Chronic renal failure (CRF) is present when there is a persistent, irreversible decrease in the glomerular filtration rate (GFR). Chronic renal insufficiency (CRI) has been defined as a GFR of 50-75 ml/min/1. 73 m2, and CRF is present when the GFR is 10-50 ml/min/1. 73 m2. Accurate determination of renal function is crucial for the diagnosis and monitoring of CRF. Availability, expense and technical issues limit the use of inulin, the gold standard for determination of GFR, to specialized centers and research protocols. Regardless of the primary cause of CRF, the final renal histologic findings are similar, suggesting a common pathway toward ESKD. It is believed that glomerular and tubular adaptive alterations to the initial insult, such as hyperperfusion and glomerular hypertension, occur in the remaining nephrons and ultimately contribute to the global deterioration of kidney function.