Do glomerular diseases fall under acute kidney injury (AKI) or chronic kidney disease (CKD)?

Glomerular Diseases in Kidney Disease Classification

Glomerular diseases can present as either acute kidney injury (AKI) or chronic kidney disease (CKD), depending on their onset, duration, and progression. 1, 2

Classification Framework

• Glomerular diseases are classified based on their temporal presentation and progression pattern within the kidney disease continuum that includes AKI, Acute Kidney Disease (AKD), and CKD 1, 3
• AKI is defined as kidney dysfunction occurring over less than 7 days, characterized by rapid increases in serum creatinine or decreased urine output 4
• AKD represents kidney dysfunction present for 7 days to 3 months, bridging the gap between AKI and CKD 3, 4
• CKD is defined as kidney dysfunction persisting for more than 3 months 3, 4

Glomerular Diseases as AKI

• Rapidly progressive glomerulonephritis (RPGN) is a classic example of glomerular disease presenting as AKI, with rapid deterioration of kidney function over days to weeks 2
• Both crescentic and non-crescentic forms of acute glomerulonephritis can present as AKI 2
• Heavy proteinuria and macroscopic hematuria from glomerular diseases can directly contribute to the development of AKI 2
• Acute nephritic syndrome with glomerular inflammation can cause rapid decline in kidney function meeting AKI criteria 2

Glomerular Diseases as CKD

• When glomerular diseases persist beyond 3 months with ongoing kidney dysfunction, they are classified as CKD 1, 3
• Chronic glomerulonephritis is a common cause of CKD, characterized by persistent proteinuria, hematuria, and progressive decline in GFR 3
• The CKD classification system recommends cause-specific classification (including glomerular diseases) in combination with GFR and albuminuria staging 1

Transition Between AKI and CKD in Glomerular Diseases

• Glomerular diseases may initially present as AKI but transition to CKD if kidney function does not recover within 3 months 1, 5
• The concept of AKD has been proposed to bridge the gap between AKI and CKD, encompassing conditions like ongoing glomerular diseases that don't meet strict criteria for either 4, 5
• Maladaptive repair mechanisms following glomerular injury can promote progression from AKI to CKD through endothelial cell injury, inflammatory reactions, and fibrosis 6

Diagnostic Approach

• Diagnosis of glomerular diseases underlying AKI requires a high degree of suspicion and an algorithmic approach to laboratory investigations 2
• Renal biopsy represents the gold standard for diagnosing glomerular diseases, whether presenting as AKI or CKD 2
• Invasive diagnostic workup (kidney biopsy) should be considered for unresolving AKI/AKD, which might be due to underlying glomerular disease 1

Management Considerations

• Management of glomerular diseases differs based on whether they present as AKI, AKD, or CKD 1, 3
• For glomerular diseases causing AKI, immediate interventions focus on treating the underlying cause and preventing further kidney damage 3
• For glomerular diseases causing CKD, long-term strategies focus on slowing progression and managing complications 3
• Medication dosing should be adjusted based on current kidney function in patients with glomerular diseases 1, 7

Common Pitfalls

• Failing to recognize that glomerular diseases can present across the spectrum of kidney disease (AKI, AKD, and CKD) 2, 5
• Overlooking the need for kidney biopsy in cases of unexplained AKI, which may reveal underlying glomerular pathology 1, 2
• Underestimating the risk of progression from AKI to CKD in patients with glomerular diseases 8, 9
• Neglecting to monitor patients with resolved glomerular-related AKI, who remain at risk for CKD development 8, 9