| Definition: |
| Chronic kidney disease is defined based on the presence of either kidney damage or decreased kidney function for three or more months, irrespective of cause. |
| Criteria | Comment |
| Duration ≥3 months, based on documentation or inference | Duration is necessary to distinguish chronic from acute kidney diseases. - Clinical evaluation can often suggest duration
- Documentation of duration is usually not available in epidemiologic studies
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| Glomerular filtration rate (GFR) <60 mL/min/1.73 m2 | GFR is the best overall index of kidney function in health and disease. - The normal GFR in young adults is approximately 125 mL/min/1.73 m2; GFR <15 mL/min/1.73 m2 is defined as kidney failure
- Decreased GFR can be detected by current estimating equations for GFR based on serum creatinine (estimated GFR) but not by serum creatinine alone
- Decreased estimated GFR can be confirmed by measured GFR, measured creatinine clearance, or estimated GFR using cystatin C
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| Kidney damage, as defined by structural abnormalities or functional abnormalities other than decreased GFR | Pathologic abnormalities (examples). Cause is based on underlying illness and pathology. Markers of kidney damage may reflect pathology. - Glomerular diseases (diabetes, autoimmune diseases, systemic infections, drugs, neoplasia)
- Vascular diseases (atherosclerosis, hypertension, ischemia, vasculitis, thrombotic microangiopathy)
- Tubulointerstitial diseases (urinary tract infections, stones, obstruction, drug toxicity)
- Cystic disease (polycystic kidney disease)
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History of kidney transplantation. In addition to pathologic abnormalities observed in native kidneys, common pathologic abnormalities include the following: - Chronic allograft nephropathy (non-specific findings of tubular atrophy, interstitial fibrosis, vascular and glomerular sclerosis)
- Rejection
- Drug toxicity (calcineurin inhibitors)
- BK virus nephropathy
- Recurrent disease (glomerular disease, oxalosis, Fabry disease)
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Albuminuria as a marker of kidney damage (increased glomerular permeability, urine albumin-to-creatinine ratio [ACR] >30 mg/g).* - The normal urine ACR in young adults is <10 mg/g. Urine ACR categories 10-29, 30-300 and >300 mg are termed "mildly increased, moderately increased, and severely increased" respectively. Urine ACR >2200 mg/g is accompanied by signs and symptoms of nephrotic syndrome (low serum albumin, edema and high serum cholesterol).
- Threshold value corresponds approximately to urine dipstick values of trace or 1+, depending on urine concentration
- High urine ACR can be confirmed by urine albumin excretion in a timed urine collection
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Urinary sediment abnormalities as markers of kidney damage, for example: - RBC casts in proliferative glomerulonephritis
- WBC casts in pyelonephritis or interstitial nephritis
- Oval fat bodies or fatty casts in diseases with proteinuria
- Granular casts and renal tubular epithelial cells in many parenchymal diseases (non-specific)
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Imaging abnormalities as markers of kidney damage (ultrasound, computed tomography and magnetic resonance imaging with or without contrast, isotope scans, angiography). - Polycystic kidneys
- Hydronephrosis due to obstruction
- Cortical scarring due to infarcts, pyelonephritis or vesicoureteral reflux
- Renal masses or enlarged kidneys due to infiltrative diseases
- Renal artery stenosis
- Small and echogenic kidneys (common in later stages of CKD due to many parenchymal diseases)
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