Creatinine is a metabolite in the body, mainly produced by muscle metabolism and subsequently excreted in the urine through glomerular filtration. The normal value of urine creatinine (enzymatic method) is usually 40-130mg/dL, and the normal value of blood creatinine is 44-133μmol/L. Since blood creatinine is more meaningful to measure kidney function, high creatinine usually refers to high blood creatinine, and generally blood creatinine >133μmol/L is considered high, but due to different examination equipment in each hospital, the reference standard may differ to some extent, so it is recommended to consult with the doctor in person. Creatinine in the body mainly consists of exogenous creatinine and endogenous creatinine. Exogenous creatinine is produced by metabolizing fat consumed through food in the body, and endogenous creatinine is a product produced by muscle tissue in the body. Elevated creatinine may be related to the kidney. In the absence of significant changes in exogenous creatinine, blood creatinine concentration is mainly influenced by the filtration function of the glomerulus, and damage to the renal parenchyma can affect the filtration function, thus leading to an increase in blood creatinine concentration. For example, if the glomerular filtration function is damaged, the blood creatinine concentration can be increased, which is common in urinary stones, chronic glomerulonephritis, nephrotic syndrome, etc. It can be accompanied by hematuria, proteinuria, or symptoms such as frequent and painful urination. If the blood creatinine concentration is >178 μmol/L, it can be seen in the decompensated stage of renal failure. However, there are also cases in which creatinine is elevated despite good health, such as athletes with high muscle content and therefore high relative creatinine levels, and heavy exercise may also cause creatinine to rise. The creatinine elevation caused by these conditions is usually mild, but tests such as urine routine are needed to clarify the presence of kidney disease. Normal creatinine does not mean that there is no kidney dysfunction. Older women have lower creatinine levels, and blood creatinine is lower in the middle and late stages of pregnancy compared to the pre-pregnancy period, so this special group of people with high creatinine may have kidney problems even if they are in the normal range, and they need to undergo urine routine and other tests to clarify whether there is kidney disease. Therefore, you cannot judge whether there is a problem in your body based on creatinine alone, but you also need to make a comprehensive judgment based on other tests and symptoms. In case of high creatinine, it is necessary to determine whether there is a disease through blood routine, urine routine, kidney ultrasound or CT and other examinations.