Measuring Kidney Health: The Role of Creatinine, Uric Acid, and Urea Nitrogen
What is...?
What is Creatinine?
Creatinine is a waste product generated from the digestion of dietary protein and the natural breakdown of muscle tissue. It is filtered out of the blood by the kidneys.1
What Do High Levels of Creatinine Mean?
Elevated creatinine levels on their own are likely not harmful, but they can serve as a marker of other health issues, such as chronic kidney disease (CKD).2
What Test Measures Creatinine Levels?
The serum creatinine test measures how well your kidneys are filtering blood and is commonly included in routine health checkups or as part of a basic or comprehensive metabolic panel. It is typically used to assess kidney function in individuals at high risk for chronic kidney disease (CKD) or those showing symptoms of acute kidney injury (AKI). The test is also useful for monitoring kidney function over time in people with CKD and can help healthcare providers determine if any medications need to be adjusted or discontinued.1 For this test, a lower number is better.3
How Should Serum Creatinine Test Results Be Interpreted?
While the serum creatinine test is common, it alone doesn’t fully reflect kidney health, as normal levels can vary based on age, sex, body size, and other factors. Some with normal creatinine levels may still have kidney disease, while others with high levels may not. The most accurate way to assess kidney function is through the estimated glomerular filtration rate (eGFR).1
| Factors Increasing Creatinine Levels (Lower eGFR)1 | Factors Decreasing Creatinine Levels (Higher eGFR)1 |
|---|---|
| Large amounts of cooked meat | Vegan or vegetarian diet |
| Creatine supplements | Low muscle mass |
| Recent high-intensity exercise | Pregnancy |
| High muscle mass (e.g., bodybuilding) | History of amputation or muscle wasting disease |
| Medications (e.g., cimetidine, ritonavir, trimethorprim) | Severe liver disease (e.g., cirrhosis) |
How Can Creatinine Levels Be Lowered?
If you have a kidney condition and elevated creatinine levels, it’s crucial to take action to protect your kidney health. Your doctor may suggest the following:
- Adopt a healthy lifestyle.
- Modify your diet to reduce strain on your kidneys.
- Limit intense physical activity.
- Avoid creatine supplements.
- Review all medications you’re taking, including over-the-counter drugs.2
Lower Your Creatinine Levels with Renadyl™
Taking a probiotic supplement like Renadyl, which is designed to break down creatinine and ease kidney stress, can help reduce creatinine levels.
What is Uric Acid?
Uric acid is a normal waste product in the body, created when purines break down. Purines are naturally occurring substances in the body and are also present in foods like liver, shellfish, and alcohol. Additionally, purines can form when DNA is broken down in the body.4 Blood transports uric acid to the kidneys, which filter most of it into the urine for elimination from the body.5
What Do High Levels of Uric Acid Mean?
If your body produces excess uric acid or fails to eliminate enough of it, you may become ill. High uric acid levels, known as hyperuricemia, can result in gout or kidney damage.5
What Tests Measure Uric Acid Levels?
Uric acid is usually measured in the blood using a blood test (serum uric acid) that is often included in routine health checkups, especially in older patients, those patients with kidney or heart disease, high blood pressure, and diabetes. The uric acid urine test measures the level of uric acid in the urine and is done if uric acid blood levels are elevated to determine the cause for elevated serum uric acid levels.5
How Should Serum and Urine Uric Acid Test Results Be Interpreted?
Normal Results
A normal range for uric acid in a blood test is usually between 3.5 and 7.0 milligrams per deciliter (mg/dL) and varies by age and sex. For women, the normal serum uric acid level range is 1.5 to 6.0 mg/dL, and for men it’s 2.5 to 7.0 mg/dL. However, the normal range can vary slightly between laboratories. Your lab report should show the range that your lab uses. High serum uric acid levels can increase the risk of gout. Doctors recommend that people with gout keep their uric acid levels below 6.0 mg/dL.
Normal urine uric acid values range from 250 to 750 mg/24 hours (1.48 to 4.43 mmol/24 hours), but can vary slightly between labs. Urine uric acid levels are measured when serum uric acid is outside the normal range and why. Consult your provider for specific results.
Abnormal Results
- Purine processing issues (e.g., Lesch-Nyhan syndrome)
- Metastatic cancers
- Muscle breakdown (rhabdomyolysis)
- Bone marrow disorders (myeloproliferative disorders)
- Gout
- High-purine diet
- Chronic kidney disease or glomerulonephritis
- Lead poisoning
- Chronic alcohol use5
How Can Uric Acid Levels Be Lowered?
To lower uric acid levels, it’s best to limit foods and drinks high in purines. Try to reduce your intake of:
- Red meat and organ meats
- Alcohol
- Beverages sweetened with high fructose corn syrup (like soda)
- Fish, especially shellfish like lobster and shrimp
A low-purine diet can help manage uric acid levels. Consult your provider for personalized advice on which foods and drinks to avoid, and for help creating a tailored diet and exercise plan.6
Lower Your Uric Acid Levels with Renadyl™
A probiotic supplement such as Renadyl can be beneficial, as it helps break down naturally occurring waste products, including uric acid, which can be harmful to the kidneys when present in high concentrations.
What is Urea Nitrogen?
Urea nitrogen is a waste product created when your body breaks down dietary protein. It forms in the liver, moves through the bloodstream to the kidneys, which filter it out, and is then excreted in urine.7
What Do High Levels of Urea Nitrogen Mean?
Urea nitrogen levels in the blood help healthcare providers assess kidney function. A small amount is normal, but high levels may indicate that your kidneys are not filtering it properly, potentially signaling a kidney-related condition.7
What Test Measures Urea Nitrogen Levels?
The blood urea nitrogen (BUN) test measures the amount of urea nitrogen in your blood, helping healthcare providers assess kidney function. BUN levels can vary based on age and sex, and abnormal levels may signal a health issue, such as kidney damage.7
How Should BUN Results Be Interpreted?
BUN test results are reported in milligrams per deciliter (mg/dL). Normal levels typically range from 7 to 20 mg/dL, though this can vary based on age and other health factors. Elevated BUN levels may indicate poor kidney function. Your doctor will evaluate your BUN results alongside other tests, like creatinine and eGFR, to determine the next steps.8
How Can BUN Levels Be Lowered?
The simplest way to lower high BUN levels is by adjusting your diet. If you don’t have kidney disease and aren’t on dialysis, increasing fluid intake is important, as dehydration can cause a rise in BUN levels even when serum creatinine is low. Men should aim for about 13 cups (3 liters) of fluids per day, while women should aim for around 9 cups (2.2 liters).
A low-protein diet can also help reduce BUN levels. Healthy low-protein food options include:
- Grains: Oats, rice, and pasta
- Fruits: Apples, berries, and bananas
- Vegetables: Leafy greens, peppers, and broccoli
- Healthy fats: Avocados, nuts, and coconut oil7
Lower Your BUN Levels with Renadyl™
Renadyl’s probiotics target the gut, gradually breaking down waste compounds like urea nitrogen over time. This process helps lower toxin levels in the body and reduces strain on the kidneys, which can lead to a decrease in BUN levels.
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.
References
- Creatinine. National Kidney Foundation. (2024, November 20). https://www.kidney.org/kidney-topics/creatinine
- What Do High Creatinine Levels Mean? Fresenius Medical Care. (n.d.). https://www.freseniuskidneycare.com/thrive-central/what-are-high-creatinine-levels
- Tests to Check Your Kidney Health. (2024, November 20) https://www.kidney.org/kidney-topics/tests-to-check-your-kidney-health
- Uric Acid (Blood). University of Rochester Medical Center’s Health Encyclopedia. (2024, November 20). https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=uric_acid_blood
- Uric Acid Urine Test. Icahn School of Medicine at Mount Sinai. (2024, November 20). https://www.mountsinai.org/health-library/tests/uric-acid-urine-test
- Hyperuricemia (High Uric Acid Level). Cleveland Clinic. (2024, November 20). https://my.clevelandclinic.org/health/diseases/17808-hyperuricemia-high-uric-acid-level
- Blood Urea Nitrogen Test (BUN). Cleveland Clinic. (2024, November 20). https://my.clevelandclinic.org/health/diagnostics/17684-blood-urea-nitrogen-bun-test
- Blood urea nitrogen (BUN) test for kidney disease. American Kidney Fund. (2024, November 20). https://www.kidneyfund.org/all-about-kidneys/tests/blood-urea-nitrogen-bun-test#what-does-my-bun-test-result-mean