Endogenous creatinine clearance is age-related. Endogenous creatinine clearance is useful in determining renal function to a certain extent and can reflect the degree of renal parenchymal damage. The volume of renal parenchyma shrinks with age, and endogenous creatinine clearance decreases accordingly. Endogenous creatinine clearance is the amount of creatinine produced by the metabolism of substances in the body, and is numerically close to the glomerular filtration rate. Endogenous creatinine clearance is affected by a number of factors, including the presence of creatinine in meat or the production of creatinine from strenuous muscle exercise, both of which can increase the amount of creatinine and cause bias in test results. Endogenous creatinine clearance is also affected by renal function, which can be impaired causing a decrease in endogenous creatinine clearance. Abnormal endogenous creatinine clearance requires prompt medical attention and standardized diagnosis and treatment under the guidance of professional doctors.