Also Known as: urine creatinine
What is a creatinine urine test?
This test measures the amount of creatinine present in the urine. Creatinine is a waste product produced by your muscles during regular activity. Your kidneys normally filter creatinine from your blood and excrete it in your urine. If your urine creatinine levels are higher than usual, you may have renal disease. The amount of creatinine in a blood sample is measured using a serum creatinine test. A urine creatinine test measures the total amount of creatinine in all urine produced over 24 hours. The level of creatinine can indicate how well the kidneys are functioning.
What is the test used for?
A creatinine test is performed to determine whether or not your kidneys are functioning normally. It's frequently ordered in conjunction with another kidney test called blood urea nitrogen (BUN) or as part of a comprehensive metabolic panel (CMP). A CMP is a collection of tests that provide information on the body's different organs and is usually a part of a routine checkup.
Creatinine levels can be measured for screening, diagnosing, and monitoring kidney diseases.
Screening: is the process of detecting health problems before they manifest as signs or symptoms. A creatinine test may be ordered to detect an issue early in individuals at higher risk of kidney disease.
Diagnosis: After symptoms have developed, testing is done to determine the underlying cause. Creatinine can be checked to assist diagnose symptoms related to kidney diseases such as swelling in the feet, urinary irregularities, loss of appetite, and fatigue.
Monitoring: is the process of how doctors track a patient’s condition over time. A creatinine test can provide information about how the disease may progress for people with kidney disease.
More than just a creatinine test is used to screen, diagnose, and monitor kidney diseases in many cases. For example, creatinine may be measured to determine the estimated glomerular filtration rate (eGFR), which measures how well the kidneys filter the blood.
Why and when do you need this test?
If you experience symptoms of kidney disease, you may need this test. These are some of them:
- Swelling (Puffiness) around the eyes
- Swelling of the ankles or feet
- Loss of appetite
- Painful and frequent urination
- Bloody or foamy or urine
If you have certain risk factors for kidney disease, you may also need this test. You may be at a higher risk for kidney disease if you have any of the following:
- High Blood Pressure
- Diabetes type 1 or type 2
- Family history of kidney disease
You may receive periodic creatinine testing to check for the adverse effect of certain medications if you are taking some that have the potential to disrupt renal function or if you've ever had an abnormal kidney function test or have been diagnosed with kidney disease, creatinine testing can be performed to monitor your kidney health.
What kind of sample is required for the test?
You will be asked to collect all of your urine during 24 hours. You will be given a container to collect your urine and instructions on collecting and keeping your samples by a laboratory specialist. The following steps are usually included in a 24-hour urine sample test:
- In the morning, empty your bladder and flush the urine away. Keep track of the time.
- Save all of your urine passed in the container provided for the following 24 hours.
- Refrigerate or place the urine container in a chiller with ice.
- As directed, return the sample vial to the laboratory.
Do you need to prepare for the test?
You may be asked not to eat cooked meat for 24 hours before your test, as cooked meat has been proven in research studies to elevate creatinine levels temporarily. Because some medications and supplements might affect creatinine levels, your doctor may advise you to change your medication regimen before a creatinine test. Before getting a creatinine test, talk to your doctor about any prescriptions, over-the-counter medications, or dietary supplements you're using. Make sure to go through the guidelines with your doctor or nurse for a 24-hour urine collection. While this collection can be inconvenient, collecting your urine samples accurately over this period is critical for accurate results.
Are there any risks to this test?
Having a urine test carries no risk, and you should not have any adverse effects or restrictions after completing a 24-hour urine collection for a creatinine test.
What do the test results mean?
Creatinine tests are usually used to assess kidney function. Creatinine levels are stable under normal conditions, suggesting regular muscle action and filtering or eliminating creatinine from the bloodstream. For urine creatinine, the American Board of Internal Medicine recommends the following reference ranges:
- 15-25 milligrams per kilogram of body weight (mg/kg) per 24 hours in urine
When creatinine levels rise to abnormally high levels, it could mean that the kidneys aren't filtering the blood effectively. The creatinine level can be used to determine your estimated glomerular filtration rate, which is a method of determining kidney function. Abnormal creatinine levels generally suggest renal disease or another condition that affects kidney function. These are some of them:
- Kidney infection caused by bacteria
- Urinary tract obstruction
- Autoimmune diseases
- Heart Failure
- Diabetes complications
- Certain disease-causing muscular problems
- Complications of pregnancy
However, abnormal results aren't always indicative of kidney disease. Creatinine levels can be temporarily raised in the following conditions:
- Intense exercise
- A diet rich in red meat
- Certain medications cause creatinine levels to rise as an adverse effect.
- A person's total muscle mass influences creatinine levels because it is a byproduct of muscle activity. Test results of Amputees, bodybuilders, obese, malnourished people and others with greater or less muscle mass may be affected by this.
- Creatinine levels are often lower in older persons due to a reduction in muscle mass.
Your healthcare provider may also order a creatinine clearance test. The creatinine level in the blood is compared to the creatinine level in the urine in a creatinine clearance test. Therefore, it may provide more accurate information on kidney function.
It is always recommended to consult your health care provider if you have any questions regarding your tests results.
Related tests: Estimated Glomerular Filtration Rate (eGFR), Comprehensive Metabolic Panel test (CMP), Basic Metabolic Panel test (BMP), Creatinine Clearance, Blood Urea Nitrogen (BUN), Urine Albumin and Albumin to Creatinine Ratio