Chronic kidney disease staging is crucial for figuring out the risk of disease progression and to guide management. In this video, from our Kidney Test Essentials course, you'll learn how to accurately stage your chronic kidney disease patients and how this will affect the way you manage them.
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Taking a shotgun approach to kidney function testing can be tempting if nephrology is not your forte. By the end of this course, however, you’ll be comfortable ordering and interpreting all common kidney function tests. You’ll understand the clinical implications of abnormalities seen on these tests and will be able to form a practical plan of action.
The kidney disease outcomes quality initiative from the National Kidney Foundation has developed guidelines for the detection and evaluation of chronic kidney disease. If creatinine clearance is above 90 ml per minute per 1.73 meters squared, or preferably above 100, in the absence of any abnormal finding, either on imaging study or laboratory based test, normal kidney function can be assumed.
If kidney damage defined as structural damage of the kidney, based on imaging studies, or functional damage based on laboratory test is present for three months or more than it is usually assumed that chronic kidney disease is present. And if GFR is below 60 ml per minute for three or more months, it can also be assumed that the patient has chronic kidney disease.
End-stage renal disease or end-stage renal failure is present if the GFR is below 15 ml per minute, or if the patient requires dialysis. The purpose of chronic kidney disease staging is to guide management, including stratification of risk of disease progression and risk of complications. Risk stratification is used to decide on appropriate treatments and determine the intensity of monitoring.
The glomerular filtration rate, G stages, follow the chronic kidney disease classification scheme. G1 is a GFR greater than 90 ml per minute per 1.73 meters squared. G2 is a GFR 60 to 89 ml per minute, or 1.73 meters squared. G3 is a GFR 30 to 59 ml per minute per 1.73 meter squared. G4 is a GFR 15 to 29 ml per minute per 1.73 meters squared. G5 is when the GFR is less than 15 ml per minute per 1.73 meter squared, or there is treatment by dialysis.
Stage three chronic kidney disease has been subdivided into GFR stages 3A and 3B to more accurately reflect the association between the lower GFR of stage 3B and the risk of death and adverse kidney outcomes. Patients receiving treatment with dialysis are subclassified as GFR stage 5D to highlight the specialized care that they require.
Chronic kidney disease can also be staged using the level of albuminuria. The three albuminuria stages use definitions of normal, moderately increased and severely increased albuminuria. A1, or normal is an albumin to creatinine ratio less than 30 milligrams per gram, which is equivalent to less than 3.4 milligrams per millimole. A2, or microalbuminuria is an albumin to creatinine ratio between 30 to 299 milligrams per gram, which is equivalent to 3.4 to 34 milligrams per millimoles.
A3, or macroalbuminuria is an albumin to creatinine ratio equal to or greater than 300 milligrams per gram, which is equivalent to greater than 34 milligrams per millimole. Get familiar with these guidelines for accurately staging your chronic kidney disease patients as they will ultimately help guide your decisions regarding the patient's treatment.