Blood urea nitrogen is not a reliable test for kidney function as it is influenced by diet, hydration, and salt intake.

“bun blood urea nitrogen is not a test of kidney function okay if you're eating more nitrogen sometimes b1 goes up bun can also go up if you're dehydrated if you're not eating enough salt bun is all over the place the un is not a good test of kidney function in someone that has kidney failure the u1 will rise but that doesn't mean that does not mean that a bun that is slightly higher than normal or at the high end of normal indicates anything wrong with your kidneys recheck it hydrate add more salt it changes a lot based on what you're eating bun is not a good measure of kidney function”