Papillary necrosis of the kidneys affects proper function of the kidneys, potentially leading to kidney failure. The kidneys are important in the body's ability to filter and remove waste from the blood, where the body can then remove it via the urine.

The papillae are an area of the kidneys that are key in the filtering function of the kidney. Renal papillary necrosis is the death of this tissue and more in the kidneys, reducing function and potentially resulting in kidney failure. The papillae are where the openings of the collecting ducts enter the kidney and then urine flows through to the ureters.¹ 

Causes of Papillary Necrosis

Papillary necrosis is caused due to things that damage the liver, this can be from a prior medical condition or due to a use of substances that are nephrotoxic (toxic to the kidneys).

The most common causes are:

• Overuse of pain medication - Particularly NSAIDs that cause damage to the kidneys
• Diabetes Mellitus- Damage is caused to the vasculature (blood vessels) of the kidneys
• Sickle cell anaemia - Damage caused due ue to altered blood/oxygen supply to the kidneys because of sickle cell²
• Urinary tract blockage - The tract is blocked causing damage or there is an infection (UTI)

Less common causes are of renal papillary necrosis are:

• Renal tuberculosis - TB found outside of the lungs
• Rejection of a renal transplant
• Renal vein thrombosis - Blockage in the vessel that takes blood away from the kidney

All these causes can lead to a loss of kidney function and eventual death of the tissue in the renal papillae, further affecting renal function.³ 

Symptoms of Papillary Necrosis

There are several symptoms that are similar to that of many other kidney conditions, and it can be hard to identify papillary necrosis early on. As the condition develops the symptoms are:

• Back/flank pain (in kidney area)
• Dark, cloudy or bloody urine
• Pain whilst urinating
• More regular need to urinate, and needing to urinate through the night

These are the most common symptoms that would suggest to a doctor a diagnosis of papillary necrosis as these are clear signs of reduced renal function.⁴ 

Those with papillary necrosis are also more likely to develop urinary tract infections (UTIs) on a more regular basis than those with healthy, functional kidneys.

As papillary necrosis develops it can cause chronic kidney disease and eventual kidney failure, If the infections do develop and the kidneys do fail, however, death can occur.

Diagnosing Papillary Necrosis

When the symptoms are present a doctor can have an idea of the diagnosis of some renal disorder, though further tests would be required to confirm papillary necrosis.

The tests may include looking directly at the state of the kidney, including: 

• Contrast MRI - Dye is used to show the state of the kidney during an MRI
• Ureteroscopy- A camera is used to view the inside of the kidney
• Kidney biopsy- A small amount of kidney tissue is removed to be viewed and assessed

These tests all look at the kidney and its current health and structure and can be used by a doctor to inform a diagnosis of papillary necrosis.

Other tests can be done to test the function of the kidneys, which test  whether the kidneys are filtering as they should, these include :

• High blood nitrogen levels which show that the kidneys are not filtering as they should
• Creatinine (a product of muscles breaking down) is normally cleared, but high levels would show kidneys are not filtering correctly
• Estimated glomerular filtration rate (eGFR) - is a calculation of the level of proteins in the blood, and how well the kidneys function
• Urinalysis- Assessing and testing urine for proteins and blood cells that should not be present; there may even be some renal papillae tissue

All these test can show what there is an issue with the kidneys and the way they filter, and would be helpful for a doctor to diagnose papillary necrosis.³ 

Treatment

Treatment for papillary necrosis varies based on each case, its causes and the level of damage that has occurred.

If caused by overuse of painkillers, it will be recommended that they stop using painkillers to allow the kidneys to heal.

In those with Diabetes Mellitus, the disease will have to be managed very closely. There would be hope that the kidneys can heal on their own as long as the root cause is addressed. In those with severe necrosis; kidney infections and potential kidney failure can occur, which would require dialysis treatment to perform the filtering that the kidneys cannot or in the most severe of cases kidney transplant is an option.⁵ 

Summary

Papillary necrosis is a disorder of the kidneys that can seriously affect renal function and potentially end in kidney failure. The renal papillae are areas of the kidney where urine is collected before going through the ureters into the bladder. In papillary necrosis, the cells and tissue of this area die, reducing renal function.

The main causes of papillary necrosis are overuse of over the counter pain medication; particularly NSAIDs, and those with diabetes mellitus are more common sufferers. Those with papillary necrosis are more likely to suffer from urinary tract infections and these can then result in kidney failure and potential death.

The symptoms of papillary necrosis are similar to that of many kidney disorders, the most common of which are:

• Severe flank pain (in area of kidneys)
• Cloudy, dark urine, potentially containing blood
• Pain whilst urinating
• Urinary tract infections (UTI)
• Frequent need to urinate through the night

Treatment is dependent upon the cause where if the disease is caused by painkiller overuse; this medication will be discontinued and the person monitored. Those with necrosis caused by diabetes mellitus will have their condition monitored closely also. There would be hope that as the root cause is addressed, the kidney may heal as time passes of course this requires that there not be too much damage done over the course of the disease.

In the more extreme cases where there is kidney failure, dialysis may be used as treatment to filter the waste that the kidney cannot, and in the most severe cases a kidney transplant may be required.