Bun Creatine Ratio Calculator

The BUN creatinine ratio calculator calculates a patient’s blood urea nitrogen to creatinine ratio. Learn how to compute the BUN creatinine ratio, why we test it, and what it means to have a high or low BUN creatinine ratio.

Because blood urea nitrogen and creatinine are both metabolites, the body produces them regularly. The distinction is in how they act in the nephron, the kidney’s functional unit. We normally filtered creatinine before being secreted directly into the tubule lumen. Because BUN is filtered and subsequently reabsorbed into the blood, we have more BUN than creatinine in our blood.

BUN Creatinine Ratio Calculator – How To Calculate BUN Creatinine Ratio?

The blood urea nitrogen (BUN) test is useful in evaluating whether you have a renal or nutritional condition. However, a test called BUN creatinine ratio is used to further the diagnosis and try to pinpoint the exact cause of renal failure.

Blood urea nitrogen and creatinine are used, both of which are tested in serum. The levels of BUN and creatinine depend on kidney function, but when they’re combined, they can reveal the location of the damage, such as whether it’s an intrinsic renal or prerenal issue. You’re OK to go if you can compute the BUN creatinine ratio.

This parameter is a ratio, as its name implies:

BUN creatinine ratio = blood urea nitrogen (mg/dL) / serum creatinine (mg/dL)

The units in the formula are precise, but you can choose the ones that are most suitable for you in our calculator, and it will automatically recalculate them. Simply enter the known values, and your result will appear.

Bun Creatine Ratio Calculator- High and Low Value Of Bun Cr Ratio

What does a high or low BUN creatinine ratio signify in terms of a patient’s health? It’s easy to answer: A BUN/creatinine ratio of greater than 20 shows a prerenal source, whereas a ratio of less than 10 shows an intrinsic renal cause.

The table below offers a list of potential explanations for both outcomes, which should all be put into consideration:

BUN/creatinine >20BUN/creatinine <10
dehydrationacute tubular necrosis
hypovolemialiver disease
shock, heart attack, severe burnsmalnutrition
congestive heart failurepregnancy
very high protein intakeSIADH (syndrome of inappropriate antidiuretic hormone)
gastrointestinal bleedingrhabdomyolysis
advanced agecorticosteroids administration or Cushing’s syndrome

Bun vs creatine

We frequently associated the high BUN creatinine ratio with a low glomerular filtration rate. Because of the low flow, we filter weakly both metabolites, but urea (which contains urea nitrogen) ‘leaks out’ back into the blood, increasing the ratio. If the ratio is low, it suggests that compounds that have already passed through the kidney have not been filtered.

One of the metrics used to evaluate kidneys is the BUN creatinine ratio. We can compute fractional excretions – such as salt or urea – by measuring creatinine in urine. Trans-tubular potassium gradient is more than useful if potassium is a concern. We can estimate GFR using the creatinine clearance parameter if all we have is serum creatinine.

Bun Levels and Definition

BUN (short of blood urea nitrogen) is a blood test that determines the amount of urea nitrogen in the body. We produce urea in the liver as a waste product of protein breakdown. We used it as a criterion to assess a person’s nutritional status and the kidney and liver’s health.

Blood urea nitrogen levels should be between 8 and 20 mg/dL (2.9 and 7.1 mmol/L).

  • A protein-rich diet (e.g., a high meat intake), kidney malfunction, congestive heart failure, gastrointestinal bleeding, or situations of sped up catabolism can all generate high readings (>20 mg/dL) (massive burns or cancer)
  • Malnutrition, liver illness, and SIADH can all cause low readings (less than 8 mg/dL) (syndrome of inappropriate antidiuretic hormone)

You must also know about these questions, “Does Creatine Cause Hair Loss“?

Creatine Levels and Definition

Creatinine is a byproduct of the breakdown of creatinine phosphate in muscles. The amount of muscle mass in the body determines creatinine levels in a normal state, which is why males typically have greater creatinine levels than women. It also reflects how organs like the kidneys and liver are doing.

  • Serum creatinine levels should be between 0.7 and 1.3 mg/dL (62 and 115 mol/L).
  • Kidney illness or a large percentage of muscle mass to total body weight might induce high levels (>1.3 mg/dL).
  • Malnutrition, muscular atrophy, or severe liver disease can also generate low readings (0.7 mg/dL).

Urea Blood Levels and Creatine

Using creatinine or urea measurements to assess renal function is justified because their plasma/serum levels both reflect glomerular filtration rate (GFR), which is the parameter that the clinician uses to define kidney function. Kidney disease, regardless of its cause, is linked to a reduction in GFR, and we inversely related the severity of kidney disease to GFR.

A normal GFR (125 mL/min) shows that the kidneys are in good working order. Urinary excretion of urea and creatinine decreases as GFR (kidney function) decreases, while blood concentrations of both rise.

The blood concentration of an endogenously generated substance must have the following features to reflect GFR in health and disease:

The kidneys can only eliminate it.

  • The glomerulus must be able to filter blood freely.
  • It cannot be reabsorbed from the filtrate into the bloodstream or secreted from the bloodstream into the filtrate by the renal tubule cells (i.e. we filter all that at the glomerulus appears in urine, and all that is in urine is because of glomerular filtration)
  • Diet and/or changes in endogenous production rate must have no effect on the substance’s blood levels (i.e. a change in GFR affects it)

Both plasma urea and plasma creatinine concentration are imperfect indicators of GFR since neither analyte completely meets the above criteria (see Table I below) and both have insufficient sensitivity to detect even minor changes in GFR.


Our BUN creatinine ratio calculator can assist you in determining the ratio of blood protein in the urine to creatinine. The blood urea nitrogen (BUN) test is always done to see if you have a renal or nutritional problem. A test called BUN creatinine ratio is used to help with the diagnosis and to establish the exact cause of renal failure.


What does having a high BUN creatinine mean?

A high BUN value can result from a high-protein diet, Addison’s disease, tissue injury (such as from severe burns), or gastrointestinal hemorrhage. High BUN-to-creatinine ratios are associated with acute renal failure, which can be caused by shock or severe dehydration.

What is the BUN creatine ratio?

The BUN Creatinine Ratio is one of the most commonly measured kidney function markers, especially when determining the specific etiology of renal failure.
Blood urea nitrogen (BUN) and creatinine are two metabolites that the body produces regularly. However, whereas BUN is filtered in the nephrons of the kidney before being reabsorbed into the blood, we filtered creatinine before being secreted in the lumen. As a result, a healthy person’s blood contains more BUN than creatinine. BUN levels may drop if substantial liver damage or disease prevents the synthesis of urea.

What is the BUN to creatinine ratio in a healthy person?

Between 10-to-1 and 20-to-1 is the optimal BUN-to-creatinine ratio. If your ratio is above this level, you may develop congestive heart failure, dehydration, or gastrointestinal bleeding.

What level of creatinine is excessive?

High creatinine levels can cause kidney injury or dehydration. A creatinine level of over 1.3 is high (depending on age, race, gender, and body size). A variety of factors might cause creatinine levels that are greater than usual.

What is the definition of a high BUN level?

BUN levels should be between 7 and 21 milligrams per deciliter (mg/dL). This level may not be useful in determining your kidney health until it is greater than 60 mg/dL.

Is it true that drinking water reduces the amount of protein found in the urine?

Unless you’re dehydrated, drinking water won’t help you get rid of the protein in your urine. Drinking water will dilute your urine (dilute the amount of protein and other substances in your urine), but it will not stop your kidneys from leaking protein.

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