The normal values of blood creatinine and urea nitrogen vary slightly depending on the testing methods used at different hospitals. The normal value of blood creatinine is between 80-110 μmol/L, while the normal value of urea nitrogen is between 2.8-7.5 mmol/L. There may also be a slight difference in the range of reference values for men and women, as men have a higher metabolic rate than women, so the upper limit of the reference value may be slightly higher. Blood creatinine and urea nitrogen are both indicators of kidney function. Generally, if there is an increase in creatinine and urea nitrogen at the same time, it often indicates the presence of renal insufficiency. If the urea nitrogen is elevated while the creatinine is normal, it may be caused by the patient eating too much protein. Therefore, if you have abnormal blood creatinine and urea nitrogen, you should go to the hospital for further examination and diagnosis.