Hello, as you have specified that his serum creatinine is in normal range and urea is slightly raised. Its not so much high as to get alarmed. Urea is produced as by product of nitrgen metabolism processin body. I would suggest you to watch on his protein intake. Try to maintain a 1gm/kg/day protein balance in his diet. If hes used to consume more non veg food, he should cut it down. Follow this advice for a few weeks and get a repeat serum urea report done and notice for the change. If its still high or same consult a docotr as you made need some further studies. I hope i have answered your query. If need more clarification you can ask me. Thank you