Is a percutaneous ultrasound‑guided renal biopsy indicated and safe in a patient with suspected IgA nephropathy who has persistent hematuria, proteinuria >0.5 g/day and declining estimated glomerular filtration rate, provided blood pressure is <140/90 mm Hg, international normalized ratio <1.5 and platelet count >100 ×10⁹/L?

Kidney Biopsy in Suspected IgA Nephropathy

Yes, percutaneous ultrasound-guided renal biopsy is strongly indicated and safe in this patient with suspected IgA nephropathy who meets all the clinical and safety criteria outlined.

Primary Indication for Biopsy

Adults with suspected IgA nephropathy and proteinuria ≥0.5 g/day should undergo kidney biopsy to confirm the diagnosis. 1 The kidney biopsy is the gold standard for diagnostic evaluation of glomerular diseases and is essential for the diagnosis of IgA nephropathy. 2, 3

Your patient meets clear diagnostic criteria with:

• Persistent hematuria (glomerular origin suspected)
• Proteinuria >0.5 g/day (exceeds the threshold)
• Declining estimated glomerular filtration rate (progressive disease)

These findings cannot reliably distinguish IgA nephropathy from other glomerular diseases without tissue diagnosis. 2

Safety Profile Confirmed

This patient meets all safety parameters for percutaneous biopsy:

• Blood pressure <140/90 mm Hg: Adequate for procedure safety, though optimal BP control to <120/70 mm Hg is a therapeutic target post-diagnosis. 1
• INR <1.5: Normal coagulation parameters minimize bleeding risk. 4
• Platelet count >100 ×10⁹/L: Sufficient for safe biopsy. 4

The complication rate of kidney biopsy is acceptably low, with major complications requiring intervention occurring in only 0.032-0.7% of cases. 4, 5 The overall bleeding risk is approximately 4%, which does not increase in patients with chronic kidney disease. 6, 5

Critical Diagnostic and Prognostic Value

The biopsy provides essential information that cannot be obtained clinically:

• Confirms IgA-dominant immune deposits in the glomerular mesangium, which is required to diagnose primary IgA nephropathy. 1
• Excludes mimics such as IgA vasculitis, IgA-dominant infection-related glomerulonephritis, and secondary IgA nephropathy from cirrhosis, inflammatory bowel disease, or autoimmune diseases. 1
• Provides prognostic information through the Oxford MEST score (mesangial hypercellularity, endocapillary hypercellularity, segmental glomerulosclerosis, tubular atrophy/interstitial fibrosis), which adds independent prognostic value. 2
• Identifies high-risk features such as crescentic disease (>50% of glomeruli with crescents), which would require aggressive immunosuppression with steroids and cyclophosphamide. 2

Technical Requirements

The biopsy must obtain at least 8-10 glomeruli to diagnose or exclude specific histopathologic patterns with reasonable confidence. 2, 6 Evaluation should include:

• Light microscopy with special stains (PAS, H&E, trichrome, Jones' silver)
• Immunohistology for IgG, IgA, IgM, C3, C4, C1q, fibrin, κ and λ light chains
• Electron microscopy for ultrastructural assessment 2, 6

Treatment Implications

The biopsy result directly determines treatment intensity. Based on KDIGO 2025 guidelines for IgA nephropathy management, patients with proteinuria >0.5 g/day require:

• Behavioral modifications (dietary sodium <2 g/day, smoking cessation, weight control)
• Antihypertensive therapy targeting BP <120/70 mm Hg
• Therapies to reduce IgA-immune complex formation (targeted-release budesonide)
• Potential systemic glucocorticoids or iptacopan for glomerular injury reduction
• Renin-angiotensin system inhibitors or dual endothelin angiotensin receptor antagonists (sparsentan) with or without SGLT2 inhibitors 1

The specific histologic findings (Oxford classification, presence of crescents, degree of chronicity) will guide whether immunosuppression is warranted, as patients with crescentic IgA nephropathy require aggressive therapy analogous to ANCA vasculitis. 2

Common Pitfalls to Avoid

Do not delay biopsy based on the presence of declining renal function alone. The absence of cortical atrophy or hyperechogenicity on ultrasound actually strengthens the indication for biopsy, as these findings indicate potentially reversible disease. 5

Do not assume all hematuria and proteinuria in this clinical context is IgA nephropathy. Up to 45% of patients with suspected monoclonal gammopathy-related disease do not actually have the suspected disorder on biopsy. 4 Similarly, clinical features alone cannot reliably predict histologic diagnosis in glomerular diseases. 5

Limiting needle passes to ≤4 reduces bleeding risk without compromising diagnostic yield. 6, 4