From the Guidelines
Chronic kidney disease (CKD) is defined as persistent abnormalities of kidney structure or function, present for a minimum of three months, characterized by a glomerular filtration rate (GFR) below 60 mL/min/1.73m² or evidence of kidney damage, such as albuminuria, that persists for three months or longer. This definition is based on the most recent and highest quality study available, which emphasizes the importance of early detection and management of CKD to slow progression and prevent complications 1. The disease is classified into five stages based on GFR levels, with stage 1 being the mildest and stage 5 (kidney failure) being the most severe. Common causes of CKD include:
- Diabetes
- High blood pressure
- Glomerulonephritis
- Polycystic kidney disease
- Recurrent kidney infections
Early CKD often has no symptoms, but as it progresses, patients may experience:
- Fatigue
- Swelling in legs and ankles
- Itching
- Muscle cramps
- Changes in urination
- Nausea
- Decreased appetite
The definition of CKD has been refined over time, with earlier studies emphasizing the importance of kidney damage or decreased GFR for three months or longer 1. More recent studies have highlighted the importance of albuminuria as a marker of kidney damage, with persistent albuminuria defined as urinary albumin excretion >30 mg/24 h or urinary albumin to creatinine ratio (UACR) >30 mg/g 1. The most recent study, published in 2024, provides a comprehensive definition of CKD and emphasizes the importance of early detection and management to improve patient outcomes 1.
From the Research
Definition of Chronic Kidney Disease
- Chronic kidney disease (CKD) is a long-term condition characterized by gradual loss of kidney function over time 2.
- The definition and classification of CKD have evolved over time, but current international guidelines define this condition as decreased kidney function shown by glomerular filtration rate (GFR) of less than 60 mL/min per 1·73 m2, or markers of kidney damage, or both, of at least 3 months duration, regardless of the underlying cause 3.
- CKD is generally regarded as a final common pathway of several renal diseases, often leading to end-stage kidney disease (ESKD) and a need for renal replacement therapy 4.
Key Characteristics
- The best available indicator of overall kidney function is GFR, which is measured either via exogenous markers or estimated using equations 3.
- Presence of proteinuria is associated with increased risk of progression of CKD and death 3.
- Kidney biopsy samples can show definitive evidence of CKD, through common changes such as glomerular sclerosis, tubular atrophy, and interstitial fibrosis 3.
Diagnosis and Progression
- Diagnosis is commonly made after chance findings from screening tests (urinary dipstick or blood tests), or when symptoms become severe 3.
- A decline in estimated GFR is a significant predictor of subsequent risk of end-stage renal disease and mortality 5, 6.
- A 40% decline in estimated GFR is broadly acceptable as a kidney end point across a wide baseline eGFR range, and a 30% decline may be acceptable in some situations 5.