My father age 63, weight 53.he tested creatitine,blood urea and pottosaium 3weeks back.it is 1.1, 35, 6 and after 3weeks he again tested it is 1.2, 94, 5.4. why there is sudden increase in blood urea,my father is diabetic and heart patient.He is under medical management and using medicines for that and doctor said to take only 1litre per day.what further tests needed and y sudden raise in urea what is the reason.