Primary small vessel vasculitis renal damage

　　Primary small vessel vasculitis renal damage is more common in middle-aged and elderly people, occurring frequently in autumn and winter seasons. Most patients have prodromal symptoms such as influenza-like or drug allergy, with renal arteritis as the main pathological change. Small vessel arteritis (small vessel vasculitis) can occur in various organs throughout the body, with the kidney being the most susceptible organ. There are many causes of small vessel vasculitis, with 70% of the causes being unknown and belonging to primary; 30% are secondary to various diseases, such as systemic lupus erythematosus, allergic purpura, rheumatoid arthritis, and hepatitis B virus infection, all of which are secondary. Vasculitis is common in the following diseases:

　　1. Polyarteritis nodosa:Including classic polyarteritis nodosa, allergic vasculitis, granuloma (Churg-Strauss syndrome), and overlap syndrome.

　　2. Allergic vasculitis:Including allergic purpura, serum sickness-like reaction, and vasculitis related to infection, tumor, and connective tissue disease.

　　3. Wegener's granulomatosis, giant cell arteritis:Including pulseless disease, cranial arteritis, etc.

　　4. Other vasculitis syndromes:Including lymphomatoid granulomatosis, Behçet's disease, and thromboangiitis obliterans, etc. The clinical classification is mainly based on the size of the involved vessels and the presence or absence of granuloma formation.

　　Primary small vessel vasculitis renal damage often presents with irregular fever, rash, joint pain, muscle pain, weight loss, abdominal pain, and gastrointestinal symptoms; the extent of lung and kidney involvement is consistent, and it may manifest as allergic asthma, hemoptysis, or difficult-to-control pulmonary infection. Some patients may have sinusitis, otitis media, and ocular manifestations (conjunctivitis, granuloma, keratitis, peripheritis, iridocyclitis, and choroiditis, etc.).

　　Primary small vessel vasculitis renal damage is more common in middle-aged and elderly people, and is more prevalent in autumn and winter. Most patients have prodromal symptoms such as common cold or drug allergy. They often have irregular fever, rash, joint pain, muscle pain, weight loss, abdominal pain, and gastrointestinal symptoms; the extent of lung and kidney involvement is consistent, and there is hematuria in the early stage of kidney involvement, about 1/3 presenting as gross hematuria. Most patients have proteinuria or nephrotic syndrome. Hypertension is uncommon or mild, and half of the patients present with rapidly progressive glomerulonephritis. With timely and effective treatment, some patients may recover their renal function completely. Fever is common during the active phase, and some patients may have mild anemia, edema of the eyelids or lower limbs, and some patients may have rashes or ocular manifestations, etc.

　　The etiology of primary small vessel vasculitis renal damage is unclear. Prevention mainly involves regular physical examinations, early detection, early diagnosis, and early treatment. It is important to rest on time, exercise more, and develop good living habits.

　　The main clinical examination methods for primary small vessel vasculitis renal damage include laboratory examination and imaging examination, as follows:

　　1. Laboratory examination

　　1. Urinalysis: There are varying degrees of proteinuria, hematuria, and casts. Most patients have anemia, increased blood leukocytes, and occasionally, an increase in eosinophils. The erythrocyte sedimentation rate is rapid in the acute phase, and the quantitative C-reactive protein exceeds the normal range. Gamma globulin is often increased.

　　2. Serum anti-neutrophil cytoplasmic antibody (ANCA): Most ANCA are positive, which is an important basis for diagnosing primary small vessel inflammation; ANCA can reflect the activity or recurrence of the lesion, and ANCA positivity can appear about 4 weeks before recurrence. Ccr often decreases to varying degrees, and blood urea nitrogen and creatinine levels increase.

　　3. Renal biopsy: Early renal biopsy can help diagnose the disease.

　　Second, Imaging Examinations

　　Chest X-ray examination often shows alveolar hemorrhage, lobular pneumonia, or localized cavitary necrotizing pneumonia; CT scan can detect sinus or orbital lesions; B-ultrasound examination shows normal or increased size of both kidneys.

　　The diet of patients with primary small vessel inflammatory renal damage should be hygienic, and it is not allowed to eat sour and rotten, enzyme-rotten, or unclean food left overnight to avoid gastrointestinal diseases and affect recovery. The diet should be mainly high-protein, high-nutrition, energy-rich semi-liquid and liquid food, and a small and frequent meals approach should be adopted to maintain the patient's nutritional and electrolyte balance.

　　Early diagnosis and treatment of primary small vessel inflammatory renal damage is the key to improving the prognosis. The principle of combined use of glucocorticoids and cytotoxic drugs should be adopted routinely, and standard hormone therapy plus CTX can be given, with the course lasting for more than 2 years.

　　For patients with progressive deterioration of acute renal function, standard hormone therapy plus CTX pulse therapy or methylprednisolone pulse therapy plus CTX pulse therapy should be given as soon as possible under dialysis. Plasma exchange therapy also has certain efficacy, especially for pulmonary hemorrhage, which is certain and rapid. If accompanied by severe hypercapnia and refractory heart failure, emergency dialysis should be performed to help them through the dangerous period, creating conditions for drug treatment and gaining time.

　　General treatment includes rest, diet, diuresis, antihypertension, anticoagulation, and prevention and treatment of various complications, and should refer to the treatment of primary glomerulonephritis according to the patient's condition. Treatment with high-dose immunoglobulin and monoclonal anti-T cell antibody may have certain efficacy. End-stage renal failure patients should be treated according to chronic renal failure.