This data repository contains two csv files with the data that were used for the analyses. One dataset contains the data of the Utrecht cohort, containing rat identification numbers, strain, weight, serum creatinine, serum urea, mGFR measured with sinistrin clearance and eGFR. The other dataset contains the data of the Rotterdam cohort, containing rat identification numbers, whether the rat was a control subject or not, the weight, serum creatinine, serum urea, tGFR calculated with the one compartment assumption, days between the tGFR measurement and the serum creatinine/urea measurement, Quality of the curve, and tGFR calculated with the three compartment model. Furthermore we added csv files of all the raw data produced by the transcutaneous measurements in the Rotterdam cohort.