Clinical features of C.R.F begin to appear when renal function is reduced to:

Stage 1 and 2 of CKD are asymptomatic Symptoms beginning in Stage 3. Stage 3 begins at GFR of < 60ml/ min/ 1.73m2 body surface area. Clinical features of CRF will develop when >50% or more of kidney parenchyma is destroyed. Renal injury , kidney has innate ability to maintain GFR-remaining healthy nephrons manifest hyperfiltration and compensatory hyperophy. This nephron adaptability allows for continued normal clearance of plasma solutes. The Plasma levels of substances such as urea and creatinine sta to show measurable increases only after total GFR has decreased to 50%.