Indications for Kidney Biopsy
Kidney biopsy should be performed when the diagnosis of kidney disease cannot be otherwise established and the biopsy result is expected to modify treatment and/or provide additional prognostic information needed for patient management. 1
Primary Indications
Glomerular Disease Evaluation
- Significant proteinuria (>1 g/day), especially with glomerular hematuria and/or cellular casts 1
- Unexplained decrease in glomerular filtration rate (GFR) 1
- Nephrotic syndrome without clear etiology 2
- Rapidly progressive glomerulonephritis 2
- Persistent isolated glomerular hematuria when other causes have been excluded 1
Cancer-Related Kidney Disease
- New-onset significant proteinuria (>1 g/day) in cancer patients 1
- Worsening kidney function in cancer patients when diagnosis cannot be otherwise established 1
- Evaluation of long-term consequences of systemic therapy and radiation-induced kidney toxicity in cancer survivors 1
Systemic Disease with Kidney Involvement
- Suspected lupus nephritis with reproducible proteinuria ≥0.5 g/24h, especially with glomerular hematuria and/or cellular casts 1
- Suspected monoclonal gammopathy of renal significance (MGRS) 1
- Unexplained acute kidney injury in hematopoietic stem cell transplant recipients 3
Biopsy Standards and Requirements
Tissue Adequacy
- At least 8-10 glomeruli needed to diagnose or exclude specific histopathologic patterns with reasonable confidence 1
- More tissue may be needed to accurately diagnose focal and segmental lesions 1
- Evaluation should include light microscopy, immunohistology, and electron microscopy 1
Timing Considerations
- Biopsy should be performed within the first month after disease onset, preferably before immunosuppressive treatment 1
- Treatment with high-dose glucocorticoids should not be delayed if renal biopsy cannot be readily performed in urgent cases 1
Situations Where Biopsy May Not Be Required
Specific Serological Markers
- PLA2R antibody-positive membranous nephropathy with nephrotic syndrome and normal eGFR 1
- MPO+ or PR3+ ANCA vasculitis 1
- Anti-glomerular basement membrane disease 1
Other Conditions
- Alport disease or familial focal segmental glomerulosclerosis in families with well-characterized mutations 1
- Fabry disease with characteristic clinical presentation 1
- Cancer patients with poor prognosis where the expected gain from diagnosis is less than the patient's expected survival 1
Special Considerations
High-Risk Patients
- Transjugular kidney biopsy is an option in high-risk patients with coagulopathy 1, 4
- Laparoscopic or open biopsy may be considered in specific situations 5, 4
- Risk of bleeding (major complication) is approximately 4%, which does not increase in patients with MGRS-associated renal lesions including amyloidosis 1
Age Considerations
- Older age (≥70 years) should not discourage biopsy as most MGRS-related renal diseases occur in patients >50 years 1
- Presence of MGUS in people <50 years, when accompanied by renal manifestations, deserves thorough evaluation including biopsy 1
Repeat Biopsy Indications
- When information will potentially alter the therapeutic plan or contribute to prognosis estimation 1
- To evaluate disease relapse or treatment response in specific conditions 1
- When patients initially treated based on seropositivity for antibodies (e.g., anti-PLA2R) do not follow the expected course 1
Common Pitfalls to Avoid
- Relying solely on clinical features without histopathological confirmation when diagnosis is unclear 5
- Delaying biopsy in rapidly progressive glomerulonephritis 2
- Assuming that all proteinuria in diabetic patients is due to diabetic nephropathy without considering other causes 1
- Failing to correlate imaging findings with clinical and laboratory data 6