Urinary creatinine and blood creatinine have a certain correlation, both are waste products produced by the body’s metabolism, and both reflect the function of the kidneys. Urine creatinine and blood creatinine are both reflecting the creatinine content in the body, blood creatinine refers to the creatinine content in serum, urine creatinine refers to the creatinine content in urine, creatinine metabolism is through the glomerular filtration, if the glomerular filtration function is abnormal, then the general urine creatinine will be reduced, and the blood creatinine will be increased. However, there is no necessary correlation between the two values, and blood creatinine is relatively stable. If there is an increase in blood creatinine, it mostly suggests that the kidney function is abnormal, but there are also certain physiological reasons for the increase in blood creatinine, such as eating too much protein, strenuous exercise, etc. The urine creatinine is often affected by the body’s function. Urinary creatinine, on the other hand, is often affected by the body’s metabolic status, diet and so on. Detecting urinary creatinine alone is not significant for the determination of renal function, and needs to be combined with blood creatinine to jointly illustrate the glomerular filtration function. Patients with abnormal blood creatinine or urinary creatinine need to consult a doctor in time, do not take medication, so as not to delay the condition.