Diagnosis of kidney damage in periarteritis nodosa

Instrumental diagnostics of polyarteritis nodosa

• The most informative method for diagnosing kidney damage in polyarteritis nodosa is angiography.
  • When it is performed, multiple round saccular aneurysms of the intrarenal vessels are detected in almost 70% of patients. In addition to aneurysms, areas of thrombotic occlusion and stenosis of the vessels are determined. Aneurysms are located bilaterally, their number usually exceeds 10, the diameter varies from 1 to 12 mm. Patients with typical aneurysms on angiograms, as a rule, have more severe arterial hypertension, they have more pronounced weight loss and abdominal syndrome, HBsAg is detected more often.
  • Another pathognomonic angiographic sign is the lack of contrast in the distal segments of the intrarenal arteries, which creates a characteristic “burnt tree” picture.
• Angiography limits the renal dysfunction that is present in most patients with periarteritis nodosa, which can be aggravated by the administration of radiocontrast drugs. In this regard, ultrasound Dopplerography of the renal arteries has been used in recent years, but the diagnostic value of this noninvasive method of examination in comparison with angiography needs to be clarified.
• Renal biopsy is rarely performed on patients with polyarteritis nodosa, as it is associated with the risk of bleeding when the aneurysm is injured. Indications for the procedure may be limited to severe arterial hypertension.

Laboratory diagnostics of polyarteritis nodosa

Laboratory changes in polyarteritis nodosa are nonspecific. The most common findings are an increase in ESR, leukocytosis, and thrombocytosis. Anemia is usually observed in chronic renal failure or gastrointestinal bleeding. In patients with polyarteritis nodosa, dysproteinemia with an increase in the concentration of γ-globulins, rheumatoid and antinuclear factors, almost 50% of cases of antibodies to cardiolipin, and a decrease in the level of complement in the blood, which correlates with the activity of the disease, are detected in the blood. HBV infection markers are detected in more than 70% of patients. In the active phase of the disease, an increase in the level of circulating immune complexes is usually recorded.

Differential diagnosis of periarteritis nodosa

Diagnosis of polyarteritis nodosa is not difficult at the height of the disease, when there is a combination of kidney damage with high arterial hypertension with disorders of the gastrointestinal tract, heart, and peripheral nervous system. Difficulties in diagnosis are possible at early stages before the development of damage to internal organs and in the monosyndromic course of the disease. In the case of a polysyndromic nature of the disease in patients with fever, myalgia, and significant weight loss, it is necessary to exclude polyarteritis nodosa, the diagnosis of which can be confirmed morphologically by biopsy of the skin-muscle flap by detecting signs of necrotizing panvasculitis of medium and small vessels, however, due to the focal nature of the process, a positive result is noted in no more than 50% of patients.

Nodular polyarteritis with kidney damage must be differentiated from a number of diseases.

• Chronic glomerulonephritis of the hypertensive type, in contrast to nodular polyarteritis, is more benign, without signs of systemic damage, fever, or weight loss.
• Systemic lupus erythematosus affects mainly young women. Abdominal pain syndrome, severe polyneuropathy, coronary artery disease, and leukocytosis are not typical. Kidney damage is most often manifested by nephrotic syndrome or rapidly progressive glomerulonephritis. Malignant arterial hypertension is not typical for systemic lupus erythematosus. Detection of LE cells, antinuclear factor, and antibodies to DNA confirm the diagnosis of systemic lupus erythematosus.
• Subacute infective endocarditis is manifested by high fever, leukocytosis, and dysproteinemia. Severe arterial hypertension, arthritis, and severe myalgia with muscle atrophy are not characteristic of subacute infective endocarditis. EchoCG reveals vegetations on the heart valves and signs of heart defects. Repeated bacteriological blood tests are of decisive importance in the diagnosis of subacute infective endocarditis.
• Alcoholic disease may progress with damage to the peripheral nervous system, heart, pancreas (abdominal pain), kidneys (persistent hematuria); in most cases, arterial hypertension is noted. In such patients, anamnesis collection (the fact of alcohol abuse, the onset of the disease with an episode of jaundice due to acute alcoholic hepatitis) and examination (revealing "minor" signs of alcoholism - finger tremor, vegetative lability, Dupuytren's contractures) are of particular importance. Laboratory testing reveals a high concentration of IgA in the blood, characteristic of alcoholism
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