This page was reviewed under our medical and editorial policy by
Bradford Tan, MD, Chair, CTCA Department of Pathology and Laboratory Medicine.
This page was reviewed on September 25, 2022.
A patient's care team may order several blood tests to help detect, diagnose or treat cancer, or monitor the effects of treatment. Each test measures different substances in the blood. Blood tests may be performed every few weeks or months so the care team can compare the results over time.
It’s helpful to go over your test results with your cancer care team and ask them to explain the results to you. Make sure to ask any questions you have. You may also want to ask for a copy of the test results for your records.
Asking your care team questions about your tests is a great way to learn more about your care and treatment. Consider asking the questions below before and after the test.
Questions to ask before the test:
Questions to ask after the test:
A CBC test is one of the most common blood tests. It measures the main components of your blood.
A CBC test may be used to diagnose some blood cancers, such as leukemia. It’s also common to have a CBC test after you’ve been diagnosed, to help your care team get a bigger picture of your overall health.
A CBC test can help your care team:
White blood cells
These cells help your body fight infection. There are many different types of white blood cells, each with its own specific job. A CBC shows the levels of several types of white blood cells, called neutrophils, lymphocytes, monocytes, eosinophils and basophils. Your care team will pay close attention to your neutrophil level. Low levels of neutrophils may mean you’re at higher risk of an infection.
Red blood cells
These cells carry oxygen to cells throughout the body, and they carry carbon dioxide away from your cells. In addition to an overall red blood cell count, a CBC measures the levels of hemoglobin (a part of the red blood cell that is rich in iron) and hematocrit (the percent of red blood cells in the blood). Low levels of red blood cells indicate anemia, which can cause you to feel tired and lack energy. High levels may indicate dehydration.
Platelets
Platelet cells help your blood clot, which helps control bruising and bleeding when you have a wound or injury. Your platelet count can help your care team know if you’re at high risk for bleeding problems.
The numbers below show what the normal ranges for the main components of a CBC look like. Some components have different normal ranges for women and men.
Normal ranges for CBC components:
Keep in mind that there are many reasons that certain levels could be abnormal. Factors such as recent diet and activity may affect the results. Your cancer care team can help you understand your results, catch things early and avoid complications.
A comprehensive metabolic panel—also called a blood chemistry panel—is another type of blood test that measures 14 different substances in your blood. This blood test can help your care team get information about your metabolism, or how your body is using food and spending energy.
A CMP measures substances like:
Your care team may use a CMP to see how your body is responding to treatment. Some treatments can change the level of certain substances in your blood.
Some side effects from treatment—like vomiting and diarrhea—may cause you to be dehydrated, which can affect your blood chemistry, too. You won’t feel these changes in your blood chemistry level until it’s a bigger problem.
A CMP measures many different substances, and each one tells your care team something different about your body. Your care team may monitor electrolytes, for example, to see how you’re handling treatments and to make sure you’re not dehydrated. They may monitor certain waste products to see how well your kidneys or liver are working. And they may look at enzyme and protein results to see how your liver is functioning.
Check with your doctor, as you may need to fast before having a CMP.
Your care team may also order a basic metabolic panel (BMP) depending on the information they need. A BMP measures only eight of the substances that a CMP does and doesn’t include testing liver function and proteins.
Comprehensive metabolic panel normal ranges, according to the National Library of Medicine: