I. Introduction

Although many conditions can cause an abnormal CBC result, cancer, bone marrow disorders, and anemia are among the most common. According to the National Cancer Institute, there are just under 440 new cases of cancer per year for every 100,000 Americans. This amounts to more than 1.3 million new cases of cancer each year. Approximately 61,780 new cases of leukemia are diagnosed annually. Leukemia is a type of cancer involving the bone marrow. Anemia affects approximately 5.6% of the U.S. population.

This guide provides a detailed overview of the complete blood count, including what it measures, why it’s ordered, and how it can help in the diagnosis and management of cancer, bone marrow disorders, and anemia.

II. Overview of the Complete Blood Count

Why should I get tested?

The purpose of the complete blood count is to measure several components of the blood. Any abnormalities can indicate the presence of cancer, a problem with the bone marrow, or an underlying condition such as anemia or an autoimmune disease.

When should I get tested?

Medical professionals typically order the CBC as part of a routine checkup for adults. According to the American Academy of Family Physicians, the CBC should also be ordered under the following circumstances:

  • When an individual is losing weight without trying and there is no obvious cause of the weight loss
  • When an individual has an ongoing fever or other signs of infection
  • When an individual is weak, bruises easily, or has any other signs of cancer

What is required for the test?

Laboratory personnel need to analyze a sample of blood to determine if there are any abnormalities.

What do I need to do to prepare for the test?

The CBC itself doesn’t require any special preparation, however, blood for the CBC is often drawn at the same time as blood that will be used for other tests. Some of these tests are affected by medications, certain foods and beverages, strenuous exercise, or tobacco use. Therefore, an individual scheduled for more than one blood test should ask ahead of time if it’s necessary to fast overnight or stop taking any medications several days before the blood draw.

III. The Basics of Cancer, Bone Marrow Disorders, and Anemia

Cancer

Cancer is not a single disease. It’s a group of related diseases that can start in almost any type of tissue. Several factors contribute to an individual’s risk of developing cancer, but all cancers have the same basic cause: a disruption in the process of destroying old cells and replacing them with new ones. Cancer develops when damaged cells aren’t destroyed and new cells are generated even though they’re not needed. The cells continue to divide, which may cause tumors to form. Left untreated, cancer can spread into the surrounding tissues. Pieces of a tumor can also break off and travel to other parts of the body, forming brand-new tumors.

Several factors increase a person’s risk of developing cancer; some of these risk factors are controllable, while others are not. Controllable risk factors include alcohol use, dietary habits, exposure to harmful chemicals, obesity, exposure to sunlight, tobacco use, and the use of medications that suppress the immune system. Uncontrollable risk factors, or risk factors that can’t be altered, including age, hormones, and exposure to infectious organisms.

Cancer can affect almost any part of the body, so it causes a wide range of symptoms.

  • Nervous system: Seizures, headaches, double vision, blurred vision, hearing loss, facial drooping
  • Skin: Slow-healing sores, new moles, yellowing of the skin, scaly lumps, yellowing of the whites of the eyes
  • Mouth: Red or white patches on the tongue, pain in the mouth, bleeding in the mouth, numbness of the mouth, red or white patches in the mouth
  • GI system: Bloody stools, constipation or diarrhea, abdominal pain, nausea, vomiting, difficulty swallowing, frequent indigestion, changes in appetite
  • Urinary system: Bloody urine, painful urination, trouble urinating
  • Breasts: Nipple discharge, lumps in the breast, puckered skin on the breast, dimples in the breast

Cancer may also cause general symptoms such as fatigue, weakness, easy bruising, and bleeding with no known cause.

Bone Marrow Disorders

The bone marrow produces stem cells, which are capable of turning into other types of cells. Stem cells are the precursors to red blood cells, white blood cells, and platelets, making them essential for survival. In people with bone marrow disorders, the bone marrow does not produce enough stem cells, or the stem cells it produces are abnormal in some way. Although there are several types of bone marrow disorders, leukemia is one of the most common. Leukemia occurs when the bone marrow produces abnormal white blood cells. This condition is classified as a blood cancer, but it’s also a bone marrow disorder because of its effects on cell production.

Leukemia is classified according to cell type as well as how long it takes to develop. Acute leukemia progresses quickly, while chronic leukemia may not cause symptoms for several years. Myelogenous leukemia develops from the myeloid cell line; cells in this line are supposed to turn into white blood cells, red blood cells, and platelets. Lymphocytic leukemia develops from the lymphoid cell line; cells in this line are supposed to turn into white blood cells. Leukemia can be classified as acute myeloid leukemia, chronic myelogenous leukemia, acute lymphocytic leukemia, or chronic lymphocytic leukemia.

The symptoms of leukemia vary by type, but common symptoms include fatigue, pale skin, easy bruising, lack of energy, unexplained weight loss, weakness, easy bleeding, fevers of unknown origin, joint pain, swollen lymph nodes, and night sweats. Leukemia develops due to a mutation in an individual’s DNA. The exact cause of this mutation is unknown, but it may be caused by using tobacco, working with toxic chemicals, having radiation therapy to treat another type of cancer, or having a genetic disorder.

Anemia

In people with anemia, the organs and tissues do not get enough oxygenated blood. One of the most common causes of anemia is iron deficiency, which can occur when people do not eat enough iron-rich foods. Iron-deficiency anemia can also develop in women who have heavy menstrual periods, people who donate blood frequently, and people who take medications that interfere with iron absorption. Anemia may also develop as a result of an underlying medical condition. Kidney disease, infections, and cancer all increase the risk of anemia.

Because the organs and tissues do not get enough oxygen, people with anemia tend to feel weak and fatigued. They may also have pale skin, headaches, or dizziness.

IV. How a Complete Blood Count Works

To perform a CBC, laboratory personnel use the Beckman Coulter method for counting particles. This method involves taking a sample of blood and passing it through a small opening at the same time an electrical current is moving through the opening. A machine counts the particles in the blood at a rate of several thousand per second, making it possible to quickly determine how many red blood cells, white blood cells, and platelets are in a blood sample.

In addition to counting the number of red blood cells, white blood cells, and platelets in a blood sample, laboratory personnel calculate parameters such as hematocrit and hemoglobin concentration. Hematocrit is a measurement of how much of a person’s blood is composed of red blood cells, while hemoglobin concentration is a measurement of the amount of hemoglobin in the blood. Hemoglobin is a protein that transports oxygen throughout the body. Both measurements are useful for determining if an individual has anemia.

V. Treatment for Cancer, Bone Marrow Disorders, and Anemia

Cancer

A cancer treatment plan should be customized based on the type of cancer an individual has, the individual’s health history, and the stage of the cancer. A treatment that is effective for early-stage breast cancer may not be appropriate for treating late-stage lung cancer, so it’s important for an individual with cancer to see an oncologist (cancer specialist) regularly. Some of the most common treatment methods include surgery, radiation, chemotherapy, targeted therapy, immunotherapy, hormone therapy, precision medicine, and stem cell transplant.

During surgery to treat cancer, a surgeon cuts into the body to remove cancerous growths. The surgeon may also remove healthy-looking tissue and lymph nodes so that they can be analyzed to determine if the cancer has spread. Radiation therapy uses high-dose radiation to shrink tumors and destroy cancerous cells. The radiation destroys the DNA inside the cancer cells, causing the cells to die and preventing them from continuing to multiply. Chemotherapy also kills cancer cells, but it involves the use of drugs instead of radiation. Chemotherapy can shrink tumors or even cause cancer to go into remission.

Targeted therapy targets whatever is in the cancer cells that makes them multiply so rapidly. Small-molecule drugs are used for targets located within the cells, while monoclonal antibodies are used for targets that are on the surface of the cells. Immunotherapy uses substances derived from living organisms to help the immune system fight cancer. Some forms of immunotherapy make T-cells stronger; T-cells are white blood cells involved in the immune response. Other forms of immunotherapy help the immune system get around the natural defense system of a tumor.

Some cancers are fueled by hormones; hormone therapy is used to treat these cancers. This type of treatment can be used to relieve cancer symptoms, slow the growth of cancer, or prevent cancer from returning once it’s in remission. Precision medicine involves using an individual’s genetic information to develop a treatment plan that’s more likely to be effective. This type of treatment is not yet available to everyone with cancer, but researchers are working to make it available to more people. Stem cell transplants are used to replace stem cells in people who have had radiation therapy or taken high doses of chemotherapy drugs. This type of treatment helps the bone marrow produce normal blood cells

Bone Marrow Disorders

Because leukemia is a blood cancer, it’s often treated with chemotherapy, radiation therapy, and/or stem cell transplant. The treatment plan depends on which type of leukemia an individual has. For example, the treatment for acute myelogenous leukemia usually occurs in two phases. During the first phase, the aim of treatment is to cause the cancer to go into remission. This is accomplished by killing the cancerous cells in the blood and bone marrow. During the second phase, the aim of treatment is to destroy any lingering leukemia cells so that they can’t become active again. This phase is known as post-remission therapy or remission continuation therapy.

Anemia

The right treatment for anemia depends on the underlying cause. For people with iron-deficiency anemia caused by a lack of iron intake, eating iron-rich foods and taking iron supplements can cure the condition. If anemia is caused by blood loss, then it’s important to find and treat the underlying cause. For example, a medical professional may order tests to determine if there is bleeding in the gastrointestinal system. Anemia associated with chronic diseases may be treated with injections of erythropoietin, a substance that stimulates the bone marrow to produce more red blood cells. Since the red blood cells contain hemoglobin, the protein that transports oxygen, this can relieve symptoms of anemia.

VI. FAQs

What is the difference between a CBC and a CBC with differential?

The main difference between the CBC and the CBC with differential is the amount of information provided. The CBC includes the total number of white blood cells, the total number of red blood cells, the total number of platelets, the hemoglobin level, and the hematocrit calculation. A CBC with differential provides the same information, but it also includes a breakdown of the five different types of white blood cells: basophils, neutrophils, eosinophils, monocytes, and lymphocytes. The extra information can be helpful for diagnosing cancer, infections, and inflammatory diseases.

What is a normal level of red blood cells?

Normal results vary for men and women. In men, a normal red blood cell count ranges from 4.7 to 6.1 million cells per microliter of blood. The normal range in women is 4.2 to 5.4 million cells per microliter of blood.

What is a normal level of white blood cells?

A normal white blood cell count ranges from 4,500 to 11,000 white blood cells per microliter of blood.

What is a normal level of platelets?

A normal platelet count ranges from 150,000 to 400,000 platelets per microliter of blood.

What is a normal hemoglobin level?

In adult men, a normal hemoglobin level ranges from 13.8 to 17.2 grams of hemoglobin per deciliter of blood. The normal level for adult women is between 12.1 and 15.1 grams of hemoglobin per deciliter of blood.

What is a normal hematocrit?

Hematocrit results are expressed as percentages. In adult men, a normal hematocrit ranges from 40.7% to 50.3%; in adult women, it ranges from 36.1% to 44.3%.

VII. Additional Resources

NameWebsiteSummary
National Cancer Institutewww.cancer.govThe NCI explains how cancer develops and what happens when it spreads.
MDS Foundationwww.mds-foundation.orgLearn more about myelodysplastic syndromes, which cause a lack of healthy blood cells.
American Society of Hematologywww.hematology.orgThe ASH offers more information about anemia, including why it occurs and what symptoms it causes.
Healthlinewww.healthline.comLearn how to reduce the risk of iron-deficiency anemia by eating iron-rich foods.
American Cancer Societywww.cancer.orgThe American Cancer Society describes some of the tests commonly used to diagnose cancer and monitor individuals undergoing cancer treatment.

VIII. Sources Used in This Article

  1. https://www.cancer.gov/about-cancer/understanding/statistics. Accessed December 2019.
  2. https://seer.cancer.gov/statfacts/html/leuks.html. Accessed December 2019.
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5112924/. Accessed December 2019.
  4. https://medlineplus.gov/lab-tests/complete-blood-count-cbc/. Accessed December 2019.
  5. https://familydoctor.org/complete-blood-count-cbc/. Accessed December 2019.
  6. https://www.cancer.gov/about-cancer/diagnosis-staging/symptoms. Accessed December 2019.
  7. https://medlineplus.gov/bonemarrowdiseases.html. Accessed December 2019.
  8. https://www.nhlbi.nih.gov/health-topics/anemia. Accessed December 2019.
  9. https://www.cdc.gov/nchs/data/nhanes/nhanes_03_04/l25_c_met_complete_blood_count.pdf. Accessed December 2019.
  10. https://medlineplus.gov/lab-tests/hematocrit-test/. Accessed December 2019.
  11. https://www.ncbi.nlm.nih.gov/books/NBK259/. Accessed December 2019.
  12. https://www.cancer.gov/about-cancer/treatment/types. Accessed December 2019.
  13. https://www.cancer.gov/about-cancer/treatment/types/surgery. Accessed December 2019.
  14. https://www.cancer.gov/about-cancer/treatment/types/chemotherapy. Accessed December 2019.
  15. https://www.cancer.gov/about-cancer/treatment/types/hormone-therapy. Accessed December 2019.
  16. https://www.cancer.gov/about-cancer/treatment/types/precision-medicine. Accessed December 2019.
  17. https://www.cancer.gov/about-cancer/treatment/types/stem-cell-transplant. Accessed December 2019.
  18. https://www.hematology.org/Education/Patients/Anemia/. Accessed December 2019.
  19. https://medlineplus.gov/ency/article/003644.htm. Accessed December 2019.
  20. https://medlineplus.gov/ency/article/003643.htm. Accessed December 2019.
  21. https://medlineplus.gov/ency/article/003647.htm. Accessed December 2019.
  22. https://medlineplus.gov/ency/article/003645.htm. Accessed December 2019.
  23. https://medlineplus.gov/ency/article/003646.htm. Accessed December 2019.