The examination cost of urea nitrogen and creatinine may vary according to different hospitals and different regions, and the approximate cost ranges from 20-30 dollars. Urea nitrogen and creatinine is an indicator of kidney function, and creatinine and urea nitrogen will be elevated when kidney function is not good. However, normal creatinine and urea nitrogen do not necessarily mean that the kidneys are normal, because creatinine and urea nitrogen will increase when the glomerular filtration rate drops below 50ml/min. Before that, when the glomerular filtration rate decreases, the creatinine and urea nitrogen may remain in the normal range because the kidney’s compensatory function is stronger. Therefore, in addition to creatinine and urea nitrogen, it is also necessary to check cystatin C, urine routine and other related tests to determine whether there is kidney damage in advance.