Only about 1% of the glomerular filtrate becomes urine. This is one of the many facets of Renal Physiology. The nephrons are the part of the kidneys which are responsible for filtering the blood. Along with the blood are cells, proteins, and large molecules that also filtered by the nephrons through the process of ultrafiltration. Only a few of these deposits are turned into urine when they reach the collecting ducts of the kidneys.
