The level of creatinine in the blood is measured by a serum creatinine test. When creatine, which is found in your muscle, breaks down, a waste product called creatinine is formed. Your urologist can get information about how well your kidneys are working by measuring creatinine levels in the blood.
There are millions of small blood-filtering units called nephrons in each kidney. Blood is continuously filtered by the nephrons through a very tiny cluster of blood vessels known as glomeruli. Waste products, excess water and other impurities are filtered out of the blood by these structures. The bladders store the toxins which are removed during urination.
The substances that your kidneys normally eliminate from the body include creatinine. The level of creatinine in the blood is measured by a kidney doctor to check kidney function. It indicates that your kidney is damaged and not working properly if high levels of creatinine are found.
Along with several other laboratory tests, serum creatinine tests are usually performed. To help diagnose certain diseases and to check for any problems with your kidney function, during routine physical exams these tests are done.
Why is a serum creatinine test done?
If you show signs of kidney disease, your urologist may order a serum creatinine test to assess your creatinine level. The symptoms include the following:

  • Fatigue and trouble sleeping

  • A loss of appetite

  • Swelling of the face, wrists, ankles or abdomen

  • Lower back pain near the kidneys

  • Changes in urine output and frequency

  • High blood pressure

  • Nausea

  • Vomiting

With different diseases or conditions, kidney problems can be related. These include:

  • An inflammation of the glomeruli due to damage (glomerulonephritis)

  • A bacterial infection of the kidneys (pyelonephritis)

  • Prostate disease such as an enlarged prostate

  • Urinary tract blockage, a reason of which may be kidney stones

  • Kidneys receiving less blood, a reason of which may be kidney stones

  • Decreased blood flow to the kidneys, which may be caused by congestive heart failure, diabetes or dehydration

  • The death of kidney cells as a result of drug abuse

  • Streptococcal infections, such as post-streptococcal glomerulonephritis

In some people, gentamycin (Garamycin, Gentasol) and other aminoglycoside medications can cause kidney damage. Your kidney specialist may order regular serum creatinine tests to make sure your kidneys remain healthy if you are taking this type of medication.
How do you prepare for a serum creatinine test?
Much preparation isn’t required for a serum creatinine test. It isn’t necessary to do fasting. Normally you can eat and drink like you do regularly. If you are currently taking any prescribed or over-the-counter (OTC) medications, you must tell your doctor about that. You may be asked by your urologist to stop taking your medication or to adjust your dosage before the test.
What can you expect during a serum creatinine test?
A sample of blood is taken by inserting a needle into a vein of your arm during serum creatinine test.
What do your serum creatinine test results mean?
In milligrams per deciliter or micromoles per liter, results of the creatinine blood test are measured. Although the normal range for creatinine may vary by gender and age, usually it may be 0.84 to 1.21 milligrams per deciliter (74.3 to 107 micromoles per liter). Men usually have higher creatinine levels than women as the amount of creatinine in the blood increases with muscle mass.
Generally, it means that your kidneys are not working well if your serum creatinine level is high. If you are dehydrated, have a low blood volume, by eating a large amount of meat or taking certain medications, your creatinine level may temporarily increase. The same effect can be caused by the dietary supplement creatine.
When kidney damage is a concern as your serum creatinine level is higher than normal, it is important to control the conditions contributing to the damage. Medication may be often used to manage your blood pressure which is very important. With kidney treatment, you may be able to prevent further kidney damage. But the fact is that you can’t undo permanent kidney damage.