What Is Renal Papillary Necrosis?

Have you ever imagined a little waterfall or a tiny faucet in your body where water flows? Yes! The renal papillae in the kidneys are the body’s tiny faucets. The kidneys are a paired organ in the body that remove waste products from the blood. In each kidney, the renal artery (a blood vessel that carries blood to the kidney) divides into tiny blood vessels, from which waste products are filtered in the middle of the kidney. This middle region is called the renal medulla, which contains numerous cistern-like renal pyramids with renal papillae at their terminal ends acting like faucets to empty urine into a bigger vessel, which leads to the ureter and travels to the bladder before being let out through the urethra.

Renal papillary necrosis is a condition where all or part of the cells of the renal papillae die and are unable to perform their functions. For water to flow into the sink, the faucet must be functional due to the efficiency of its moving parts. The renal papillae stay alive and functional when blood flows to their cells to give them nutrients, but when blood flow is disrupted, these cells begin to die, and when normal blood flow isn’t restored, they all die eventually.

The death of the cells and tissues of the renal papillae in the kidneys results in renal papillary necrosis. With this condition, there is reduced kidney function and eventual kidney failure.

Overview 

The kidneys play many vital roles in your body, particularly filtering the blood, helping to remove harmful waste products and maintaining fluid levels. Inside the kidneys are complex cable-like functional units known as nephrons, whose tubules terminate by emptying into the pelvis through the renal papillae.

Renal papillary necrosis is a health condition that affects the renal papillae of the kidneys.

• Renal refers to the kidney
• Papillary refers to the papillae (small, nipple-like bumps in the middle region (medulla) of the kidney)
• Necrosis refers to the death of cells or tissues

From the outline above, renal papillary necrosis is understood to be the irreversible death of the cells or tissues of the renal papillae. When the cells of the renal papillae die, they slough off, which may result in reduced renal function and, ultimately, renal failure. 

Causes of renal papillary necrosis

Renal papillary necrosis is caused by different conditions and factors. Major causes of renal papillary necrosis include:

• Diabetes mellitus
• Analgesic nephropathy: It is the inflammation of the kidney tubules caused by chronic use of analgesic drugs like acetaminophen (paracetamol), aspirin, phenacetin and NSAIDs
• Sickle cell disease: A condition where the presence of sickle cell trait produces sickle-shaped red blood cells which block tiny blood vessels like the ones that supply the papillae
• Prolonged use of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) like ibuprofen, diclofenac, naproxen, indomethacin

Other conditions that could cause renal papillary necrosis include:

• Pyelonephritis: A kidney infection caused by bacteria from a bladder infection
• Obstructive uropathy: Urinary tract obstruction could cause total or partial hindrance to normal urine flow, causing inflammation
• Chronic liver disease¹
• Tuberculosis: Renal tuberculosis is caused by the spread of the bacteria through blood or lymphatics to the kidneys and destroys the cells of renal papillae
• Systemic vasculitis: It is the inflammation of blood vessels which results in the reduction of blood flow to renal papillae
• Renal transplant rejection: The body’s antibodies launch an attack on the transplanted kidney²

Signs and symptoms of renal papillary necrosis

The absence of noticeable signs and symptoms at the early stage makes the diagnosis of renal papillary necrosis challenging. As it progresses, the following symptoms manifest:

• Painful urination
• Frequent urination at night
• Haematuria, bloody urine or dark-coloured urine
• Cloudy urine
• Severe back or flank pain
• Fever and chills
• Urinary incontinence (unintentional passing of urine)
• Pyuria (presence of pus in the urine)
• Ureteral colic: Severe pain due to ureteric obstruction caused by kidney stones
• Presence of necrotic papillae in urine, like pieces of tissue in urine

If renal papillary necrosis is left untreated, it can result in chronic kidney disease and, eventually, kidney failure. Renal papillary necrosis, when complicated by infection, may lead to death.

Diagnosis of renal papillary necrosis

Your healthcare provider will conduct the following tests to diagnose renal papillary necrosis:

• Urography: You will receive an IV dye (contrast) followed by imaging tests like X-rays, MRI or CT Scan. Imaging after the administration of dye helps your healthcare provider see the damaged areas of the kidney
• Urinalysis: Your urine sample is screened for underlying health conditions like diabetes, urinary tract infection (UTI), etc
• Cystoscopy: A thin, flexible tube with a camera is inserted into your to look inside the  urethra and bladder for damages
• Ureteroscopy: A thin, flexible tube with a camera is inserted into your to look inside the ureters and kidneys for damages. The tube is longer and thinner than the one used for cystoscopy
• Urine protein/creatinine ratio: This is a blood test that looks for protein in your blood and acts as an indicator of kidney damage

Management and treatment for renal papillary necrosis

There is no specific treatment for renal papillary necrosis, but the condition can be managed by treating the underlying cause. For instance, renal papillary necrosis caused by diabetes can be managed when diabetes is treated, halting the progression of papillary necrosis.

The preservation of renal papillary tissue or the effectiveness of interventions to halt the progression of tissue death depends on the severity of the condition. If the cause can be intercepted, the condition may improve, but in severe cases, it may lead to renal failure, which requires a kidney transplant.

FAQs

How can I prevent renal papillary necrosis?

To prevent renal papillary necrosis, you have to control the cause (for example, diabetes or sickle cell disease) and follow your doctor’s instructions on the use of analgesics. Controlling these factors may reduce your risk.

Who is at risk of renal papillary necrosis?

Renal papillary necrosis has been reported to commonly affect the elderly (>60 years) and those assigned female at birth. Diabetic and sickle cell anaemia patients are at risk of developing renal papillary necrosis.

When should I see a doctor?

You should see a doctor when you release bloody urine and when you notice other symptoms of renal papillary necrosis, particularly after taking over-the-counter pain medicines.

Summary

Renal papillary necrosis is a condition where the cells of the renal papillae die, resulting in reduced kidney function and potential kidney failure. Various factors, including diabetes, abuse of analgesics, sickle cell disease, prolonged use of NSAIDs, kidney infections, urinary tract obstruction, chronic liver disease, tuberculosis, systemic vasculitis, and renal transplant rejection, cause this condition. You might not experience any symptoms during the early stages of renal papillary necrosis, but as it progresses, you might experience painful and frequent urination, bloody or dark-coloured urine, severe back or flank pain, fever, and urinary incontinence. Please visit your healthcare provider if you experience any of these symptoms. Your healthcare provider will diagnose this condition through various tests such as urine cytology, urography, urinalysis, ureteroscopy, and cystoscopy. Renal papillary necrosis cannot be treated directly; treatment involves managing the underlying cause and, in severe cases, may require a kidney transplant. You can prevent renal papillary necrosis by managing the underlying causes like diabetes or sickle cell disease and also by following instructions when using analgesics.