Renal medullary necrosis

Introduction to renal medullary necrosis Renal medullary necrosis, also known as Renal Papillary Necrosis (RPN), necrotizing papillitis, is essentially the ischemic necrosis of the renal papilla and its adjacent renal medulla. This disease can occur in a variety of diseases, mainly caused by Chronic tubulointerstitial nephropathy, in these chronic tubulointerstitial nephropathy, the renal medullary lesions are often more serious, the basic lesion is the renal blood circulation damage, causing the limitation or pervasation of one or more renal pyramidal distal Avascular necrosis. basic knowledge Sickness ratio: 0.0001% Susceptible people: no special people Mode of infection: non-infectious Complications: uremia acute renal failure

Cause of renal medullary necrosis

(1) Causes of the disease

The disease is often associated with severe pyelonephritis, diabetes, urinary tract obstruction, analgesic nephropathy, especially preparations or poisoning containing phenacetin (Phenacetin), also seen in vascular disease, transplanted kidney rejection, sickle cell anemia , hyperuricemia, macroglobulinemia, allergic reactions, shock, excessive use of vasoconstrictor drugs such as norepinephrine, and other reports that long-term fat-free diet can also occur necrosis of the kidney, causing necrosis of the kidney include:

1. Diabetes: Diabetes is the most common disease associated with renal papillary necrosis, accounting for 50% to 60% of the reported RPN cases. Most cases of recurrent renal nipple necrosis are diabetic patients. The results of an intravenous pyelography study show: Of the patients with insulin-dependent diabetes mellitus who were examined, 25% had renal papillary necrosis.

2. Obstructive nephropathy: In large reports, obstructive nephropathy accounts for 15% to 40% of the cause of RPN.

3. Pyelonephritis: Severe pyelonephritis is one of the common causes of renal papillary necrosis, especially pyelonephritis in patients with diabetes or urinary tract obstruction. Because infection can be the cause of renal papillary necrosis, it is often complicated by RPN. It can also be secondary to diabetes, so the proportion of infection in the cause of renal papillary necrosis is difficult to determine.

4. Analgesic abuse: the abuse of analgesics, especially the analgesic mixture containing phenacetin and the application of large doses of other analgesics, can cause necrosis of the kidney. In the United States, analgesics account for the cause of RPN. 15% to 20%; in countries where analgesics are commonly abused, analgesics can account for 70% of the cause of RPN, and children with analgesics can also have renal papillary necrosis.

5. Vasculitis:

(1) Transplanted renal vasculitis: vasculitis caused by transplanted kidney rejection can block the blood vessels supplying the nipple, leading to nipple ischemic necrosis. In addition, the patient's primary diseases such as diabetes, sickle cell hemoglobin disease, etc. can also cause transplanted kidney nipples. Necrosis.

(2) Wegner granuloma.

(3) necrotizing vasculitis: including nodular polyarteritis, allergic vasculitis, microangiitis and the like.

6. Sickle cell hemoglobinopathy.

7. Liver disease: Liver disease, especially alcoholic liver disease, can cause necrosis of the kidney.

The nipple type is also called nipple necrosis, characterized by necrosis, demarcation and separation of the nipple. The nipple is swollen in the early stage of necrosis, the mucosa is normal, the renal pelvis is normal, and the progressive necrosis causes the mucosa to be lost. The nipple is irregular and the edges are blurred. The separation of necrotic nipples began to form sinus. The sinus angiography showed an arc shape. When the whole necrotic nipple was separated from normal tissue, the angiography showed a ring-shaped shadow around the necrotic nipple in the sinus. In a few cases, the necrotic nipple fell off to the renal pelvis. It can be found in the urine, but in most cases, the necrotic nipple does not fall off, but is absorbed or kept in the distance, after which the necrotic nipple is calcified or forms the core of the stone, such as the necrotic nipple is absorbed or detached, the angiography is normal. The nipple site forms a "sickle-like renal pelvis"; if the necrotic nipple is calcified in the original place, the angiography can show the annular shadow around the necrotic nipple in the sinus, the necrotic nipple that has fallen off, and the stones formed thereby, which can cause urinary tract obstruction.

Renal medullary necrosis can be limited to a few nipples or occur in many nipples, involving unilateral or bilateral kidneys. Most patients have kidney involvement. It has been reported that patients with RPN in one kidney develop another in the next 4 years. Nipple necrosis on one side of the kidney.

(two) pathogenesis

The main pathogenesis of renal medullary necrosis may be due to insufficient blood flow to the renal medulla due to various causes, leading to ischemic necrosis, such as microvascular disease caused by diabetes or blood flow disorder caused by sickle cell disease.

The occurrence of this disease is related to the anatomical and physiological characteristics of renal medullary pyramidal blood supply and renal ischemia, medullary papillary vasculopathy and infection. The blood flow of the kidney is 85%-90% distributed in the cortex, and the medulla only accounts for 10%~ 15%, the closer the blood supply to the renal papilla is, and the origin of the parietal nephrolithal small arteries from the small small blood vessels, affected by the medullary solute concentration and osmotic pressure gradient, the blood viscosity gradually increased Slow blood flow is a common site for ischemic necrosis; associated basic diseases such as diabetes, analgesic nephropathy, hyperuricemia, etc. can cause chronic interstitial nephritis and renal small vessel disease, analgesic nephropathy , sickle cell anemia, macroglobulinemia, etc. caused by high concentration of acidic substances in the nipple area and abnormal blood viscous, urinary tract obstruction, renal pelvis, renal pelvis and renal tubular pressure increase, these factors can lead to the marrow Severe ischemia and necrosis of the head of the granule, and increased susceptibility to bacterial invasion in the whole body and parts of the patient. It is easy to complicated with kidney and urinary tract infections, further aggravating renal pyramidal blood supply disorder and tissue necrosis. More than half of the kidney nipples are found clinically. There are two or more necrotic cases (such as diabetes with urinary tract infection), the more susceptible factors, the higher the incidence.

Renal medullary necrosis prevention

Mainly to actively look for the primary disease and timely effective treatment, strive to restore kidney function as soon as possible, in order to prevent the development of the disease leading to renal nipple necrosis stage, patients with a clear diagnosis, should rest fully, pay close attention to the treatment of traditional Chinese and Western medicine to delay the kidney The function deteriorated.

Renal medullary necrosis Complications uremia acute renal failure

Continuous renal tubular acidosis can cause progressive renal dysfunction, eventually leading to chronic renal failure, uremia; severe bilateral renal medullary necrosis can occur acute renal failure.

Renal medullary necrosis symptoms common symptoms chills, urine collapse, polyuria, pus, high fever

According to the onset of illness, it can be divided into acute, subacute and chronic. According to the pathological part, it can be divided into renal medulla and renal papilla. The patient is more than 40 years old, more women than men, and the child is rare. Necrosis, but hypoxemia, dehydration or sepsis caused by acute renal medullary necrosis, clinical manifestations depends on the site of necrosis, the number of affected nipples and the rate of necrosis development, acute renal medullary necrosis often in the above chronic On the basis of the disease, sudden onset, chills and fever, gross hematuria or different degrees of hematuria and pyuria, accompanied by urinary tract irritation and low back pain and other acute pyelonephritis, such as renal papillary necrosis tissue shedding or clot obstruction of the ureter causes colic And oliguria or even no urine, severe bilateral renal medullary necrosis can occur acute renal failure, rapid progression, poor prognosis, patients die more than sepsis or complications of acute renal failure.

Such patients often have local symptoms that are not obvious due to severe systemic conditions. Especially when patients have diabetes, urinary tract obstruction and cardiovascular disease, it is more difficult to diagnose in time. This type is mostly clinical; subacute patients are not as serious as the former or Rapid, long course of disease, up to weeks or months, necrotic nipple shedding produces urinary tract obstruction, renal colic is more common, and there are kidney tissue necrosis such as dysuria, shedding, symptoms of urinary tract, and oliguria And progressive renal insufficiency; chronic type occurs on the basis of chronic interstitial nephritis, insidious onset, the course of disease can be several years, clinically similar to chronic interstitial nephritis or recurrent chronic pyelonephritis, and Renal tubular dysfunction, such as polyuria, nocturia, decreased urine concentration and phenol red excretion rate, uric acid dysfunction caused by renal tubular acidosis, etc., may have continuous microscopic hematuria and pyuria and progressive renal dysfunction , eventually leading to chronic renal failure, uremia; also without clinical symptoms, occasionally in the excretory urography, or found in the post-mortem autopsy, some cases often accompanied by urinary tract Skin tumors.

Renal medullary necrosis

Urine test

Have hematuria, gross hematuria accounted for 20%, microscopic hematuria is 20% to 40%; such as a large number of hematuria combined with hemorrhagic anemia, need to do nephrectomy, 50% to 60% of patients with white blood cell urine; 80% of patients exist Moderate proteinuria, bacteriuria can occur in urinary tract infections, bacteriuria is positive, and urinary necrotic tissue is found in the urine.

B-ultrasound

The value of the examination is limited unless it is caused by obstructive nephropathy, which causes necrosis of the kidney or secondary necrotic papilla remains in the renal pelvis.

X-ray examination

(1) KUB plain film: early radiological examination may be negative, intravenous pyelography found that the contrast agent entered the incompletely detached kidney nipple, and (or) the nipple area of the kidney was found to have a sputum or plaque filling point, the contrast agent entered the nipple There is a "worm-like" change in the cavity after shedding, and/or the edge of the renal pelvis.

(2) X-ray inspection performance is:

1 nipple necrosis type: the earliest is the renal pelvis is relatively fuzzy, and because the renal pelvis is formed into a blind tube, the two blind tubes gradually combine, showing a "bow" or "circular" image during angiography; necrotic renal nipple into the renal pelvis Filling defects appear inside, and the nipple has a rod-like cavity. The necrotic nipple produces filling defects and proximal expansion in the ureter. When there is calcium salt around the necrotic nipple, circular calcification is visible on the plain piece.

2 medullary necrotic type: When the necrotic tissue is deep within the cone, when there is no communication with the renal pelvis, the angiography does not change, and the above phenomenon occurs only after the fistula formation is connected with the renal pelvis.

(3) IVP is the most valuable diagnostic method for this disease:

1 The kidney nipple has a ring shadow or defect.

2 medullary or nipple calcification shadow.

3 Kidney shadow reduction and irregular contours.

Diagnosis and differentiation of renal medullary necrosis

diagnosis

The diagnosis of this disease is mainly based on medical history, symptoms, urine necrotic tissue found in urine and X-ray findings, and should be diagnosed with non-necrotic acute pyelonephritis, renal tuberculosis, kidney stones and actinomycosis. The diagnostic criteria are:

1. Chronic interstitial nephritis, pyelonephritis, obstruction of the outlet of the collecting tube, upper urinary tract obstruction and other diseases.

2. Urine examination shows necrotic papillary tissue.

3. IVP kidney nipples have annular shadows or defects, medullary or nipple calcification shadows, kidney shadow reduction and irregular contours.

In patients with primary disease causing renal medullary necrosis, especially on urinary tract obstruction or severe tubulointerstitial nephropathy, fever, hematuria, acute low back pain, urinary tract cramps and urinary tract obstruction, or Long-term polyuria and nocturia should consider renal medullary necrosis, long-term polyuria and nocturia in diabetic patients, should not be considered as diabetic polyuria, should pay attention to the possibility of renal medullary necrosis, manifested as long-term polyuria Cases of nocturia should be differentiated from other chronic tubulointerstitial nephropathy (including renal medullary cystic disease), renal tubular acidosis, and diabetes insipidus.

Retrograde or antegrade pyelography is the main diagnostic tool for this disease. Renal biopsy can help to rule out glomerulonephritis and other interstitial nephritis. The necrotic kidney nipple can be found in the urine to diagnose RPN. In suspicious cases, all urine should be collected. Filter with filter paper or gauze to find the nipple tissue.

Patients should be diagnosed with diabetes, vasculitis, urinary tract obstruction, alcoholic liver disease, sickle cell hemoglobin disease, venous thrombosis, etc. For patients with renal papillary necrosis due to infection, the primary disease causing infection should be further examined, such as Diabetes, urinary tract obstruction, etc.

Analgesic nephropathy (AN) differential diagnosis of renal medullary necrosis and reflux nephropathy (RN) renal medullary necrosis.

Severe pyelonephritis, poor treatment, and progressive deterioration of renal function should consider the possibility of this disease, especially in patients with diabetes, urinary tract obstruction and a history of long-term analgesics.

Differential diagnosis

Need to be differentiated from chronic obstructive nephropathy, tuberculosis, medullary sponge kidney and other diseases that cause medullary calcification; cases with long-term polyuria and nocturia should be associated with other chronic tubulointerstitial nephropathy (including renal medullary cystic disease) ), renal tubular acidosis, diabetes insipidus, etc., such as medullary cyst disease, its performance is symmetry involved, often combined with significant decline in renal function, reflux nephropathy, radiology clearly confirmed ureteral involvement, and in childhood There is a history of reflux, kidney tumors, which occur on one side, and renal papillary necrosis is often a bilateral lesion, which can be distinguished by acid-fast bacilli culture.

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