Urea Creatinine Ratio

The urea creatinine ratio is an indicator of how well the kidney’s functioning. When your kidneys do not work properly, it doesn’t filter out some of the wastes and toxins in the body. One of the thing it filters out is creatinine and another is urea nitrogen. These are both waste products of broken down foods and proteins. In people with kidney failure, you will not have much urea or creatinine in your urine, but higher levels in your blood.

Significance of Urea Creatinine Ratio

The urea creatinine ratio will measure how much urea is in your blood as well as the ratio between urea and creatinine. When your body breaks down proteins, the liver makes urea and it is excreted from the kidneys. The doctor may not always use this test as an indication of kidney failure, as it can also tell the doctor if your body is dehydrated or low on fluids. Here are all the reasons this test is done:

  • Severe dehydration
  • To check for normal or abnormal kidney function
  • Making sure those with kidney disease are not going into kidney failure
  • Check the kidneys on medications that are toxic to the kidneys

Test Preparation

Before having creatinine levels checked, it is important to follow a few guidelines:

  1. Avoid heavy exercise for at least 48 hours prior to the test.
  2. Drink plenty of fluids the day before and during a 24 hour urine collection. Avoid tea and coffee that will make you urinate more and could dilute the urine.
  3. Avoid eating over 8 ounces of proteins in any meal at least 24 hours prior to the test and during the test.

The day of the test, the lab will draw some blood to get a creatinine level. Then you will be given a urine container for a 24 hour urine test. The results between the blood urea nitrogen (BUN) and urine creatinine will determine the ratio.  

Urea Creatinine Ratio Ranges

The test results for urea creatinine ratio mean different things depending on if they are high or low. The ranges help doctors see if there is an issue with the kidneys, dehydration, or a urinary tract obstruction.  

Here’s the guideline from webmd:

Blood Urea Nitrogen (BUN) Value


10–20 milligrams per deciliter (mg/dL) or 3.6–7.1millimoles per liter (mmol/L)


5–18 mg/dL

Creatinine Value


0.6 - 1.2(mg/dL) in males and 0.5 to 1.1 (mg/dL) in females

BUN-to-Creatinine Ratio 


6–25 with 15.5 being the best value

High Urea Creatinine Ratio

  • Dehydration – Dehydration can slow the blood flow to the kidneys and raise the Urea Creatinine Ratio. It can appear as pre-renal failure, but usually subsides with either intravenous or oral fluids.
  • Injury to the kidney – An injury to the kidney due to trauma can cause a temporary elevated creatinine or urea creatinine ratio.
  • Disease outside the kidney – Diseases likecongestive heart failure, high blood pressure, and diabetes can cause an elevated urea creatinine ratio. They slowly damage the kidney and can cause them to fail, so doctors will periodically monitor these levels over the course of the disease.
  • Medications – Medications that can affect the urea creatinine ratio are diuretics, antifungal medications, cephalosporin antibiotics, rifampin, and methyldopa. Some of these medications can damage the kidneys so your doctor will monitor you closely while you are taking them.
  • High protein diet – If you are healthy, a high protein diet may affect and raise your urea creatinine ratio and it is usually nothing to worry about. If you have kidney disease, high protein diets only further stress the kidney and should be avoided. Many body builders on high protein diets experience changes in this lab and that is to be expected, but generally not dangerous.
  • Addison’s disease – This disease of the adrenal glands may elevate the test, but it is only one marker of Addison’s disease.
  • Gastrointestinal bleeding – When there is bleeding in the digestive tract the body digests the blood. The byproducts of digesting blood can raise the urea creatinine ratio. This test has helped doctors distinguish between upper and lower digestive tract bleeding.
  • Burns/Tissue damage – In severe burns, an elevated level is the product of muscle tissue being broken down and processed by the body.
  • Sudden acute kidney failure – This is usually secondary to life-threatening illness likeshock, septic infection, and severe blood loss. The blood flow to the kidneys is too low for them to work properly and they begin to shut down. This test can tell the doctors how serious the illness is and what actions to take next. Emergency dialysis can help to remove toxins from the body if needed.

Low Urea Creatinine Ratio

The following things may cause the urea creatinine ratio to be low:

  • Low protein in diet
  • Malnutrition
  • Liver damage
  • Drinking too much water
  • Muscle injury
  • Pregnancy
  • Cirrhosis

Tips for Keeping the Urea Creatinine Ratio in a Safe Range

Follow Your Diet Plan

If you have kidney disease, follow your low-protein diet plan to protect your kidneys. If you are a healthy person that uses a high protein diet, ask your doctor if you have any risks to eating high amounts of protein. Do not eat all your daily protein in one sitting, spread the amounts over the course of the day.

Rehydrate Properly

Drinking buckets of water is not a good way to rehydrate the body. Too much water can actually wash out more electrolytes and make you more dehydrated. If you need to get fluids in fast, use something that has electrolytes and solids likeelectrolyte replacement, decaffeinated teas, juices, or mineral water. Avoid caffeinated coffee, tea, and soda.

Keep Sodium in Check

In some diseases, sodium can put a strain on the kidneys and make them have to work harder. If you have a disease that requires restricted sodium intake (heart failure, kidney failure, heart disease) have your doctor give you information on a low sodium diet. There are many hidden sources of sodium in foods that you may not realize. Do not stop eating sodium unless you are directed to by your doctor. It is an important mineral to help your body maintain fluid balance. 

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