What is a Creatinine Test?
Also known as a serum creatinine test, it is a way for doctors to measure how well your kidneys are working. Creatinine is a waste product from the normal breakdown of muscle tissue. As your body makes it, it filters through your kidneys and leaves in urine. Your kidneys‘ ability to handle creatinine is called the creatinine clearance rate, and this helps estimate how fast blood is moving through your kidneys, called the glomerular filtration rate (GFR).
Why take a Creatinine Test?
Your doctor or other health care provider may order a creatinine test for the following reasons:
- Diagnose if you have signs or symptoms of kidney disease
- Screen for kidney disease if you have diabetes, high blood pressure or other conditions that increase the risk of kidney disease
- Check for kidney disease treatment or progression
- Monitor for side effects of drugs that may include kidney damage or altered kidney function
- Check the function of a transplanted kidney
What you can expect for your Creatine Test?
For a serum creatinine test, a provider will take a blood sample by inserting a needle into a vein in your arm.
For a Urine tests you’ll need to provide a single sample in the clinic.
Different Types of Creatine Test Results
Results from creatinine in blood or urine are measured and interpreted in many ways, including the following:
Serum creatinine level
Creatinine usually enters your bloodstream and is filtered from the bloodstream at a relatively constant rate. The amount of creatinine in your blood should be relatively stable. An increased level of creatinine may be a sign of poor kidney function.
Typical range for serum creatinine:
- For adult men, 0.74 to 1.35 mg/dL (65.4 to 119.3 micromoles/L)
- For adult women, 0.59 to 1.04 mg/dL (52.2 to 91.9 micromoles/L)
Glomerular filtration rate (GFR)
Glomerular filtration rate is the measure of serum creatinine may also be used to estimate how quickly the kidneys filter blood. Because of variability in serum creatinine from one person to another, the GFR may provide a more accurate reading on kidney function.
This is a measure of how well the kidneys filter creatinine out of the bloodstream for excretion in urine
Typical range, by age, for creatinine clearance in women:
- 18 to 29 years: 78 to 161 mL/min/BSA
- 30 to 39 years: 72 to 154 mL/min/BSA
- 40 to 49 years: 67 to 146 mL/min/BSA
- 50 to 59 years: 62 to 139 mL/min/BSA
- 60 to 72 years: 56- to 131 mL/min/BSA
Standard measures have not been determined for older adults.
Another interpretation of urine creatinine count is known as the albumin/creatinine ratio. Albumin is a protein in blood. Healthy kidneys generally don’t filter it out of the blood, so there should be little to no albumin found in the urine.
Healthy Kidney Results
- For adult men, less than 17 mg/g
- For adult women, less than 25 mg/g