What is BUN/Creatinine Ratio?
BUN/Creatinine ratio evaluates the balance of two biomarkers:
- BUN measures the amount of urea nitrogen in your blood, a waste product created when your liver breaks down protein.
- Creatinine measures the amount of creatine in your blood, which comes from normal muscle metabolism.
Since creatinine is almost entirely filtered and eliminated by the kidneys, while BUN is filtered but partially reabsorbed, the two markers respond differently when the kidneys are under strain. That’s why clinicians look at the BUN/creatinine ratio—not just the individual numbers—to understand whether the kidneys are stressed by factors like hydration, circulation, or illness, versus true kidney damage.
Why Does Bun/Creatinine Ratio Matter?
The BUN/Creatine ratio:
- Shows how hard your kidneys are working under everyday conditions
- Helps tell dehydration apart from kidney disease, so you get the right treatment
- Reflects how efficiently your kidneys are clearing waste from your blood
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How to Interpret Bun/Creatinine Ratio
(Ranges may vary slightly by lab)
Standard reference ranges represent the middle 95% of healthy individuals but don’t necessarily reflect levels associated with longevity. Optimal ranges are derived from clinical guidelines, peer-reviewed research, and real-world outcomes data, with an emphasis on levels associated with peak functioning and reduced disease risk.
Benefits of Optimizing Bun/Creatinine Ratio
- Improves kidney filtration, helping protect long-term kidney health
- Better hydration status, which supports circulation, energy levels, and healthy aging1
- Reduced cardiovascular and kidney strain
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Low BUN/Creatinine Ratio Levels
A low BUN/Creatinine ratio can reflect low protein intake or reduced liver function, both of which affect how waste products are produced and processed in the body.
Symptoms:
- Fatigue
- Muscle weakness
- Swelling
- Dizziness
- Nausea
Causes:
- Dehydration or overhydration
- Malnutrition or low protein intake
- Advanced liver disease
- Sickle cell anemia
- Hypothyroidism
- Rhabdomyolysis (severe muscle injury)
- Pregnancy
- Kidney damage or failure
Healthspan Impacts:
- May result in muscle wasting (sarcopenia)
- Reduced kidney function, which can accelerate biological aging and increases the risk of cardiovascular disease 2,3
High BUN/Creatinine Ratio Levels
A high BUN/Creatinine ratio can be linked to dehydration, heart-related circulation issues, or underlying kidney disease.
Symptoms:
- Swelling in the legs or ankles
- Fatigue
- Changes in urination
- Itchy skin
- Nausea and vomiting
Causes:
- Dehydration
- High protein intake
- Gastrointestinal bleed
- Kidney problems
- Heart failure
- Certain medications (e.g., antibiotics; corticosteroids)
Healthspan Impacts:
- Higher risk of death from any cause, especially in people with acute heart failure4
- Poorer outcomes in people with chronic conditions such as kidney injury or stroke5
- Can lead to reduced quality of life and functional capacity due to extreme fatigue, confusion, and muscle cramps
How Hone Treats Out of Range BUN/Creatinine Ratio
Your Hone physician will evaluate BUN/Creatinine ratio along with other biomarkers, your symptoms, and health history to determine treatment, which may include:
- IV therapy* – to improve dehydration
- ACE inhibitors* – to manage hypertension and protect kidney function
- Chronic condition management — addressing conditions like diabetes, high blood pressure, or heart disease
- Dialysis* – in more severe or persistent cases of acute kidney failure
*Your Hone Physician does not prescribe these treatments but will recommend further evaluation and help coordinate care with your primary care provider when medical treatment is indicated.
- Probiotics
- Omega-3 fatty acids
- Vitamin D
- Magnesium
- Moderate protein intake
- Reduce alcohol consumption
- Ensure adequate hydration
- Engage in physical activity
- Consume a fiber-rich diet, which can support kidney health
- Adjusting medications that may impact kidney function, such as NSAIDs
- Limit sodium intake to manage kidney strain and blood pressure6
- Monitor blood sugar levels
National Institutes of Health (2023). Link between hydration and aging. NIH Research Matters.
↑Zhang, M., et al. (2025). Renal aging and its consequences: Navigating the challenges of an aging population. Frontiers in Pharmacology.
↑Schlackow, I., et al. (2020). Long-term health outcomes of people with reduced kidney function in the UK: A modelling study using population health data. PLoS Medicine.
↑Sujino, Y., et al. (2019). Clinical implications of the blood urea nitrogen/creatinine ratio in heart failure and their association with haemoconcentration. ESC Heart Failure.
↑Huang, S., et al. (2022). Huang, S., et al. (2022). Association between the blood urea nitrogen to creatinine ratio and in‑hospital mortality among patients with acute myocardial infarction: A retrospective cohort study. Experimental and Therapeutic Medicine.
↑Cook, N. R., et al. (2020). Sodium and health-concordance and controversy. BMJ.
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Reviewed for Accuracy by Our Medical Review Board
This biomarker information has been reviewed by a member of Hone’s medical review board. As part of the medical review team, physicians fact-check this content against the latest research and their own experience treating their patients.
Ashley Winter, M.D., is a board-certified urogynecologist trained at Weill Cornell and Cleveland Clinic. She specializes in female and male sexual dysfunction, urinary issues, genital pain, and hormone therapy.
James Staheli, D.O., is the Medical Director for Broad Health, Hone Health’s affiliated medical practice and a family medicine doctor in Atlanta, Georgia.
