

Kidneys are among the most vital organs in the human body.
They work to filter blood, remove toxins, regulate blood pressure, and maintain fluid and mineral balance. That’s why kidney function tests are essential medical screenings, especially if you have chronic conditions like high blood pressure or diabetes.In this guide by Dalili Medical, we’ll take you through a simplified overview of everything you need to know about kidney function tests—Creatinine, Urea, and eGFR (estimated Glomerular Filtration Rate).
Kidney function tests are a group of lab tests that assess how well your kidneys are filtering waste, balancing minerals, and regulating fluids. The most commonly used tests include:
Creatinine
Urea (BUN – Blood Urea Nitrogen)
eGFR (Estimated Glomerular Filtration Rate)
Each test provides a unique insight into your kidney’s performance.
What is creatinine?
Creatinine is a waste product formed from muscle breakdown. It is filtered out of the blood by the kidneys and excreted in urine.
If levels rise in the blood, it could indicate reduced kidney function.
Normal creatinine levels:
Men: 0.7 – 1.3 mg/dL
Women: 0.6 – 1.1 mg/dL
✅ When does creatinine increase?
Acute or chronic kidney failure
Severe dehydration
Certain medications (e.g., NSAIDs, strong antibiotics)
What is urea?
Urea is a waste product formed in the liver when the body breaks down proteins. It is removed from the body through the kidneys.
Normal urea levels:
7 – 20 mg/dL
✅ When does urea increase?
Kidney dysfunction
High protein intake
Dehydration or internal bleeding
✅ When does urea decrease?
Advanced liver disease
Poor nutrition or low protein intake
What is eGFR?
eGFR is an estimate of how well your kidneys are filtering waste from your blood. It’s calculated using creatinine levels, age, sex, and sometimes race.
Normal eGFR ranges:
Above 90: Normal kidney function
60–89: Mildly reduced function
Below 60: Kidney dysfunction
Below 15: Kidney failure (end stage)
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When to get tested
How to prepare
Common symptoms
FAQs or conclusion for this article.
eGFR is crucial because it can detect gradual kidney deterioration before symptoms appear. It's one of the earliest and most reliable indicators of chronic kidney disease (CKD).
You should consider testing your kidney function if you:
Have diabetes or high blood pressure
Are taking medications that may affect the kidneys (e.g., NSAIDs used long-term)
Experience unexplained swelling in the legs or face
Feel persistent fatigue or have a low appetite
Are already diagnosed with chronic kidney disease (CKD)
Swelling in the feet, ankles, or around the eyes
Reduced urine output or changes in urine color
Foamy urine
Constant tiredness
Nausea or poor appetite
High blood pressure without an obvious cause
Most kidney function tests do not require fasting. However:
You may be asked to fast for 6–8 hours if these tests are combined with others, like blood sugar or lipid panels.
Hydrate well before the test to avoid overly concentrated samples.
Test | Normal Range | Elevated Levels May Indicate |
---|---|---|
Creatinine | 0.6–1.3 mg/dL | Kidney dysfunction, dehydration |
Urea (BUN) | 7–20 mg/dL | Kidney failure, internal bleeding, dehydration |
eGFR | 90+ | Normal kidney function |
❗ Note: Never rely on a single test. Repeat testing or follow-up with additional tests is often recommended for accurate diagnosis.
Yes — especially if the issue is caught early. Some lifestyle tips to support kidney health include:
Drinking adequate water daily
Reducing salt and excessive protein intake
Avoiding over-the-counter medications without doctor’s advice (especially NSAIDs)
Staying physically active
Managing blood sugar and blood pressure
Does a kidney test show kidney failure?
Yes. Significantly elevated creatinine and a very low eGFR (especially <15) indicate kidney failure.
Can kidney function return to normal?
In some temporary conditions like dehydration or mild infections — yes. In chronic cases, the goal is usually to slow the progression rather than reverse it.
Can kidney issues be detected before symptoms appear?
Absolutely. That’s one of the main benefits of regular kidney function tests — they allow early detection and prevent further damage.
✅ Conclusion
Kidney function tests — including Creatinine, Urea, and eGFR — are your gateway to understanding your kidney health and detecting any dysfunction early, before it worsens. If you're at risk or have noticed any warning signs, don’t hesitate to get tested and consult your doctor regularly.
Remember: The kidneys rarely show symptoms until it's too late — so take action and get tested today!