The eGFR values (only ranges but not absolute) are calculated according to a formula for eGFR Cockroft-Gault, Mayo Quadratic using CKD-EPI and using MDRD,6 Variable (mentioned below) This formula estimates the target levels of
GFR in CKD subjects (Chronic Kidney Disease),while your values of Creatinine-1.3 mg/dl
and GFR-47 fall under category of CKD Stage-III.
GFR can be calculated using various formulas and various tests to estimate the range of Kidney Function.