High BUN and Creatinine: Possible Causes and What To Do Next

High BUN (blood urea nitrogen) and creatinine levels may indicate that your kidneys aren’t functioning as well as they should. BUN and creatinine are waste products from the breakdown of proteins and muscle tissue, respectively–both pass through the kidneys for elimination.

In a healthy individual, the kidneys filter BUN and creatinine out of the bloodstream and eliminate them through urine. However, kidney problems can hinder this process, accumulating these waste products in the blood. However, problems with the kidney’s filtration system are not the only possible reason for high BUN and creatinine levels. 

Read on to learn more about the other potential causes and the best course of action if you find out that you have elevated BUN and creatinine.

Did You Know? You can access some of the most common lab tests for kidney health assessment in one space online. These include the BUN test and the creatinine, 24-hour urine test. 

What Are Considered High Bun and High Creatinine Levels?

Normal ranges can vary slightly between labs. Generally, a BUN level above 20 mg/dL and a creatinine level above 1.3 mg/dL for men or 1.1 mg/dL for women are considered high. On the other hand, a high BUN/creatinine ratio typically falls above 20:1. This means that the level of BUN in your blood is disproportionately higher than your creatinine level. 

However, keep in mind that interpreting these values should be in context with your overall health and medical history. Thus, it is a job exclusively reserved for a healthcare professional. 

Also Read: What Is a Dangerous High BUN Level? + 4 Ways to Lower It

What May Cause High BUN and Creatinine

The weight of having elevated BUN and creatinine levels on your renal health is too much for you to ignore its potential cause. Individual factors may influence the culprit, warranting the need for a more personalized diagnosis and treatment. That said, here are the common causes of these elevated levels–from kidney disease to factors like dehydration, diet, and medications, highlighting why paying attention to these markers is vital for your health.

1. Kidney disease or damage 

Kidney disease, in its various forms, is the most common cause of high BUN and creatinine. When these vital organs malfunction due to disease or damage, their ability to filter out BUN and creatinine becomes compromised, signaling that your kidneys need attention.

Also Read: What Do Your Nails Look Like With Kidney Disease?

2. High-protein diet 

Eating a diet very high in protein increases the workload for your liver and kidneys. Your liver produces more urea (a waste product generated during protein digestion), and your kidneys must work harder to filter it out. This can lead to a temporary increase in BUN levels, even if your kidneys are functioning normally.

3. Dehydration 

Dehydration leads to a lower blood volume, making it more difficult for the kidneys to filter out waste products like BUN and creatinine effectively.  Similarly, when the kidneys have less fluid to work with, they struggle to remove these waste products efficiently, causing them to build up in the bloodstream.

4. Certain medications 

While medications are crucial for treating various health conditions, it’s important to know that some can impact kidney function.  Certain antibiotics, for example, are known to potentially cause kidney damage⁽¹⁾, especially with prolonged use or high doses. This is because the kidneys play a key role in filtering medications from the bloodstream, and some antibiotics can strain this process, leading to inflammation or other issues.

Steroids, often used to reduce inflammation and suppress the immune system, can also affect the kidneys. Long-term steroid use⁽²⁾ can increase blood pressure and blood sugar levels, both of which are risk factors for kidney disease. In some cases, steroids can even cause a condition called steroid-induced nephropathy, which directly damages the kidney’s filtering units.

5. Other conditions 

Kidney dysfunction may be the primary driver of high BUN and creatinine, but other health conditions can also contribute to these elevated levels. For instance, congestive heart failure⁽³⁾, where the heart pumps blood with strain, can reduce blood flow to the kidneys, hindering their ability to filter waste products and leading to a buildup of BUN and creatinine. 

Likewise, a blockage in the urinary tract, such as a kidney stone or enlarged prostate, can impede urine flow and cause pressure to build up within the kidneys. This pressure can impair kidney function and elevate BUN and creatinine levels.

6. Frequent strenuous activities

Even something as common as a recent intense workout can temporarily affect these levels.  During intense exercise, muscle breakdown increases, releasing more creatinine into the bloodstream.  Additionally, strenuous activity can lead to temporary dehydration, further increasing the BUN and creatinine levels.  

What to Do if You Have High Creatinine and BUN

Receiving blood test results showing elevated creatinine and BUN levels can be concerning, but it’s important to remember that it’s not a time to panic. Instead, consider it a signal to take proactive steps toward understanding and addressing the underlying cause. 

These elevated levels often indicate a potential issue with kidney function, and early intervention is crucial for protecting your kidney health and overall well-being.

1. Consult Your Doctor

Receiving news of high creatinine and BUN levels can be concerning, but it’s important to approach the situation with a calm and proactive mindset. While it’s important not to ignore these results, it’s equally important not to panic. 

Make an appointment with your doctor or a nephrologist (kidney specialist) to discuss the results. Your doctor will review your medical history, medications, and lifestyle to pinpoint the potential reasons for the elevated levels. Be prepared for additional tests, such as a urinalysis, kidney imaging, or a glomerular filtration rate (GFR) test, to assess kidney function and identify any underlying issues. 

Did You Know? You can book additional blood tests to help your doctor better assess your kidney health online. You can access these tests with just one click.

• Urinalysis
• Kidney function blood test

2. Monitor Your Levels

Monitoring your BUN and creatinine levels can help track your kidney health and the effectiveness of any interventions. The frequency of these blood tests will depend on the underlying cause of your elevated levels and the severity of your condition. 

For instance, if you have chronic kidney disease, your doctor might recommend more frequent monitoring than someone who experienced a temporary increase due to dehydration. Plus, keeping a detailed record of your BUN and creatinine levels empowers you to actively participate in your care. 

3. Stay Informed and Proactive

Taking charge of your kidney health involves becoming an informed and proactive patient.  Empower yourself by learning about how your kidneys function, the factors that can contribute to kidney disease, and the warning signs to watch out for. 

Understanding the role of diet, exercise, hydration, and other lifestyle factors can help you make healthy choices that support your kidneys.  Early detection of kidney problems can also prevent or slow down the progression of the disease, so familiarize yourself with potential symptoms and risk factors.

4. Follow Medical Advice

If your high BUN and creatinine levels are linked to underlying health issues like diabetes or high blood pressure, effectively managing those conditions becomes a top priority in protecting your kidney health.  Additionally, your doctor might adjust your medications or explore alternative options if they suspect these are contributing to the problem.  

Beyond addressing specific conditions, your doctor will likely recommend lifestyle changes to support kidney function. These changes often include dietary adjustments, such as reducing protein and salt intake, incorporating regular exercise to improve overall health, and focusing on weight management to lessen the burden on your kidneys.

Also Read: 7 Highly Recommended Tips To Keep Your Kidneys Healthy

Recent Developments in Understanding Abnormal BUN and Creatinine Levels

The fundamental causes of high BUN and high creatinine levels have long been established and studied. However, recent clinical and research data provided a more in-depth understanding of how to better interpret these parameters, along with potential novel advancements in determining its other effects, risks, and possible early detection procedures.

1. Creation of the kidney disease models

The Kidney Tissue Atlas of the Kidney Precision Medicine Project (KPMP) has made breakthroughs in creating precise models or maps of kidney disease. This is a significant step forward, as not all kidney issues affect the body similarly. Understanding the specific mechanisms by which kidney disease forms can lead to targeted treatments that address the root causes of BUN/creatinine buildup rather than just the symptoms. 

These models, often called “kidney organoids” or “mini-kidneys,” are three-dimensional structures grown in the lab from human cells. They mimic the intricate architecture of the kidney, including the filtering units (nephrons) and the surrounding tissues. Therefore, it allows researchers to study kidney diseases in a more realistic and human-relevant setting.

Source: National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)⁽⁴⁾

2. BUN/creatinine ratio in specific conditions 

A 2023 Chinese study discovered that the ratio of blood urea nitrogen (BUN) to creatinine, a standard kidney function parameter, could be an early warning sign for type 2 diabetes. It could be due to the kidneys’ role in filtering waste products and regulating fluid balance, which is crucial for maintaining metabolic equilibrium. 

This finding challenges the traditional view of BUN and creatinine as solely indicators of kidney health, suggesting a more complex interplay with other bodily systems. Additionally, it shows how these markers aren’t just about kidney function in isolation but can reflect complex interactions with other diseases. This could lead to earlier detection or even preventative measures.

Source: Medicine (Baltimore)⁽⁵⁾ 

3. New biomarkers for acute kidney injury (AKI) 

Researchers are actively exploring new biomarkers beyond BUN and creatinine to detect AKI earlier and more precisely. Traditional markers like BUN and creatinine can lag behind actual kidney damage, sometimes delaying crucial interventions. That’s why researchers find it valuable to further search for new biomarkers that can signal AKI sooner and with greater accuracy.

For example, studies investigate molecules like NGAL (neutrophil gelatinase-associated lipocalin) and KIM-1 (kidney injury molecule-1), which may signal kidney damage sooner.  This research aims to improve early intervention and prevent progression to chronic kidney disease.

Source: Annals of Intensive Care⁽⁶⁾

4. BUN/Creatinine Ratio and Stroke Outcomes

A study published in Frontiers in Neurology in April 2024 explored the link between the BUN/creatinine ratio and 3-month outcomes in patients with acute ischemic stroke. They found that an elevated ratio was associated with poorer outcomes, potentially due to dehydration and its impact on cerebral blood flow. 

Why is this significant?  Dehydration can negatively impact cerebral blood flow, which is crucial for brain health and recovery after a stroke. When the body lacks enough water, blood volume decreases and can become thicker. This makes it harder for blood to reach and nourish brain tissue, especially areas already compromised by the stroke. 

Source: Frontiers in Neurology⁽⁷⁾

Recent research highlights the interconnectedness of abnormal BUN and creatinine levels with kidney function, hydration, and overall health. These findings lead to improved early detection methods and a deeper understanding of how these markers influence cardiovascular and overall health. These developments pave the way for new treatments and personalized interventions.

Frequently Asked Questions

Which fruit is best for lowering creatinine?

While no single fruit can directly lower creatinine, incorporating fruits like berries, apples, and grapes into your diet can support kidney health. These fruits offer antioxidants and fiber, which may indirectly contribute to managing creatinine levels. However, it’s important to remember that a kidney-healthy approach involves a comprehensive strategy, including medical guidance and addressing underlying conditions.

Can vitamins cause high creatinine levels?

While most vitamins are safe and essential for health, certain vitamins and supplements can influence creatinine levels. Excessive doses of vitamin D or creatine supplements may lead to elevated creatinine levels, sometimes without indicating actual kidney damage. Consult your doctor about appropriate vitamin intake and any potential impact on kidney health.

How do you treat high BUN and creatinine?

Managing high BUN and creatinine requires addressing the underlying cause, such as kidney disease or heart failure. Treatment often involves lifestyle changes, including dietary adjustments, increased fluid intake, and medication to support kidney function and overall health.

The Bottom Line

Staying informed about kidney health is key to overall wellness. While high BUN and creatinine levels can be concerning, they also serve as valuable wake-up calls, prompting us to take proactive steps toward better health. In addition, new advances concerning BUN and creatinine continue to illuminate their significance and the importance of seeking medical attention. 

Sources:

¹ Campbell RE, Chen CH, Edelstein CL. Overview of Antibiotic-Induced Nephrotoxicity. Kidney Int Rep. 2023 Aug 25;8(11):2211-2225. doi: 10.1016/j.ekir.2023.08.031. PMID: 38025228; PMCID: PMC10658282.

² Albakr, R. B. (2024). Steroid‐Induced Hyperosmolar Hyperglycemic Syndrome in a Young Patient Without Diabetes After Treating Him for Minimal Change Disease—Case Report. Clinical Case Reports, 12(11), e9599. https://doi.org/10.1002/ccr3.9599

³ Mohamed Sakr, A. R., Elsayed Gomaa, G. F., El Wasif, S. M., & Hosny Eladawy, A. H. (2023). The prognostic role of urea-to-creatinine ratio in patients with acute heart failure syndrome: A case–control study. The Egyptian Heart Journal, 75, 78. https://doi.org/10.1186/s43044-023-00404-y

⁴ National Institutes of Health (2023, July 19). New atlas of human kidney cells to help unlock kidney disease research. Retrieved December 21, 2024, from https://www.nih.gov/news-events/news-releases/new-atlas-human-kidney-cells-help-unlock-kidney-disease-research

⁵ Yin, X., Wang, Y., Jiang, J., Zhong, F., & Zhang, Q. (2024). Association of blood urea nitrogen to creatinine ratio with incident type 2 diabetes mellitus: A retrospective cohort study in the Chinese population. Medicine, 103(30), e39003. https://doi.org/10.1097/MD.0000000000039003

⁶ Ostermann, M., Legrand, M., Meersch, M., Srisawat, N., Zarbock, A., & Kellum, J. A. (2024). Biomarkers in acute kidney injury. Annals of Intensive Care, 14(1), 1-12. https://doi.org/10.1186/s13613-024-01360-9

⁷ Liu, H., Chen, Y., Zhou, Q., Guo, G., Hu, B., Wan, F., & Wen, J. (2024). Association between the blood urea nitrogen-to-creatinine ratio and 3-month outcomes in patients with acute ischemic stroke: A secondary analysis based on a prospective cohort study. Frontiers in Neurology, 15, 1350116. https://doi.org/10.3389/fneur.2024.1350116