A creatinine test checks the creatinine levels in the blood or urine, which indicates how well the kidneys are functioning. It can be done as a combination of blood test (serum creatinine test) and a creatinine urine test.
Creatinine is a chemical compound found in your bloodstream that comes from the energy-producing processes of muscles. Normal, healthy kidneys filter creatinine out of your blood and it exits your body as a waste product in urine.
How it works
A creatinine clearance test measures how well your kidneys filter the compound out of your bloodstream into urine.
To measure creatinine, a serum (blood) sample and urine samples are collected from you within a 24-hour period.
If the results show that your creatinine clearance levels are lower than the typical range for your age group, it may be a sign of:
Poor kidney function
Conditions that affect blood flow to your kidneys
Kidney problems, such as damage to the kidneys' filtering units (glomeruli)
Urinary tract obstruction, such as kidney stones
Normal creatinine clearance levels
The normal range for a creatinine blood test depends on your age, gender and number of kidneys:
If you are a/an...
The normal range is...
0.6 – 1.2mg of creatinine per deciliter (dL) of blood
0.5 – 1.1mg of creatinine per dL of blood
Person with only 1 kidney
It can vary depending on the health of the remaining kidney, usually ranging 1.2 – 1.9mg of creatinine per dL of blood
High creatinine levels
The following creatinine levels may indicate severe kidney impairment:
2.0mg or more in babies
5.0mg or more in adults
Why do you need a creatinine level clearance test?
Your doctor may order a creatinine test to:
Detect side effects of drugs, such as kidney damage or changes in kidney function
Screen for kidney disease if you have pre-existing conditions that increase risk of kidney problems, such as diabetes or high blood pressure (hypertension)
Diagnose or check the progression of kidney disease
Monitor how a transplanted kidney is functioning
Check the effectiveness of treatment
Chronic kidney disease can sometimes be a ‘silent’ condition. There may be no obvious symptoms until the disease is quite advanced. Creatinine levels can help your doctor determine how well your kidneys are working.
A creatinine blood test is often performed together with a blood urea nitrogen (BUN) test.
Blood urea nitrogen level is another indicator of kidney function. If kidney function is impaired, metabolic byproducts like urea can build up.
Compared to creatinine levels alone, the BUN-to-creatinine ratio provides more precise information about kidney function and its possible causes. As BUN also increases with dehydration, this can help your doctor check for other problems, such as dehydration.
How do you prepare for a creatinine level clearance test?
Your doctor may ask you to do the following:
Fast overnight before the test
Collect urine over 24 hours in containers provided by the clinic
Avoid eating meat for 24 hours before the test
Stop any medication or dietary supplement that may affect your creatinine levels
What can you expect in a creatinine level clearance test?
For a serum creatinine test (blood test), a blood sample will be taken from you via a vein in your arm.
For a urine test, you will need to either:
Provide a single sample in the clinic
Collect samples at home over 24 hours and return them to the clinic
After the procedure
Creatinine is considered to be a fairly reliable indicator of kidney function. Well-functioning kidneys will be able to maintain blood creatinine within a normal range.
In contrast, impaired kidneys will not be able to clear creatinine efficiently, leading to a rise in the creatinine level in our blood. Hence, abnormally high levels of creatinine are an indicator of possible malfunction or failure of the kidneys.
Your doctor will discuss your results with you and explain how this affects your diagnosis or treatment plan. This may include dialysis to remove wastes, salts and excess fluid from you blood.
Why choose Gleneagles Hospital?
At Gleneagles Hospital, our specialist team of nephrologists are known in Singapore and the region for their expertise in treating complex kidney conditions.
Patients undergoing creatinine level clearance tests will be provided with high standards of care in diagnosing and treating their renal condition.
Our kidney specialists are proficient in helping patients return to good renal health with their experience in diagnosing and treating a wide range of kidney-related conditions. Our dedicated team will work closely to support you during every step of your journey to recovery.