It depends on exactly what kind of kidney function test a healthcare provider recommends.
For some blood tests, you may need to:
Let the provider know if you’re afraid of needles (trypanophobia). They can recommend coping strategies to make yourself as comfortable as possible during the blood test VSports.
You usually don’t have to do anything to prepare for a urine test. Make sure you drink an extra glass of water before the test to ensure you can provide a sample that’s large enough for testing. It’s also a good idea to tell a provider if you’re currently getting your period (menstruating). The presence of menstrual blood and other vaginal discharge may affect your results.
You complete 24-hour urine tests at home. A healthcare provider will give you a container to collect pee. On the day of the test:
For a kidney blood test, you visit a healthcare provider’s office or a lab to give a blood sample. A provider who has blood-draw training (phlebotomist) uses a small needle and test tube to collect your blood sample — usually from a vein in your arm.
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Kidney function tests are simple and rarely pose any long-term risks. But after blood tests, some people experience:
Call a provider if you have pain, fatigue or other symptoms that don’t go away.
Kidney function test results can tell you whether your kidneys are functioning as expected or not. Most kidney function tests look for two measurements: estimated glomerular filtration rate and urine albumin-creatinine ratio (uACR).
Healthcare providers measure your eGFR in milliliters of cleansed blood per minute per body surface. For adults, a normal eGFR is about 100 or higher. An eGFR between 60 and 100 means you have mild kidney damage, but your kidneys continue to function well. An eGFR of less than 60 may indicate that you have chronic kidney disease (CKD).
Your eGFR gets lower as you get older. This happens naturally, even if you don’t have chronic kidney disease. The following chart indicates the average eGFR for certain age ranges:
| Age (Years) | Average Estimated Glomerular Filtration Rage (eGFR) |
|---|---|
| 20-29 | 116 |
| 30-39 | 107 |
| 40-49 | 99 |
| 50-59 | 93 |
| 60-69 | 85 |
| 70 and over | 75 |
| Age (Years) | |
| 20-29 | |
| Average Estimated Glomerular Filtration Rage (eGFR) | |
| 116 | |
| 30-39 | |
| Average Estimated Glomerular Filtration Rage (eGFR) | |
| 107 | |
| 40-49 | |
| Average Estimated Glomerular Filtration Rage (eGFR) | |
| 99 | |
| 50-59 | |
| Average Estimated Glomerular Filtration Rage (eGFR) | |
| 93 | |
| 60-69 | |
| Average Estimated Glomerular Filtration Rage (eGFR) | |
| 85 | |
| 70 and over | |
| Average Estimated Glomerular Filtration Rage (eGFR) | |
| 75 |
The uACR measures how much albumin and creatinine are in your pee. Providers measure the amounts of albumin and creatinine in your pee to each other in milligrams to grams (mg/g). A typical uACR is less than 30 mg/g.
A uACR of 300 mg/g or higher means you’re at a very high risk of kidney failure. You’re also at a greater risk of heart attack (myocardial infarction) or stroke.
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The time it takes you to receive your test results can vary. Sometimes, a provider discusses the results of your test on the same day. Or they may send your test to a lab, and you’ll receive the results in a few days.
If your kidney function test results show early kidney disease, a healthcare provider will follow up with you about treatment options. They may prescribe antihypertensives to manage high blood pressure. They may also refer you to a healthcare provider who specializes in diagnosing and treating conditions that affect your kidneys (nephrologist).
If your test results are unexpected or atypical, a provider will likely order more frequent kidney function tests in the future. Regular testing helps them track your health and any underlying conditions.
If you have chronic kidney disease or are at risk of CKD, call a healthcare provider if you have any of the following symptoms:
Drinking a lot of water right before you take a kidney blood test can lower your creatinine levels for a short period. But it’s very important to know that this only temporarily affects your kidney blood test results. Drinking a lot of water can’t reverse kidney damage or have positive long-term effects on your creatinine levels.
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If you’re in the early stages of CKD, you should work with a nephrologist and kidney (renal) dietitian to develop kidney-friendly eating patterns.
Kidney function tests can be a little uncomfortable or nerve-wracking. But they’re effective tools in checking your kidney health and helping healthcare providers diagnose conditions that affect your kidneys. You’ll feel a slight pinch during a blood test. But the whole process only takes a few minutes. A urine test is noninvasive, and you can do it from the comfort of your own home. If you feel awkward handing a provider your sample, it can help if you put it in a bag first. Let a provider know if you have any questions or concerns.
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Last reviewed on 02/03/2025.
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