Hello & welcome to HCM forum
1) Your uncle is suffering from chronic kidney disease
(as blood urea & creatinine is raised) and most likely benign hypertrophy of prostate (as defined by you).
2) You have not mentioned that your uncle is passing urine himself or any urinary catheterization
has been applied. If he is passing urine himself then there is least chance of obstructive uropathy
as he is passing 2 liters urine in 24 hours.
3) There is high chances of CKD as serum potassium and Renal Function test are deranged and diabetes is also a major culprit disease for CKD world wide (2nd most common disease is hypertension)
4) You should consult Nephrologist
(as urea & creatinine, potassium are deranged) as well as urologist
(as he has prostatomegaly).
5) Fainting attacks may due to stroke or Uraemic encephalopathy.
Get well soon & wishing for rapid recovery
Dr. Mayank Bhargava