This page was reviewed under our medical and editorial policy by
Bradford Tan, MD, Chair, Department of Pathology and Laboratory Medicine, City of Hope Atlanta, Chicago and Phoenix
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.
This article will cover:
Yes, it’s possible to still have cancer despite normal blood tests, since routine blood work alone can’t detect most cancers. Leukemia is the only cancer that may be detected in routine blood work.
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 test results with the cancer care team and ask them to explain the results. That's also a good time to ask any questions and request a copy of the blood work results for the patient's records.
Asking the care team questions about these tests is a great way to learn more about care and treatment. Consider asking the questions below before and after the test.
Questions to ask before a blood test:
Questions to ask after a blood test:
A CBC is one of the most common blood tests. It measures the main components of the patient's blood.
A CBC test may be used to diagnose some blood cancers, such as leukemia, but it isn't typically used to diagnose solid tumor cancers, such as breast cancer or lung cancer.
It’s also common to have a CBC test after receiving a cancer diagnosis, to help the care team get a bigger picture of the patient's overall health.
A CBC test can help the care team:
White blood cells
These cells help the 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. The care team will pay close attention to the patient's neutrophil level. Low levels of neutrophils may mean he or she is at higher risk of an infection.
Red blood cells
These cells carry oxygen to cells throughout the body, and they carry carbon dioxide away. 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 the patient to feel tired and lack energy. High levels may indicate dehydration.
Platelets
Platelet cells help the blood clot, which helps control bruising and bleeding when the patient has a wound or injury. The patient's platelet count can help his or her care team know if he or she is 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.
The normal ranges below are measured in cells per microliter (mcL).
| CBC blood test component | Women | Men |
|---|---|---|
| White blood cells (WBC) | 4,500 to 10,000 cells/mcL | 4,500 to 10,000 cells/mcL |
| Red blood cells (RBC) | 4.2 to 5.4 million cells/mcL | 4.7 to 6.1 million cells/mcL |
| Hemoglobin (Hgb) | 12.1 to 15.1 gm/dL | 13.8 to 17.2 gm/dL |
| Hematocrit (Hct) | 36.1% to 44.3% | 40.7% to 50.3% |
| Platelets (Plt) | 150,000 to 450,000/dl | 150,000 to 450,000/dl |
Keep in mind that there are many reasons why certain levels could be abnormal. Factors such as recent diet and activity may affect the results. The patient's cancer care team can help him or her understand the results, catch things early and avoid complications.
A CBC with differential measures the components above, as well as assessing each type of white blood cell. The cancer care team may order these tests to track the status of the patient’s disease, evaluate what may be causing specific symptoms (such as fatigue or bruising) or to monitor the patient’s overall health.
A comprehensive metabolic panel—also called a blood chemistry panel—is another type of blood test that measures 14 different substances in the blood. This test can help the care team get information about the patient's metabolism, or how his or her body is using food and spending energy.
A CMP measures substances like:
The care team may use a CMP to see how the patient's body is responding to treatment. Some treatments can change the level of certain substances in the blood.
Some side effects from cancer treatment—like vomiting and diarrhea—may cause the patient to be dehydrated, which can affect blood chemistry, too. The patient won’t feel these changes in his or her blood chemistry level until it’s a bigger problem.
A CMP measures many different substances, and each one tells the care team something different about the patient's body. The care team may monitor electrolytes, for example, to see how the patient is handling treatments and to make sure he or she isn't dehydrated. They may monitor certain waste products to see how well the patient's kidneys or liver are working. And they may look at enzyme and protein results to see how the patient's liver is functioning.
Check with the care team, as the patient may need to fast before having a CMP.
The 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, are as follows, measured in grams (g), milligrams (mg), micrograms (U) and milliequivalents (mEq) per liter (L) or deciliter (dL).
| CMP blood test component | Normal range |
|---|---|
| Albumin, liver protein | 3.4 to 5.4 g/dL |
| ALP (alkaline phosphatase), liver enzyme | 20 to 130 U/L |
| ALT (alanine aminotransferase), liver enzyme | 4 to 36 U/L |
| AST (aspartate aminotransferase), liver enzyme | 8 to 33 U/L |
| BUN (blood urea nitrogen), kidney waste product | 6 to 20 mg/dL |
| Calcium, mineral | 8.5 to 10.2 mg/dL |
| Chloride, electrolyte | 96 to 106 mEq/L |
| CO2 (carbon dioxide), electrolyte | 23 to 29 mEq/L |
| Creatinine, kidney waste product | 0.6 to 1.3 mg/dL |
| Glucose, sugar | 70 to 100 mg/dL |
| Potassium, electrolyte | 3.7 to 5.2 mEq/L |
| Sodium, electrolyte | 135 to 145 mEq/L |
| Total bilirubin, liver waste product | 0.1 to 1.2 mg/dL |
| Total protein, blood protein | 6.0 to 8.3 g/dL |
The timing of blood test results depend on the specific test the care team ordered and where testing was performed, but results are typically available within three to five days following the blood draw.
In some cases, the provider who ordered the test will call the patient with the results or set up a follow-up appointment to discuss them, while in other instances, the results may show up in the patient’s health care online portal as soon as they’re ready. Talk to the care team about when to expect blood test results.