How are the stages of chronic kidney disease defined?
What are the different dialysis modalities, and how do patients choose one over another?
What is the difference between an arteriovenous fistula and an arteriovenous graft? What are their associated complications?
When is it appropriate to initiate dialysis?
How are hemodialysis and peritoneal dialysis performed? What are their common complications?
What complications are common in hospitalized patients with chronic kidney disease?
Over 26 million Americans, or approximately one in nine adults, have chronic kidney disease (CKD). These patients require special attention from hospitalists because of a high incidence of acute kidney injury (AKI) and other complications during hospitalization. These patients are at risk of AKI not only from known nephrotoxins, such as contrast agents and nonsteroidal anti-inflammatory drugs (NSAIDs), but also from other commonly prescribed agents. Other major issues in the hospital care of these patients include preservation of venous access, electrolyte and acid-base correction, and anemia management. As many of these patients advance to end-stage renal disease (ESRD) requiring dialysis, hospitalists should have a basic understanding of the principles of renal replacement therapy (RRT).
The National Kidney Foundation has defined a staging system for CKD (Table 248-1) based on glomerular filtration rate (GFR) as the best marker of kidney function. CKD is defined as an absolute GFR less than 60 cc/min, or structural or functional kidney abnormalities eg, hematuria, proteinuria, abnormal imaging) with a preserved GFR (> 90cc/min). Serum creatinine concentration (sCr) is a poor marker of kidney function, as normal values vary with age, gender, and muscle mass. It is especially inadequate in the setting of AKI. In the early stages of serious kidney injury, the sCr may be falsely reassuring, as it may only rise well after the initial insult. GFR is a better marker of kidney function and is used as the basis for the staging system.
Table 248-1 Chronic Kidney Disease Staging System ||Download (.pdf)
Table 248-1 Chronic Kidney Disease Staging System
|Stage||Description||GFR (ml/min/1.73 m2)|
|0||At increased risk||> 90|
|1||Kidney damage with normal or increased GFR||≥ 90|
|2||Kidney damage with mild decrease in GFR||60–89|
|4||Severe decrease in GFR||15–29|
|5||Kidney failure||< 15 or dialysis|
As GFR is not readily measured, mathematical formulae are used to estimate it. Both the Cockcroft-Gault and the Modification of Diet in Renal Disease (MDRD) formulas are commonly used, with many laboratory reports listing estimated GFR (eGFR) (Table 248-2). The Cockcroft-Gault formula is simple, but often overestimates kidney function. The MDRD is a more arduous calculation, but is more accurate in patients with advanced CKD. However, it underestimates GFR in patients with near-normal sCr. These formulas are only useful when sCr is in a steady state. When the sCr is rapidly changing, as in acute kidney injury, they ...