Creatinine is considered abnormal as long as it is not in the normal range. Creatinine is divided into blood creatinine and urine creatinine. When the kidneys are damaged, the glomerular filtration rate decreases, and when it decreases to a certain level, the creatinine concentration rises, so creatinine can detect glomerular filtration function. The normal value of creatinine may have different standards in different hospitals, and the normal value on the hospital checklist needs to be taken as the standard.1. The normal value of blood creatinine reference range: 18-62umol/L for children; 53-106μmol/L for adult males; 44-97μmol/L for adult females. increased blood creatinine is seen in acute and chronic glomerulonephritis, uremia, etc. When the kidney is stimulated by inflammation, it leads to Immune complex deposition in the glomerulus, or damage to glomerular cells, affecting glomerular filtration function and leading to high blood creatinine; 2. Normal reference range for urinary creatinine: 71-195umol/kg/24h urine in children, 7.1-17.1mmol/24h urine in adult men, 5.3-15.9mmol/24h urine in adult women. High urinary creatinine is seen with heavy exercise, excessive creatinine intake, or endocrine and metabolic system diseases, such as diabetes and hypothyroidism, etc. Abnormal hormone metabolism in the body can indirectly affect kidney function, such as diabetes combined with nephropathy. Blood creatinine can be combined with urine creatinine to determine renal function, for example, both can be used to calculate endogenous creatinine clearance, assess whether renal function is normal and the degree of impairment, and guide clinical treatment.