Classification of the stages of chronic kidney disease, as follows:
Stage 1: Kidney damage with normal or increased GFR (more than 90 mL/min/1.73 m2)Stage 2: Mild reduction in GFR (60-89 mL/min/1.73 m2)Stage 3: Moderate reduction in GFR (30-59 mL/min/1.73 m2)Stage 4: Severe reduction in GFR (15-29 mL/min/1.73 m2)Stage 5: Kidney failure (GFR less than15 mL/min/1.73 m2 or dialysis)
Approximately 1 million nephrons are present in each kidney, each contributing to the total GFR.Urea and creatinine start to show significant increases in plasma levels only after total GFR has decreased to 50%, when the renal reserve has been exhausted.The plasma creatinine value will approximately double with a 50% reduction in GFR.
The goal of therapy is to slow down or halt the otherwise relentless progression of CKD to stage 5.Generally, angiotensin converting enzyme inhibitors (ACEIs) or angiotensin II receptor antagonists are used, as they have been found to slow the progression of CKD to stage 5.Replacement of erythropoietin and calcitriol, two hormones processed by the kidney, is often necessary in patients with advanced CKD. Phosphate binders are also used to control the serum phosphate levels, which are usually elevated in advanced chronic kidney disease.When one reaches stage 5 CKD, renal replacement therapy is required, in the form of either dialysis or a transplant.