Although you have not mentioned your brother's age,I assume that he is more than 15 years.If that is the case then kidneys have alredy shrunk & urea &
creatinine may not be completely recoverable.
There are some dugs which may help you to reduce urea & creatinine but before that you should reduce salt & protein intake from your diet.
You may start Cap Cudo Forte 1OD & Tab Sodabicarb for this