twenty-one patients with diabetes had assessment of GFR with simultaneous measurements of 99mTc-DTPA and iohexol plasma clearance. Plasma clearance was determined by the slope intercept method and then modified according to the Brochner-Mortensen equation. Plasma iohexol concentrations were determined by capillary electrophoresis.

Results: There was no significant difference between iohexol and 99mTc-DTPA derived GFR values, difference 4.3+/-7.7 mL/minute (mean+/-SD). This was despite 99mTc-DTPA protein binding demonstrated in the range of 5-10%. Comparison of GFR results using an unmodified one-compartment model with a Brochner-Mortensen corrected one-compartment model showed higher GFR values with the former, in the range of 20-30% for GFR values > 100 mL/minute.

Conclusion: Iohexol provides an efficient alternative to radioisotopic methods for serial measurement of GFR in diabetic patients with hyperfiltration, incipient and overt nephropathy. A one-compartment model with its inherent overestimation of GFR should be replaced by the Brochner-Mortensen modified one-compartment model.

Publication types

  • Clinical Trial
  • Comparative Study

MeSH terms

  • Adult
  • Aged
  • Contrast Media*
  • Diabetes Mellitus / blood
  • Diabetes Mellitus / physiopathology*
  • Electrophoresis, Capillary
  • Female
  • Glomerular Filtration Rate*
  • Humans
  • Iohexol*
  • Male
  • Metabolic Clearance Rate
  • Middle Aged
  • Technetium Tc 99m Pentetate* / blood


  • Contrast Media
  • Iohexol
  • Technetium Tc 99m Pentetate