IgA nephropathy is an immune complex glomerulonephritis characterized by IgA deposition in the glomerular thylakoid region, which is the most common primary glomerular disease worldwide and the main type of chronic kidney disease in China, accounting for about 40% of primary glomerular diseases in China. In the past, IgA nephropathy was considered to be a disease with good prognosis, but it is now clear that IgA nephropathy is a progressive disease, with about 20% of patients progressing to chronic renal failure every 10 years after the onset, and IgA nephropathy is still the first primary cause of chronic maintenance hemodialysis in China. Therefore, importance should be attached to the early diagnosis and treatment of IgA nephropathy patients to delay the deterioration of renal function and reduce the occurrence of uremia in IgA nephropathy patients as much as possible. Diagnosis of IgA nephropathy IgA nephropathy mainly manifests clinically as hematuria and varying degrees of proteinuria, which is not essentially different from the clinical manifestations of other nephritis, therefore, it is difficult to make an exact diagnosis based on clinical manifestations alone.The diagnosis of IgA nephropathy must rely on the pathological diagnosis of renal biopsy. 1, how to choose a kidney biopsy case A very important issue in the pathological diagnosis of IgA nephropathy is the selection of kidney biopsy cases. Most nephrologists in Europe and the United States advocate that renal biopsy should be performed only in patients with persistent urine protein greater than 1 g/24 h. After summarizing and analyzing the clinicopathological data of more than 1000 cases of IgA nephropathy, we found that if we follow this criterion, we may miss some patients who need active treatment. This is because there are many patients with urine protein around 0.5 g/24 h who already have moderate (Lee’s classification grade III) pathological damage. Therefore, we advocate that in hospitals with more mature renal biopsy techniques, renal biopsy can be considered as long as persistent urine protein >0.5 g/24 h is accompanied by microscopic hematuria. So that early diagnosis, early treatment and maintenance of normal and stable renal function can be achieved. Although the clinical manifestation of IgA nephropathy lacks specificity, recurrent carnal hematuria after cold or tonsillitis episodes and increased serum IgA/C3 ratio (>3) should highly suspect IgA nephropathy. Treatment of IgA nephropathy The pathogenesis of IgA nephropathy is complex and involves many factors, and so far, there are no specific measures to treat IgA nephropathy. Since the prognosis of IgA nephropathy is mainly related to hypertension, massive proteinuria, impaired renal function, glomerulosclerosis, interstitial fibrosis and small renal artery sclerosis, the treatment of IgA nephropathy should be treated differently according to the presence or absence of these indicators and the degree of severity, and individualized graded treatment should be adopted. 1. For patients who develop meatus hematuria or abnormal urinalysis aggravation after tonsillar infection, actively control the infection and perform tonsil removal as early as possible. Retrospective studies have shown that tonsil removal is effective for mild to moderate IgA nephropathy and can reduce the incidence of proteinuria, hematuria and end-stage renal failure. 2. For patients with normal blood pressure, normal renal function and urinary protein <1 g/24 h, most foreign scholars believe that no special treatment is needed and only regular review is required. However, we found that these patients should be combined with the pathological manifestation of renal biopsy and the corresponding treatment plan should be formulated to actively treat the patients, which is conducive to their complete remission. 3. For patients with urine protein >1 g/24 h, ACEI or (and) ARB are preferred, and strive to reduce urine protein to less than 0.5 g/24 h. If adequate ACEI and ARB are used, blood pressure has been reduced to 125/75 mmHg and urine protein is still >1 g/24 h in patients with normal renal function, additional glucocorticoid therapy is appropriate. The application of hormones and other immunosuppressive agents should consider renal biopsy pathological changes in addition to the amount of urine protein. Significant inflammatory cell infiltration, cell proliferation, and especially cell crescent formation are indications for the application of hormones and other immunosuppressive agents. For patients with IgA nephropathy combined with microscopic lesion nephrotic syndrome, they are treated as microscopic lesion nephrotic syndrome. 4. For patients with IgA nephropathy combined with hypertension, strive to reduce blood pressure to below 130/80 mmHg; if urine protein >1.0 g/24 h, try to reduce blood pressure to 125/75 mmHg. commonly used antihypertensive drugs include ACEI, ARB, long-acting calcium antagonists, diuretics and beta-blockers and alpha-blockers.