What are the key indications for referring a patient for a renal biopsy in primary care?

In primary care, key indications for referring a patient for a renal biopsy generally align with criteria for specialist assessment of chronic kidney disease (CKD) where the underlying cause is unclear or when specific features suggest a potentially treatable or rare renal pathology. These indications include:

• Significant proteinuria: An albumin-to-creatinine ratio (ACR) of 70 mg/mmol or more, unless already known to be caused by diabetes and appropriately treated.
• Moderate proteinuria with haematuria: An ACR of more than 30 mg/mmol (category A3) together with haematuria.
• Rapid decline in kidney function: A sustained decrease in estimated glomerular filtration rate (eGFR) of 25% or more and a change in eGFR category within 12 months, or a sustained decrease in eGFR of 15 ml/min/1.73 m2 or more per year.
• Poorly controlled hypertension: Hypertension that remains above the individual target despite the use of at least four antihypertensive medicines at therapeutic doses.
• Known or suspected rare or genetic causes of CKD.
• Suspected renal artery stenosis.

These features warrant referral to nephrology where a renal biopsy may be considered to establish diagnosis and guide management ¹.