The development of chronic renal failure is insidious initially causing no symptoms. As the function of the Kidneys decline over time, non-specific symptoms develop. It is not until advanced irreversable renal failure is reached are appreciable signs such as difficult to treat high blood pressure and swelling develop. 

A key assessment of renal function is the estimation of the glomerular filtration rate (eGFR) which is a measure of how well kidneys are filtering blood.   Chronic Kidney disease is defined by a low eGFR <60 mL/min/1.73 m²  that is persistent over three or more months.  Calculating eGFR requires measurement of creatinine in the blood.