What are the causes for elevated bun not kidney?
 cardiac decompensation, water depletion due to decreased intake and excessive loss, increased protein catabolism, and high protein diet, acute glomerulonephritis, chronic nephritis, polycystic kidney disease, nephrosclerosis, and tubular necrosis, all types of obstruction of the urinary tract, such as stones, enlarged prostate gland, tumors are the causes of elevated bun not kidney. 