Low blood cell counts: Side effect of cancer treatment

Low blood cell counts can be a serious complication during cancer treatment. Know why your doctor closely tracks your blood cell counts.

By Mayo Clinic Staff

Your doctor may monitor your blood cell counts carefully during your cancer treatment. There's a good reason you're having your blood drawn so often — low blood cell counts put you at risk of serious complications.

What's measured in a blood cell count?

If you're undergoing certain cancer treatments that could cause low blood cell counts, your doctor will likely monitor your blood cell counts regularly using a test called a complete blood count with differential (CBC w/diff). Low blood cell counts are detected by examining a blood sample taken from a vein in your arm.

When checking your blood cell count, your doctor is looking at the numbers and types of the following:

  • White blood cells. White blood cells help your body fight infection. The CBC w/diff test measures the levels of five types of white blood cells in your blood. Your doctor will pay close attention to the levels of neutrophils, which are particularly helpful for fighting infections caused by bacteria. A low neutrophil count (neutropenia) leaves your body more open to infection. And if an infection does develop, your body may be unable to fight it off.
  • Red blood cells. Red blood cells carry oxygen throughout your body. Your red blood cells' ability to carry oxygen is measured by the amount of hemoglobin in your blood. If your level of hemoglobin is low, you're anemic and your body works much harder to supply oxygen to your tissues. This can make you feel fatigued and short of breath.
  • Platelets. Platelets help your blood to clot. A low platelet count (thrombocytopenia) means your body can't stop itself from bleeding.
What's being counted What's normal for adults What may be concerning
Neutrophils 1,560 to 6,450 Below 1,000
Hemoglobin
  • 13.2 to 16.6 for males
  • 11.6 to 15 for females
Below 8
Platelets
  • 135,000 to 317,000 for males
  • 157,000 to 371,000 for females
Below 50,000

What causes low blood cell counts?

Common cancer-related causes of low blood cell counts include:

  • Chemotherapy. Certain chemotherapy drugs can damage your bone marrow — the spongy material found in your bones. Your bone marrow makes blood cells, which grow rapidly, making them very sensitive to the effects of chemotherapy. Chemotherapy kills many of the cells in your bone marrow, but the cells recover with time. Your doctor can tell you whether your specific chemotherapy treatment and dose will put you at risk of low blood cell counts.
  • Radiation therapy. If you receive radiation therapy to large areas of your body and especially to the large bones that contain the most bone marrow, such as your pelvis, legs and torso, you might experience low levels of red and white blood cells.
  • Cancers of the blood and bone marrow. Blood and bone marrow cancers, such as leukemia, grow in the bone marrow and don't allow normal blood cells to develop.
  • Cancers that spread (metastasize). Cancer cells that break off from a tumor can spread to other parts of your body, including your bone marrow. The cancerous cells can displace other cells in your bone marrow, making it difficult for your bone marrow to produce the blood cells your body needs.

What are the complications of low blood cell counts?

Low blood cell counts may delay your next round of treatment or lead your doctor to reduce medication dosage or prescribe a new medication. Monitoring your blood cell counts allows your doctor to prevent or reduce your risk of complications.

The most serious complications of low blood cell counts include:

  • Infection. With a low white blood cell count and, in particular, a low level of neutrophils, you're at higher risk of developing an infection. And if you develop an infection when you have a low white blood cell count, your body can't protect itself. Infection can lead to death in severe cases.

    Even a mild infection can delay your chemotherapy treatment, since your doctor may wait until your infection is cleared and your blood cell counts go back up before you continue. Your doctor may also recommend medication to increase your body's production of white blood cells.

  • Anemia. A low red blood cell count is anemia. The most common symptoms of anemia are fatigue and shortness of breath. In some cases, fatigue becomes so severe that you must temporarily halt your cancer treatment or reduce the dose you receive. While mild anemia is common and often does not cause fatigue, tell your doctor if you are having these symptoms to see if anemia is a possible cause.

    Anemia can be relieved with a blood transfusion or with medication to increase your body's production of red blood cells.

  • Bleeding. Low numbers of platelets in your blood can cause bleeding. You might bleed excessively from a small cut or bleed spontaneously from your nose or gums. Rarely, dangerous internal bleeding can occur.

    A low platelet count can delay your treatment. You may have to wait until your platelet levels go up in order to continue with chemotherapy or to have surgery. A low platelet count can also be treated with a platelet transfusion.

How can you tell if you have low blood cell counts?

Unless your blood cell counts are very low, you probably won't experience any signs or symptoms and you won't be able to tell that your blood cell counts are down. That's why your doctor may order frequent blood tests to follow your blood cell counts.

Ask your doctor whether your cancer treatment is likely to cause low blood cell counts and what signs and symptoms you should be looking for. If you notice any signs or symptoms of low blood cell counts, tell your doctor right away.

Condition What to look for
Source: National Cancer Institute, 2018
Low white blood cell count
  • Fever higher than 100.5 F (38 C)
  • Chills
  • Sweating
Low red blood cell count
  • Fatigue
  • Chest pain
  • Dizziness
  • Shortness of breath
Low platelet count
  • Bleeding
  • Easy bruising
  • Heavy menstrual bleeding

How can you cope with low blood cell counts?

Take steps to keep your body healthy when you have low blood cell counts. For example:

  • Eat a balanced diet. Your body needs all the vitamins and nutrients it can get to heal itself during and after your treatment. Choose plenty of fruits and vegetables. If treatment complications make eating difficult — for example, if you experience nausea and vomiting or mouth sores — experiment to find foods you can tolerate.
  • Avoid injury. Many everyday activities put you at risk of cuts and scrapes. A low platelet count makes even minor abrasions serious. A low white blood cell count can turn a small cut into a starting point for a serious infection. Use an electric shaver rather than a razor to avoid nicks. Ask someone else to cut up food in the kitchen. Be gentle when brushing your teeth and blowing your nose.
  • Avoid germs. Avoid unnecessary exposure to germs when you can. Wash your hands frequently or use a liquid hand sanitizer. Avoid people who are sick and stay away from crowds. Have someone else clean the litter box, bird cage or fish tank. Don't eat raw meat or eggs.

Talk to your health care team about other ways you can cope with low blood cell counts.

Get the latest health information from Mayo Clinic’s experts.

Sign up for free, and stay up to date on research advancements, health tips and current health topics, like COVID-19, plus expertise on managing health.

To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.

Jan. 09, 2021 See more In-depth

See also

  1. Adjuvant therapy for cancer
  2. After a flood, are food and medicines safe to use?
  3. Alternative cancer treatments: 10 options to consider
  4. Atypical cells: Are they cancer?
  5. Biological therapy for cancer
  6. Biopsy procedures
  7. Blood Basics
  8. Bone marrow transplant
  9. Bone scan
  10. Cancer
  11. Cancer blood tests
  12. Myths about cancer causes
  13. Infographic: Cancer Clinical Trials Offer Many Benefits
  14. Cancer diagnosis: 11 tips for coping
  15. Cancer diagnosis? Advice for dealing with what comes next
  16. Cancer-related fatigue
  17. Cancer pain: Relief is possible
  18. Cancer-prevention strategies
  19. Cancer risk: What the numbers mean
  20. Cancer surgery
  21. Cancer survival rate
  22. Cancer survivors: Care for your body after treatment
  23. Cancer survivors: Late effects of cancer treatment
  24. Cancer survivors: Managing your emotions after cancer treatment
  25. Cancer survivors: Reconnecting with loved ones after treatment
  26. Cancer treatment decisions: 5 steps to help you decide
  27. Cancer treatment for men: Possible sexual side effects
  28. Cancer treatment for women: Possible sexual side effects
  29. Cancer treatment myths
  30. Cancer Vaccine Research
  31. Cellphones and cancer
  32. Chemo Targets
  33. Chemoembolization
  34. Chemotherapy
  35. Chemotherapy and hair loss: What to expect during treatment
  36. Chemotherapy and sex: Is sexual activity OK during treatment?
  37. Chemotherapy nausea and vomiting: Prevention is best defense
  38. Chemotherapy side effects: A cause of heart disease?
  39. Complete blood count (CBC)
  40. Cough
  41. CT scan
  42. CT scans: Are they safe?
  43. Curcumin: Can it slow cancer growth?
  44. Cancer-related diarrhea
  45. Eating during cancer treatment: Tips to make food tastier
  46. Fatigue
  47. Fertility preservation
  48. Get ready for possible side effects of chemotherapy
  49. Ginger for nausea: Does it work?
  50. Heart cancer: Is there such a thing?
  51. High-dose vitamin C: Can it kill cancer cells?
  52. Honey: An effective cough remedy?
  53. How plant-based food helps fight cancer
  54. Infographic: CAR-T Cell Therapy
  55. Intrathecal chemotherapy
  56. Joint pain
  57. Joint pain: Rheumatoid arthritis or parvovirus?
  58. Magic mouthwash
  59. Medical marijuana
  60. Mediterranean diet recipes
  61. Mindfulness exercises
  62. Minimally invasive cancer surgery
  63. Monoclonal antibody drugs
  64. Mort Crim and Cancer
  65. Mouth sores caused by cancer treatment: How to cope
  66. MRI
  67. Muscle pain
  68. Night sweats
  69. No appetite? How to get nutrition during cancer treatment
  70. Palliative care
  71. PALS (Pets Are Loving Support)
  72. Pelvic exenteration
  73. PET/MRI scan
  74. Pet therapy
  75. Radiation therapy
  76. Infographic: Scalp Cooling Therapy for Cancer
  77. Secondhand smoke
  78. Seeing inside the heart with MRI
  79. Self-Image During Cancer
  80. Sentinel lymph node mapping
  81. Sisters' Bone Marrow Transplant
  82. Sleep tips
  83. Mediterranean diet
  84. Radiation simulation
  85. Small cell, large cell cancer: What this means
  86. Stem Cells 101
  87. Stem cells: What they are and what they do
  88. Thalidomide: Research advances in cancer and other conditions
  89. Treating pain: When is an opioid the right choice?
  90. Tumor vs. cyst: What's the difference?
  91. TVEC (Talimogene laherparepvec) injection
  92. Ultrasound
  93. Unexplained weight loss
  94. Stem cell transplant
  95. How cancer spreads
  96. MRI
  97. PICC line placement
  98. Compassionate use
  99. When cancer returns: How to cope with cancer recurrence
  100. Wide local skin excision
  101. X-ray
  102. Your secret weapon during cancer treatment? Exercise!