Kidney function tests (creatinine, urea, eGFR)
kidney function test · creatinine test · BUN · eGFR · renal panel
This is a blood test from a vein. It shows how well your kidneys clean your blood. eGFR is calculated from creatinine, age, and sex.
For high blood pressure, diabetes, swelling, before some scans with contrast dye, while taking certain medicines, or at a checkup.
⏱ Duration: the blood draw takes a few minutes; results usually come the next day
Be sure to tell your doctor
How to prepare
- Food. Usually fasting: no food for 8 to 12 hours. Plain water is fine. Check with the lab.
- The day before. No alcohol and no hard workouts. Do not eat a lot of meat in the evening.
- Medicines. Do not stop them on your own. Tell your doctor what you take. They will decide if anything should change.
What to bring
- Your test request form
- Your ID
- Past test results, if you have them
How it goes
- You sit down and rest your arm on the armrest
- A band is tightened above your elbow
- The skin is wiped with antiseptic
- A quick prick, and blood fills a tube
- The needle comes out, and a cotton pad is pressed on the spot
What you'll feel
- A quick prick, like a pinch
- Sometimes slight dizziness. Tell the nurse
Afterwards
- Press the cotton pad for 3 to 5 minutes and keep your arm straight
- You can eat right away and go back to your usual day
- Results usually come in 1 day. The lab will tell you when
- Sometimes the doctor adds a urine test to get the full picture
Common questions
What is eGFR?
It is an estimate of how much blood your kidneys clean each minute. It is based on creatinine, age, and sex.
Why can creatinine be high without illness?
It depends on muscle mass, meat in your diet, exercise, and how much water you drink. So your doctor draws the conclusions.