There are so many terms to become familiar with when discussing or experiencing kidney disease. Many medical terms will be tossed around, and sometimes it’s hard to know what each one means. Creatinine is one such term you may not be familiar with unless you have a medical background or are dealing with kidney problems. It is a waste product which is generated by the body during digestion of certain foods, namely meats, and muscle movement. Kidneys that are functioning properly are tasked with removing such waste products from the body by way of urination. However, in kidneys that are impaired, this isn’t the case and eventually the creatinine starts to build up. High creatinine levels can be indicative of something as benign as high muscle tone or it could be a warning sign of potential kidney problems as well as diabetes.

Doctors typically do not test specifically for creatinine unless they are asked to by their patients or have some reason to suspect potential kidney issues or diabetes. In the event that a doctor does order the test, the doctor would then proceed to collect a urine sample and determine the creatinine clearance rate, which is essentially just a measurement of how well the body is filtering creatinine based on how much is present in the urine.

This specific type of urine test requires the person being tested to collect all urine they produce throughout a 24-hour period. As mentioned above, creatinine at higher than normal levels may be a sign of kidney damage, but the creatinine levels produced by each person vary widely depending on all sorts of things such as age, size, race and gender. Just knowing the amount of creatinine is a good first step, but the second order of business would be to determine the cause of these elevated values, which requires further testing.

One such test would take a look at the serum creatinine, which is the amount of creatinine in a person’s blood. This test uses the glomerular filtration rate (or GFR) and measures creatinine in either grams per day or millimoles per day.

Normal ranges are:

  • for males, 0.8–1.8 g/day or 7.0–16.0 mmol/day
  • for females, 0.6–1.6 g/day or 5.3–14.0 mmol/day

These reference ranges may differ depending on the laboratory used but are fairly typical. 

It does bear repeating, however, that higher creatinine levels don’t necessarily mean something awful. Sometimes it can be indicative of high protein diets or an overly muscular physique.

In preparing for the test, here are a few things to discuss with your doctor:

  • A list of supplements and medicines you are taking
  • What time you should begin the collection process
  • If you need to avoid any specific beverages or food items.
  • Where you’ll be depositing the sample.
  • Whether you’re pregnant or might be pregnant. 

Your doctor will provide you with specifics for how to proceed, but the standard guidelines are:

  • Record both time and amount of first urination, but do not collect it. Doing so will allow you to start the 24-hour process on an empty bladder.
  • Collect each time you urinate throughout the next 24 hours and store sample in refrigerator.
  • Try to urinate at the same time you began the collection process the day before.
  • Seal sample container and try to get it to lab as soon as possible.

With the right guidance and accurate testing, your doctor can alert you to any looming kidney issues which is vital to any kidney disease sufferer’s prognosis, as once function progressively deteriorates, it’s usually gone forever. For more information about the tests and other procedures involved in kidney care, be sure to subscribe to our newsletter!