What causes an elevated bun/creatinine ratio on your lab results?

Dehydration. Is most common cause of high BUN with normal creatinine (therefore high ratio). Other causes can be high protein load in the diet, muscle injury or muscle breakdown (bun is formed by the breakdown of proteins). Whether to worry depends on how high the BUN is, and the circumstances when the test was drawn. Talk to the doctor who ordered the test for personalized interpretation.