The normal value of urea nitrogen and creatinine ratio is between 12-20 to 1. Clinically, first, the urea nitrogen and creatinine ratio is often elevated due to high urea nitrogen level, which is often seen in patients with high protein diet and patients with gastrointestinal bleeding, as well as increased urea nitrogen absorption due to prerenal factors, such as dehydration, shock, reduced blood volume, or postrenal obstruction, resulting in increased urea nitrogen absorption. Secondly, if the ratio of urea nitrogen to creatinine decreases, it often indicates that the patient may have malnutrition, starvation, low protein diet, dialysis or after using diuretics, which may lead to a decrease in the ratio of urea nitrogen to creatinine.