26th June 2023

Renal papillary necrosis

Pathophysiology of renal papillary necrosis

It is characterised by coagulative necrosis of the renal medullary pyramids and papillae due to ischaemia and toxins affecting the kidney. The whole papillary tip (which is the most susceptible portion of the pyramid) and the inner medulla are necrotic, however, the outer medulla is occasionally preserved. The renal papillae are located where the openings of the collecting ducts enter the kidney and where urine passes into the ureters. The blood supply is from the vasa recta, and it is often damage to this structure that leads to necrosis.

Its presentation can vary from asymptomatic to renal failure. Symptoms include Nocturia, dysuria, pyuria, haematuria (usually microscopic), ureteral colic, back or flank pain. Obstructive symptoms of flank pain and colic can occur due to sloughed papillary cells.

Causes of renal papillary necrosis

The acronym ‘POSTCARDS’ is useful to remember these:

• Pyelonephritis (acute)
• Obstructive uropathy
• Sickle cell disease
• Tuberculosis/tubulointerstitial nephritis
• Chronic liver disease
• Analgesics/alcohol
• Renal transplant rejection
• Diabetes mellitus (worst prognosis)
• Systemic vasculitis

Diagnosis

• Urinalysis: haematuria, pyuria, proteinuria, sloughed papillae.
• Histology: Coagulative necrosis of the renal papillae and the medullary pyramids. Necrotic region bordered by neutrophils in the interstitium.

Management

• Treat or manage the underlying cause.
• Manage renal function with supportive care and fluid resuscitation.
• Antibiotics if pyelonephritis is the cause of renal papillary necrosis.
• Prognosis depends on the underlying cause; diabetes and old age are associated with a worse prognosis.