Chronic pyelonephritis

Bacterial chronic pyelonephritis is a term used to describe the effects of a long-standing infection on the kidney. This may be either an active process with persistent infection or the consequences of a previous kidney infection. These two conditions, active or inactive (healed) chronic pyelonephritis, differ in the presence or absence of morphological signs of infection, leukocyturia, and bacteriuria. This distinction is important because treatment is not indicated for an inactive process.

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Causes chronic pyelonephritis

Bacterial pyelonephritis almost invariably occurs in patients with complicated urinary tract infection or diabetes mellitus. The process is highly variable, depending on the state of the host organism and the presence of structural or functional changes in the urinary tract. The process can persist for many years if the damage is not corrected. Long-term infection leads to weakening of the organism and anemia. There is a high probability of complications: renal amyloidosis, arterial hypertension and terminal renal failure.

Few diseases generate as much debate and controversy as chronic pyelonephritis. The word "chronic" conjures up a vision of a persistent, smoldering process that inexorably leads to kidney destruction if its course is not interrupted, i.e. the disease must end in nephrosclerosis and renal shrinkage. In fact, most patients with urinary tract infection, even with frequent recurrent attacks, rarely develop late-stage renal failure. After recurrent infections in the absence of organic or functional changes in the urinary tract, as after the primary acute form of the disease (at least in adults), nephrosclerosis and chronic renal failure do not occur. They most often occur in the context of diabetes mellitus, urolithiasis, analgesic nephropathy, or urinary tract obstruction. This is why it is so important to accurately define the terminology and risk factors.

Another source of confusion is the tendency to interpret focal renal scars and malformed calyces seen on excretory urograms as "chronic pyelonephritis" rather than as old healed pyelonephritic scars or as a result of reflux nephropathy. It is known that scars acquired after the acute form of the disease and vesicoureteral reflux in childhood are the main source of findings in adults. The key role of vesicoureteral reflux in the development of renal scars is based on the work of several researchers.

Chronic pyelonephritis is the result of the combined action of infection and impaired urodynamics due to organic or functional changes in the urinary tract.

In children, nephrosclerosis often develops against the background of vesicoureteral reflux (reflux nephropathy). An immature developing kidney is more easily damaged by a bacterial infection than a formed organ. In general, the younger the child, the higher the risk of irreversible damage to the renal parenchyma. In children over 4 years of age with vesicoureteral reflux, new areas of sclerosis rarely form, although old ones can increase. In addition to the child's age, the severity of reflux nephropathy directly depends on the severity of vesicoureteral reflux.

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Symptoms chronic pyelonephritis

Symptoms of chronic pyelonephritis most often manifest as nonspecific signs of infection, including fever, anemia, and azotemia. Chronic pyelonephritis may be asymptomatic, or there may be recurrent episodes of the acute form of the disease or manifestations.

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Complications and consequences

Uncontrolled infection in the kidneys may spread to surrounding tissues and form a perinephric abscess. The extent of the infection is difficult to determine without radiological studies. Perinephric abscess should be suspected in the presence of persistent flank pain, fever, leukocytosis, despite ongoing antibacterial chemotherapy. Surgical drainage is usually required. The patient may develop urosepsis, often accompanied by bacteremia and endotoxemia.

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Diagnostics chronic pyelonephritis

Laboratory diagnostics of chronic pyelonephritis

Laboratory findings are similar to those seen in the acute form of the disease. Patients with long-standing infection may have normocellular, normochromic anemia with normal iron-binding protein and ferritin.

C-reactive protein is usually elevated in patients with active infection. In patients with severe bilateral infection, serum urea and creatinine are elevated. The concentrating ability of the kidneys is markedly reduced, but excessive proteinuria is rare except in end-stage renal failure.

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Instrumental diagnostics of chronic pyelonephritis

Radiologic findings consist mainly of anatomical changes related to underlying structural changes and sequelae of the infectious process. The renal cortex may be wrinkled due to multiple, irregular cortical scars with focal folding of the renal pelvis. These changes may be confused with those occurring in vesicoureteral reflux and renal arterial hypertension. CT may reveal an abscess that may contain gas (emphysematous chronic pyelonephritis) or resemble a tumor (xanthogranulomatous form of the disease).

Differential diagnosis

The clinical diagnosis of active, bacterial chronic pyelonephritis is based on the history, clinical, laboratory, and radiological data. In patients with recurrent, complicated infection or with diabetes mellitus, in whom the symptoms of the disease are associated with bacteriuria and pyuria, the diagnosis is not difficult to establish. The main problem is to distinguish residual lesions of the previous infectious process, which are no longer active, from other diseases with similar radiological data.

Conditions that can mimic chronic pyelonephritis are listed below:

Clinical:

• kidney stones and ureteral obstruction;
• kidney tumor;
• subphrenic and lumbar abscess;
• fever of unknown etiology.

Radiological:

• reflux nephropathy;
• arterial hypertension of renal genesis;
• renal artery stenosis:
• diabetic nephropathy;
• interstitial nephritis;
• analgesic nephritis.

Treatment chronic pyelonephritis

Treatment of chronic pyelonephritis is carried out using surgical and antibacterial methods of treatment.

If the process is untreated or chronic pyelonephritis is treated inadequately, the process can persist for many years and be complicated by general weakness, anemia and gradually progress to renal amyloidosis, arterial hypertension and terminal renal failure.