Cystatin C 1.22 mg per liter is usually not required for treatment. The normal level of cystatin C is 0.6-2.5 mg per liter. Cystatin C is mainly used in clinic to rule out the presence of glomerular disease, diabetic nephropathy, etc. in patients. Cystatin C is a product of cystine metabolism in the body, and because it is not affected by diet or gender, it has some diagnostic significance in the early stage, and may be more sensitive than creatinine when it is high. When this index is low, there is no clinical diagnostic significance, when it is high, we need to exclude the existence of glomerular disease, diabetic nephropathy, renal malignant tumors, etc. Combined with the ultrasound found that the kidneys are shrunken, and there is protein in urine, we need to exclude the existence of glomerular disease, and if necessary, carry out nephron puncture biopsy. In the clinic found that this index is increased, consult the nephrology department of the regular hospital for reasonable diagnosis.