IgA nephropathy is a group of chronic glomerular diseases with the same immunopathological features caused by multiple etiologies. Clinically, about 40%￣45% of patients present with carnal or microscopic hematuria, 35%￣40% present with microscopic hematuria with proteinuria, and the rest present with nephrotic syndrome and renal failure. IgA nephropathy nephropathy is a common glomerular disease worldwide, and the prevalence of IgA nephropathy varies greatly from continent to continent, from country to country, or from region to region in a country. The following is an introduction to the examination of the altered glomerular pathological patterns. 1, urinary β2-microglobulin clearance Urinary β2-microglobulin clearance is an auxiliary test used to determine whether glomerular function is normal. β2-microglobulin is produced from lymphocytes and is rarely present in urine, because of its small molecular weight, it can freely pass through the glomerular filtration membrane. The increase of β2-microglobulin in urine should be considered as either an increase in synthesis or a decrease in proximal tubular reabsorption. If there is no disease causing increased synthesis, the increase may reflect reduced proximal tubular reabsorption. Acute tubular injury or necrosis, chronic interstitial nephritis and chronic renal failure can make urinary β2-microglobulin significantly higher. 2.Glomerular filtration rate The amount of filtrate produced by the two kidneys per unit of time is called glomerular filtration rate, which is about 125ml/min in normal adults. The ratio of glomerular filtration rate to renal plasma flow is called filtration fraction. Renal plasma flow is about 660 ml per minute, so the filtration fraction is 125/660×100%≈19%. This result indicates that about 1/5 of the plasma flowing through the kidney is filtered by the glomerulus into the capsule to produce primary urine. Glomerular filtration rate and filtration fraction are indicators of renal function. 3, effusion lysozyme Lysozyme is a component of the normal body immune defense mechanism and has the effect of lysing the bacterial cell wall. In the human body, it exists in neutrophils, monocytes and macrophages; it also exists in mucosal secretion, and becomes one of the body surface defense factors. Lysozyme is not present in normal human urine. The value of lysozyme activity in the serum or body fluids of patients with certain diseases varies significantly, so the determination of lysozyme activity is receiving increasing clinical attention.