Creatinine Test measures the level of creatinine in the blood and urine. During metabolism, wherein the food you take is digested and transformed into energy, a substance called creatine is formed. This substance is further broken down into another substance, creatinine. This is the waste product that the kidneys take out from the blood and excrete in the urine.
Diet and normal physical activities do not affect the rate of creatinine production. If the kidneys become impaired, the amount of this substance in the urine decreases while it increases in the blood.
There are three types of creatinine tests:
- blood creatinine level test
- creatinine clearance test
- blood urea nitrogen-to-creatinine ratio (BUN-to-creatinine ratio) test
Blood Creatinine Level Test indicates the function capacity of the kidneys by measuring how much creatinine is in your blood. If there is high creatinine level found, this means that the kidneys are not working properly. The amount of muscle tissue affects the amount of creatinine in the blood. Men, for example, have higher muscle tissues and therefore have higher creatinine levels than women.
Creatinine Clearance Test measures how well the kidneys remove the creatinine from the blood. This is the better indicator of the function of the kidneys than blood creatinine level test. This is done on blood and urine sample collected within 24-hour timeframe.
BUN-To-Creatinine Ratio Test measures both blood urea nitrogen (BUN) and blood creatinine levels. This is to determine whether there is any problem in the BUN and creatinine levels. The BUN test measures how much urea is in your blood. Urea refers to the waste product when protein is broken down. Like the creatinine, it shows the doctor if the kidneys are working properly.
The main purpose of all these tests is to see how well your kidneys are working. It can also help a doctor in detecting if there is any kidney disease. For those who are taking medicines that can lead to kidney damage, these tests are done to monitor how well the kidneys are coping. Moreover, it can also be used to check for severe dehydration. When a person is dehydrated, the BUN levels shoots up more than the creatinine levels. There becomes a high BUN-to-creatinine ratio that can lead to kidney disease and urine blockage.
Preparing For Creatinine Test
- Drink sufficient fluids during the 24-hour urine collection timeframe.
- For two days before undergoing creatinine test, a person should not engage in strenuous exercises.
- Coffee, tea and other diuretics are not advised as these cause the body to pass more urine than necessary.
- A day before the test, a person should not eat more than eight ounce of meat, especially beef. Other protein-rich foods must also not be consumed.