High urea nitrogen in children may be caused by improper diet, kidney disease and so on. 1. Improper diet: If you have recently eaten high protein food, such as fish, eggs, lean meat, soy products, etc., it will lead to high urea nitrogen. No special treatment is needed. Adjusting the diet and avoiding eating too much high protein food can usually return to normal. 2. Kidney disease: renal dysfunction, such as nephritis, renal tumor, renal insufficiency and other diseases, will lead to urea nitrogen can not be well discharged from the body, the patient usually have edema, vomiting, diarrhea and other abnormal symptoms. Children with high urea nitrogen can not be reduced, it is recommended to go to the regular hospital as soon as possible, improve the relevant examination, confirm the cause of the targeted treatment.