Renal papillary necrosis
Renal papillary necrosis, also known as RPN, is a condition in which some or all of the renal papillae die. Renal papillae are located where the collecting ducts enter the kidneys and where urine enters the ureters. Complications of renal papillary necrosis include kidney infections, renal calculi (kidney stones), complete renal failure, and even kidney cancer.
Definition & Facts
Renal papillary necrosis was first described in 1877 in a patient who suffered a urinary tract obstruction resulting from an enlarged prostate. The majority of cases of RPN occur in patients with diabetes, severe urinary obstructions, or those who abuse analgesic pain medications.
A translation of the autopsy notes of German composer Ludwig von Beethoven, who died 50 years before the first description of RPN, suggests that the musical genius may have died from the condition. The autopsy notes describe physical changes to the kidneys indicative of RPN.
Beethoven developed diabetes, liver cirrhosis, and chronic pancreatitis as a result of long-term alcoholism and a viral hepatitis infection. He also suffered debilitating headaches, gout or rheumatism, and back pain for which he frequently took an analgesic made from willow bark. All of these factors may have worked together to cause renal papillary necrosis.
Symptoms & Complaints
- Painful urination
- Chills or fever
- Frequent or urgent urination
- Frequent nighttime urination
- Urinating in large amounts
- Problems starting or maintaining urination
- Urinary incontinence
Since most causes of renal papillary necrosis are systemic in nature, the condition normally affects both kidneys. Most patients who initially develop RPN in one kidney will go on to develop the condition in the other kidney within a few years. True unilateral renal papillary necrosis normally only occurs in cases where the causative factor is an obstruction or infection affecting only one kidney.
Analgesic nephropathy is one of the most common causes of renal papillary necrosis. Analgesic nephropathy is a type of kidney damage resulting from overexposure to pain medications. This is most often seen in cases of long-term or excessive use of over-the-counter analgesics such as nonsteoridal anti-inflammatory drugs (NSAID's) like ibuprofen as well as acetaminophen and aspirin.
Patients most at risk for developing analgesic nephropathy are those who use over-the-counter pain medications with more than one ingredient, who take six or more pain pills a day for a long period, suffer from chronic pain, and who have a history of substance abuse.
Children with sickle-cell anemia are also susceptible to developing RPN. Sickle-cell anemia is a condition caused by an abnormal form of hemoglobin, which is the protein found in red blood cells responsible for carrying oxygen throughout the body. Sickle-cell anemia is most common among individuals of African or Mediterranean descent, but it can also occur in people from the Caribbean, Central and South America, and the Middle East.
Diagnosis & Tests
A physical examination will typically reveal flank tenderness near the kidneys. The patient may also report a history of urinary tract infections or obstructions. Laboratory tests, including a complete blood count, metabolic panel, and measurement of blood clotting times may be used to evaluate kidney function and to rule out other health conditions.
A urinalysis, urine cytology, and urine culture may be used to rule out infections, tumors, and other potential causes of blood in the urine. The urinalysis will typically reveal the presence of protein, bacteria, and pus in the urine and a low urine specific gravity suggesting possible renal failure.
The urine may also show elevated levels of nitrogen compounds and white blood cells. A cystoscopy or ureteroscopy may be used to explore the bladder and upper urinary tract for tumors or other defects. In cases of a suspected urinary tract obstruction, an ultrasound, computed tomography (CT) scan, or another type of radiographic evaluation may be used to identify the type and location of the blockage.
Treatment & Therapy
Treatment for renal papillary necrosis depends on the underlying cause. Patients with analgesic-induced RPN should stop taking analgesics immediately. Depending on the extent of damage, the kidney may heal and regain some function with time.
Patients whose condition is caused by a renal obstruction will typically require surgery to remove the source of the blockage. This may include creating an opening between the kidney and the skin to divert the flow of urine, endoscopic surgery to address the obstruction, or the placement of a stent in the ureters.
Patients with a urinary obstruction may also require medications to treat associated infections and alkalinize the urine. Patients who experience enough blood in their urine to cause anemia may need to undergo blood transfusions. Exchange blood transfusions may also be necessary for patients with necrosis resulting from sickle-cell anemia.
Insulin therapy may help diabetic patients regain a normal glycemic balance. In some cases, the kidney function is impaired to the point that the patient requires dialysis to remove waste from the blood and ultimately a kidney transplant to replace the damaged kidney with a functioning kidney from a healthy donor.
Prevention & Prophylaxis
Individuals who notice blood in their urine, a change in urinary patterns, or any other symptoms of renal papillary necrosis should see their doctor as soon as possible for a diagnosis.
The prognosis for those with the condition varies depending on the extent of the necrosis, whether one or both kidneys are involved, and the age and overall health of the patient. The prognosis is generally poor for elderly patients with multiple comorbidities and those with uncontrolled diabetes.