However, if BUN and creatinine are both elevated significantly and the ratio is 20 is a sign of inadequate hydration. So, to summarize, the high BUN-Creatinine ratio, particularly if it is more than 20 and the person has a normal creatinine, usually indicates dehydration. Notice, in this case, the BUN/Creatinine ratio is not higher than 20 and BUN and creatinine have normalized. Now if the same person had about 1 liter of water to drink during that run, the laboratories would look something like this: BUN of 16 mg/dl and creatinine of 0.95 mg/dl. Notice, that the BUN/Creatinine ratio in this case is higher than 20 indicating dehydration. If we sampled his laboratories, his chemistry profile may look something like: BUN level of 28 mg/dl and creatinine of 1.1 mg/dl. Let’s take an example of dehydration below-Ī 70 kg individual who is 40 years old just ran 2 miles in the hot sun, and did not have anything to drink. In this regard, both BUN and creatinine are elevated modestly or proportionately, and the ratio hence is not necessarily higher than 20. Drinking enough fluids can improve the high BUN: Creatinine ratio.Ī high BUN/Creatinine ratio can also be due to an ongoing kidney problem. A high BUN: Creatinine ratio in this case indicates dehydration but the good news is that it is reversible.

When the body is in a negative state of fluid balance, the kidney function gets affected. What causes a high BUN: Creatinine ratio?Īmongst a few others, one major factor is dehydration. But since kidney function is determined to some extent by a person’s fluid intake, a dehydrated body can lead to a high BUN: creatinine ratio. Together, both BUN and creatinine are used to estimate the kidney function. There are relatively few things that can affect the creatinine level hence the majority of fluctuations can be attributed to a change in kidney function. Hence, it is commonly used as a kidney function test as most adults make the same amount of creatinine every day. The measurement of urea in the blood is done via Blood urea nitrogen test or simply referred to as BUN.Ĭreatinine, on the other hand, is a molecular protein produced by the muscle and is relatively freely filtered by the kidneys. As the peptide bond breakage creates nitrogenous waste products, ammonia is produced which is converted into a nontoxic waste called urea by the liver. These are then absorbed through the gut and are the building blocks for protein. Normally, when we eat protein, the peptide bond gets broken to yield amino acids. One of such biomarker sets is that of the BUN: Creatinine ratio. However, when you consider this objectively to define how much a person is dehydrated, some laboratory biomarkers can help. For the most part, dehydration is a clinical diagnosis, from signs and symptoms that signify loss of water and electrolytes from the body. One of the many incomplete tasks in the hydration space is using biomarkers to objectively identify dehydration. The BUN : Creatinine ratio: Understanding Biomarkers of Hydration and Kidney Function.

Bun creatinine normal range