1.What is rapidly progressive glomerulonephritis? Here, acute means rapid progression, in other words, acute glomerulonephritis (hereinafter referred to as RPGN) refers to a type of glomerulonephritis in which the disease progresses rapidly after the onset of the disease, resulting in the rapid loss of renal function in a short period of time (usually within a few weeks or months), and the patient enters into the uremic stage. Because more than 50% of the glomeruli of these patients are found to have large crescent formation on renal biopsy, RPGN is also known as crescentic nephritis. 2.What are the clinical characteristics of acute glomerulonephritis? (1) Rapid progression of the disease, often accompanied by oliguria, anuria; the patient will find facial, bilateral lower extremity edema, elevated blood pressure; sometimes can be excreted naked eye hematuria. If it is type I, some patients may have hemoptysis or even dyspnea due to diffuse alveolar hemorrhage. (2) Urinalysis suggests proteinuria and hematuria; blood biochemistry test suggests that blood creatinine and urea are significantly elevated, suggesting progressive renal decompensation. Blood routine can see mild and moderate anemia manifestation, sometimes platelets and leukocytes are seen to be increased. In addition, according to different types of RPGN, there may be positive anti-glomerular basement membrane (GBM) antibody and anti-neutrophil cytoplasmic antibody (ANCA). (3) Ultrasound and other imaging tests show that the kidneys are not small or even enlarged. (4) Renal biopsy showed that more than 50% of glomeruli had large crescent formation. Immunofluorescence examination varies with different types of RPGN. 3.What are the types of acute glomerulonephritis? According to clinical, immunologic and pathologic conditions, there are 3 types of RPGN: type I (anti-glomerular basement membrane type), type II (immune complex type), and type III (no immune complex). type I has two peaks of incidence, which are in young adults (20-40 years old) and the elderly (60-80 years old). Type III is often associated with anti-neutrophil cytoplasmic antibodies (ANCA) positivity. Some people refer to those with both type I and type III characteristics as type RPGN. 4. What are the causes and pathogenesis of acute glomerulonephritis? There are several causes of this disease, including: (1) Anti-glomerular basement membrane antibody-mediated glomerulonephritis; anti-glomerular basement membrane antibody combines with glomerular basement membrane antigen to activate complement and cause disease. (2) Immune complex-mediated glomerulonephritis: e.g., secondary to infections (staphylococcal and streptococcal post-infectious glomerulonephritis, visceral abscess/sepsis, hepatitis B virus infection); and secondary to a variety of collagen-vascular disorders (e.g., systemic lupus erythematosus, purpura allergic, cryoglobulinemic glomerulonephritis, IgA nephropathy). As well as a variety of primary renal diseases, such as membranoproliferative glomerulonephritis, fibrillar glomerulopathy. It is caused by the deposition of circulating immune complexes in the glomerulus or the formation of in situ immune complexes, which activate the complement. (3) ANCN-associated glomerulonephritis: including microscopic polyangiitis, Wegener’s granulomatosis, allergic granulomatous vasculitis. 5.How to treat acute glomerulonephritis? (1) General treatment: bed rest, low-salt, low-protein diet, i.e., 0.6-0.8g of protein per kilogram of body weight per day; hydration as appropriate, and attention to the correction of metabolic acidosis and prevention of hyperkalemia. (2) Corticosteroid shock therapy methylprednisolone 0.5-1.0g/day sedation, 3 consecutive days; later changed to oral prednisone, the dose of 1mg per kilogram of body weight per day, 3-6 months after the decreasing. Cyclophosphamide should be applied at the same time, either orally or intravenously. type II still needs to pay attention to the treatment of underlying diseases. (3) Plasma exchange: The aim of this therapy is to rapidly remove pathogenic antigens, antibodies and their immune complexes, as well as inflammatory mediators from the blood circulation. The patient’s plasma can be removed by traditional plasma exchange or modern double filtration devices, with 2-4 liters of plasma each time, once a day or every other day, and then replenished with an equal amount of fresh plasma or 5% human albumin solution. Plasma exchange therapy requires the concomitant use of corticosteroids and cytotoxic immunosuppressants, otherwise the disease will rebound. Plasma exchange therapy is more effective for patients with type I and III, especially when combined with pulmonary hemorrhage, plasma exchange can rapidly relieve the condition. It is worth noting that plasma exchange is expensive and has the risk of infectious diseases. (4) Dialysis and renal transplantation: When the condition is serious and the symptoms of uremia are obvious, early hemodialysis is often needed; if the glomerular filtration function can no longer be restored, long-term dialysis treatment is needed. Patients with anti-GBM and ANCA-related RPGN should preferably undergo dialysis treatment for 6 months to 1 year, and then undergo renal transplantation after the serum titer decreases and turns negative. 6. What is the prognosis of acute progressive glomerulonephritis? The prognosis of type I RPGN is poor, and most patients need renal replacement therapy; type II and III RPGN have relatively good prognosis, and can be taken off dialysis with timely treatment. The prognosis of patients with oliguria, anuria, blood creatinine more than 600umol/L, and 85% of glomeruli with large crescent formation in renal biopsy is relatively poor.