Chronic renal failure (CRF) is the progressive loss of kidney function over time. It can be caused by conditions that damage the nephrons like diabetes and hypertension. As kidney function declines, waste products build up in the bloodstream. CRF is classified by the location of damage as pre-renal, post-renal, or renal. The most common causes of renal CRF are diabetes and high blood pressure. Multiple myeloma can also lead to CRF through protein deposits and other complications.