Chronic kidney disease (CKD) is a progressive disease staged on the patient's glomerular filtration rate (GFR) and presence of albuminuria. The National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI) and the global non-profit foundation, Kidney Disease: Improving Global Outcomes (KDIGO), define CKD as: (1) pathological abnormalities or markers of kidney damage such as proteinuria present for 3 months or more with or without a decreased GFR, or (2) a GFR less than 60 mL/min/1.73 m2 for 3 months or more. Staging of CKD identifies patients at higher risk of worsening clinical manifestations and disease complications. Stages are determined by GFR and albuminuria categories. See Table 35-1 for CKD staged by GFR. Albuminuria is categorized as A1, A2, or A3 by urine albumin-to-creatinine ratio (ACR) as mg/g or urinary albumin excretion rate (AER) as mg/24 hour.
A1 is less than 30 ACR or AER (normal to mildly increased protein).
A2 is 30 – 300 ACR or AER (moderately increased).
A3 is greater than 300 ACR or AER (including nephrotic syndrome) (severely increased).
TABLE 35-1Glomerular Filtration Rate Categories Based on KDIGO Classification ||Download (.pdf) TABLE 35-1 Glomerular Filtration Rate Categories Based on KDIGO Classification
|GFR Categorya ||GFR (mL/min/1.73 m2) ||Terms |
|1 ||>90 ||Normal or high |
|2 ||60-89 ||Mildly decreased |
|3a ||45-59 ||Mildly to moderately decreased |
|3b ||30-44 ||Moderately to severely decreased |
|4 ||15-29 ||Severely decreased |
|5 ||<15 ||Kidney failure |
Kidney failure is defined as: (1) a GFR less than 15 mL/min/1.73 m2 or (2) a need for renal replacement therapy (RRT) such as continuous renal replacement therapy (CRRT), intermittent hemodialysis (IHD), peritoneal dialysis (PD), or kidney transplantation to maintain renal homeostasis and avoid complications. End-stage renal disease (ESRD) is an administrative term recognized by the Medicare ESRD Program that determines reimbursement conditions for health care of patients with this condition. ESRD includes patients treated by dialysis or transplantation, irrespective of the level of GFR.
Diabetes mellitus (DM) and hypertension (HTN) are the most common causes of CKD. Diabetic nephropathy is thought to be caused by vascular changes from chronic hyperglycemia. Renal afferent arteriole vasodilation is hypothesized to result from hyperglycemia and high insulin-like growth factor-1 (IGF-1) concentrations resulting in glomerular hyperfiltration. Alterations in hemodynamics, solute transport, and growth factors eventually cause proteinuria and an inflammatory process which results in activation of the renin angiotensin aldosterone system (RAAS), fibrosis, and loss of renal function. HTN is both a cause and a complication of CKD. HTN is a risk factor for progression of kidney disease by accelerating proteinuria and activation ...