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After treatment and remission

Monitoring with the CBC

In remission, the simplest and most frequent test is the complete blood count. It is a “window” onto how the bone marrow is working. This topic explains what your doctor looks for in a blood count during follow-up, which changes are common and which call for a closer look.

Last updated: ~4 min read
White cells, red cells and platelets
Figure 1.White cells, red cells and platelets — a blood count reflects how the bone marrow is working.

01Short answer

A complete blood count (CBC) measures white cells and their types (the differential), neutrophils, haemoglobin and platelets. In remission it confirms that the bone marrow is working normally and helps spot early signs of relapse — such as unexplained falls in counts or blasts appearing in the blood. After acute leukaemia it is usually done monthly or more often at first, then less often. Counts often sit near the lower limit of normal for a while after treatment. Your doctor looks at the trend rather than a single number: if something changes, the test is repeated and, if needed, a blood film, bone marrow test or MRD test follows. Always interpret results with your doctor.

02Simple explanation

A blood count is like the bone marrow’s “report”: what the marrow makes shows up in the blood.

There are four main values: white cells, neutrophils, haemoglobin and platelets.

The differential shows the types of white cell and helps check that there are no immature cells (blasts) in the blood.

After treatment, counts may stay near the lower limit of normal for a while — often this is simply recovery.

What matters is the trend, not a single result: are counts stable, rising or falling?

03Scientific explanation

How often: according to the ACS, after AML check-ups are about monthly at first, then less frequent, and continue for at least several years; a blood count is usually done at each visit.

Remission criteria: ELN 2022 defines complete remission as neutrophils above 1.0×10⁹/L, platelets above 100×10⁹/L and no blasts in the blood.

Differential: according to MedlinePlus, the white cell differential measures the five main types — neutrophils, lymphocytes, monocytes, eosinophils and basophils — and helps detect abnormal or immature cells.

Reference ranges: normal limits vary with age, sex and laboratory, so a result should be compared with that laboratory’s own range.

04What happens in the body?

What does the doctor look at?

White cells reflect protection against infection, and neutrophils are its main part. Haemoglobin reflects oxygen transport, and platelets reflect clotting. The differential shows the types of white cell and makes it possible to check whether blasts have appeared in the blood. Together they give an overall picture of how the marrow is working.

Which changes can be normal?

In the months after treatment, neutrophils or platelets are often slightly below normal. A viral infection, some medicines, or a lack of iron or vitamins can also change counts temporarily. After a transplant, some medicines and viruses can lower blood counts.

Which changes need attention?

A fall that persists over several tests with no clear cause; blasts appearing in the blood; a sharp rise in white cells; changes that come with symptoms — fever, bruising, bone pain. In these cases your doctor may repeat the test, look at a blood film or arrange a bone marrow test.

On a dark navy background, a blood film on a glass slide under a magnifying lens, with healthy-looking blood cells inside the lens.
Figure 3.If something changes, your doctor may look at a blood film under the microscope.

The follow-up schedule

After acute leukaemia, blood counts are usually checked monthly or more often at first, then every 2–3 months and less often. In ALL, tests are more frequent during maintenance, because medicine doses are adjusted according to blood counts. Your team sets the exact schedule.

On a dark navy background, a row of clear blood sample tubes along a timeline, linked by a soft line of light.
Figure 2.Tests from each visit form a line — your doctor looks at this trend.

Keeping track of results

After each test, write the main numbers in your own table or keep copies of the results. Use the same laboratory where possible. Do not try to draw conclusions from the numbers yourself — if you have a question, ask it at your next visit or by phone.

05From blood test to decision

Not one number, but the whole picture.

Test — Complete blood count and differential.1TestComplete blood count and differential.
Comparison — The trend against earlier results.2ComparisonThe trend against earlier results.
Repeat if needed — Repeat test, blood film.3Repeat if neededRepeat test, blood film.
Decision — Follow-up continues, or further tests.4DecisionFollow-up continues, or further tests.
The trend is visibleChanges are caught in time.
ReassuranceStable results support remission.
An early stepFurther tests when they are needed.

06The main values in a blood count (simplified)

ValueWhat it reflectsWhat follow-up looks for
White cellsTotal number of immune cellsStability, a sharp rise or fall
NeutrophilsMain defence against bacteriaInfection risk, marrow recovery
Differential, blastsTypes of white cellNo immature cells in the blood
HaemoglobinOxygen transportWhether there is anaemia, the trend
PlateletsBlood clottingUnexplained falls, bleeding risk
MCVAverage size of red cellsA trace of some medicines and deficiencies

* Normal ranges differ between laboratories. Your doctor will explain what your results mean in the light of your history.

07Key terms

Complete blood count (CBC)
The basic test that counts blood cells.
Differential
The breakdown of white cells by type.
Absolute neutrophil count (ANC)
The actual number of neutrophils in the blood.
Blast
An immature blood cell; normally absent from the blood.
Cytopenia
A fall in one or more blood counts.
Reference range
The limits a laboratory considers normal.
Blood film
A drop of blood examined under the microscope.
Trend
The direction in which results change over time.

08Key points

  • The blood count is the main monitoring tool in remission.
  • Four main values: white cells, neutrophils, haemoglobin, platelets.
  • The differential helps check the blood for blasts.
  • Mild falls after treatment can be normal.
  • Look at the trend, not a single number.
  • If something changes, the test is repeated.
  • Keep your results in a table.
  • If you have symptoms, do not wait for the planned test.

09Frequently asked questions

If my blood count is normal, does that mean no relapse?

A normal count is a good sign, but it does not always show a very early relapse. That is why MRD or bone marrow tests are also done in some cases.

My neutrophils are slightly below normal. Should I worry?

This is common after treatment. Your doctor will look at the trend and how you are overall.

Do I need to fast before the test?

Usually not for a blood count. If biochemistry tests are taken at the same time, check with your doctor.

Can I compare my results with normal ranges online?

It is better to compare them with your own laboratory’s range, because normal ranges differ.

How long will I keep having blood counts?

Usually for several years, gradually less often. Your doctor will set the exact length.

Can a cold change my counts?

Yes, viral infections can temporarily change white cells and platelets. Tell your doctor you have been unwell.

10Questions for your doctor

Take these questions to your appointment. The ones you save are collected on the “My questions” page and stay on this device only.

  1. If my blood count is normal, does that mean no relapse?

  2. My neutrophils are slightly below normal. Should I worry?

  3. Do I need to fast before the test?

  4. Can I compare my results with normal ranges online?

  5. How long will I keep having blood counts?

  6. Can a cold change my counts?

My questions

12Sources

  1. MedlinePlus (U.S. National Library of Medicine). Complete Blood Count (CBC)
  2. MedlinePlus (U.S. National Library of Medicine). Blood Differential
  3. MedlinePlus (U.S. National Library of Medicine). Platelet Tests
  4. MedlinePlus (U.S. National Library of Medicine). Hemoglobin Test
  5. MedlinePlus (U.S. National Library of Medicine). White Blood Count (WBC)
  6. American Cancer Society. Living as an Acute Myeloid Leukemia (AML) Survivor
  7. American Cancer Society. Living as an Acute Lymphocytic Leukemia Survivor
  8. National Cancer Institute (NCI). Follow-Up Medical Care
  9. NHS. Blood tests
  10. Cancer Research UK. Your blood, bone marrow and cancer drugs
  11. National Heart, Lung, and Blood Institute (NHLBI). Thrombocytopenia
  12. Blood, 2022. Döhner H et al. Diagnosis and management of AML in adults: 2022 recommendations from an international expert panel on behalf of the ELN
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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