Understanding Cancer-Related Tests: Kidney Function Test

The kidneys are important organs responsible for filtering blood and clearing out waste from the body through urine and regulating fluid and electrolytes. They also produce substances that control blood pressure, red blood cells to carry oxygen throughout the body, and vitamin D needed by the bones and muscles.

Together, the following tests give information about how well the kidneys are working. Because some cancers and treatments can cause damage to the kidneys, your oncology team may monitor these tests frequently during and after your treatment.

While these tests are important, normal estimates of kidney function can be impacted by many non-disease related factors including age, race, diet, body size, and sex. Other tests may be needed to better determine the cause of any kidney related problems. 

Kidney function tests are part of the Basic Metabolic Panel and Complete Metabolic Panel. However, these tests can also be ordered independently by your physician. 

 Serum Creatinine (Cr) and Blood Urea Nitrogen (BUN) 

  • Bun and Cr are both waste products removed by the kidney. Measuring them helps determine how well the kidneys are doing their job removing waste products through urine. 

  • High levels of Cr or BUN may indicate that there is a problem with the kidneys. 

  • There may be no symptoms present with a high serum creatinine level, or you could experience symptoms including:  

    • Blood in the urine 

    • Fatigue 

    • Flank pain – or pain in the mid-lower back 

    • Swelling 

    • High blood pressure 

    • Urinating less than normal 

    • Dark colored urine 

    • Dehydration 

When to contact your doctor, health care provider, or Iris oncology nurse 

  • You are experiencing fever (temperature ≥100.4) 

  • You have unusual bleeding, bruising, or red spots under your skin 

  • You are experiencing dizziness or shortness of breath 

  • You have concerns about any symptoms that you are experiencing 


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Mayo Clinic Staff. (2020, February 21). Liver disease. Mayo Clinic. Retrieved January 19, 2022.

OncoLink Team. (2020). Comprehensive metabolic panel. OncoLink. Retrieved January 19, 2022.

Yin, L. K., & Tong, K. S. (2009, August 31). Elevated alt and AST in an asymptomatic person: What the primary care doctor should do? Malaysian family physician: the official journal of the Academy of Family Physicians of Malaysia. Retrieved January 19, 2022.