Glomerular Filtration Rate Calculation Spreadsheet

This program is designed to calculate GFR measurements from blood samples taken from patient after administration of a low dose (~20 uCi) of I-125, Tc-99m, Cr-51

In this sheet, full curve characterization of plasma activity curves is calculated using biexponential modelling. In addition, GFR calculations are derived using single compartment methods and single time point methods, for comparison.

INSTRUCTIONS: To use the worksheet, ensure all grey cells are completed – GFR calculations should auto update. Sheet requires 4-10 sample points (at least two to fit early curve, and two to fit late curve).

Our GFR worksheet is modelled after the protocols and calculations described in:

Assessment of glomerular filtration rate measurement with plasma sampling: a technical review, Murray AW, Barnfield MC, Waller ML, Telford T, Peters AM, JNMT, 2013

To obtain a copy of the DenverGFR V2.01e worksheet, please send request to

DISCLAIMER: This worksheet has not been extensively tested or validated and is provided on this site as a resource tool only. GFR calculations and treatment decisions remain the responsibility of the treating physician. The user of this tool holds free from any and all liability the Regents of the University of Colorado, a body corporate, and all associated parties.


Version 1.0 – [Feb 2014] : initial release

Version 1.01 – [Sept 2014] : added capacity to handle non-conforming data point (not likely, but possible to occur)

Version 1.02 – [Feb 2014] : added selection of isotope for user (I-125, Tc-99m, Cr-51)

Version 2.0 – [March 2016] : (A) adjusted early/late cutoff, used for curve fitting. It used to be hardcoded at 120 minutes, but is now defined by the median time point (research showed this provides more stable calculations, less dependent on the specific combination of late time points used. We aim to publish this work in 2016/2017). (B) Added error catching features – negative early curves not included in calculations and won’t crash sheet (these should not occur with realistic data). (C) Fixed errors with metric units on metric sheet.

Version 2.01 [April 2016] : (B) standard no longer requires 1000 cc dilution, user can use any volume. (B) allows access to early-late cutoff time cell on the calculations page (relevant for the curve fitting).

Please address any questions, or requests for an editable worksheet, to Adam Kesner: We would love to hear if you found this resource useful!