Errrrr, Dutch, don't you mean if the eGFR is
BELOW 60, no contrast is given???
And, if it's
ABOVE 60 (meaning the kidneys are functioning well, i.e., have a higher filtration rate) then contrast may be given?
I've never heard of any formula, based on the eGFR, by which one determines the amount of contrast to be given.
I just did an online search (not exhaustive

) and found no formulas.
I did find the following useful links to articles dealing with CIN prevention and treatment:
http://www.medicalimagingmag.com/iss...007-05_CIN.asp
http://ndt.oxfordjournals.org/cgi/co...full/22/7/1812
http://www.imagingeconomics.com/issu...2007-05_11.asp
In general, the Cardiologists and Radiologists I've worked with go by the pt's weight: goal is to give ml of contrast below the wt (in lb, e.g.: goal is no more than 150ml of contrast for a 150# person, or, 2X the wt in kg: no more than 150ml contrast for a 75kg person).
There are times when the benefit of giving more outweighs the risk of CIN. This is a clinical decision, to be made by the MDs.
papaRTRCT, I'd be interested to see the formula the nurses of which you speak are using, and where they obtained it (evidence-based!), for my own edification.
BTW, kudos to you for searching out evidence-based guidelines/practices.
Have worked with many excellent techs through the years, worth their weight in gold! It's a team thing!