Definition
Renal papillary necrosis is ischaemic necrosis of the renal papillae — the innermost part of the medulla, which has a relatively precarious blood supply and is therefore vulnerable to ischaemic and toxic insults.
Causes
- Analgesic nephropathy (chronic NSAID/analgesic use)
- Diabetes mellitus
- Sickle cell disease (and trait)
- Severe pyelonephritis
- Urinary obstruction
- Tuberculosis; cirrhosis
Clinical presentation
- Haematuria (visible or non-visible)
- Loin pain, sometimes renal colic as sloughed papillae pass
- Recurrent urinary infections; sloughed tissue may cause obstruction
- Features of the underlying disease
Investigations
- Urinalysis (haematuria); look for sloughed papillary tissue
- CT urography — clubbed calyces and "ring-shaped" filling defects where papillae have detached
- Assess renal function and treat the underlying cause
Management
- Treat the underlying cause (stop offending analgesics, optimise diabetes, manage sickle cell)
- Relieve any obstruction; treat infection
- Supportive care and monitoring of renal function
MRCP-specific traps
- Chronic analgesic use with haematuria and loin pain suggests papillary necrosis.
- Sickle cell disease and diabetes are classic exam causes.
- Passing sloughed tissue can mimic a stone (colic) and cause obstruction.
Summary
Renal papillary necrosis is ischaemic necrosis of the poorly-perfused renal papillae, caused by analgesics, diabetes, sickle cell disease, severe pyelonephritis, obstruction or TB. It presents with haematuria and loin pain, with clubbed/ring calyces on CT urography. Treat the underlying cause and any obstruction.
nephrologyurologymrcp part 2