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Diagnosis and tests

How CML is diagnosed

The related article (“CML: symptoms, phases and diagnosis”) explains bone marrow aspiration. This topic shows the path to a CML diagnosis, from the blood count to defining the phase and the baseline PCR level.

Last updated: ~1 min read
Cells at every stage.
Figure 1.The CML cell spectrum.

01Short answer

CML is often found because of a very high white count on a blood test. The smear shows myeloid cells at every stage of maturity, from immature to mature, often with raised basophils; platelets may be high. The doctor checks the size of the spleen. The diagnosis is confirmed by finding the Philadelphia chromosome or the BCR::ABL1 fusion, which can be done on blood with FISH or PCR. A bone marrow aspiration and karyotype are usually done at diagnosis: they show the phase (the blast percentage) and any additional chromosome changes. Quantitative PCR sets the baseline BCR::ABL1 level and the transcript type, which later monitoring builds on. Risk scores (age, spleen size, blasts, basophils, platelets) help estimate the outlook.

02Simple explanation

A high white count: often the first sign.

BCR::ABL1: confirmation.

Phase and baseline: marrow and PCR.

03Scientific explanation

Risk scores: scores such as Sokal or ELTS combine age, spleen size, blasts and platelets.

Transcript type: e13a2, e14a2 or rarer types are identified at diagnosis so that qPCR monitoring is set up correctly.

04What happens in the body?

A spectrum of cells

A CML smear shows cells at every stage of maturity.

A PCR baseline

The starting BCR::ABL1 level is the basis for later monitoring.

A PCR curve on a calendar.
Figure 2.A PCR baseline — How CML is diagnosed

Assessing the phase

The marrow test shows which phase the disease is in.

A three-step scale — How CML is diagnosed
Figure 3.Assessing the phase.

05Diagnosing CML

Four steps.

Blood — A high white count.1BloodA high white count.
Spleen — Examination.2SpleenExamination.
Marrow — Karyotype, phase.3MarrowKaryotype, phase.
PCR — Baseline level.4PCRBaseline level.

06Tests in diagnosing CML

TestPurpose
Blood count, smearHigh white count, basophils
Physical examinationSpleen size
Marrow aspiration, karyotypePhase, additional changes
FISHConfirms BCR::ABL1
Quantitative PCRBaseline level, transcript type

07Key terms

CML
Chronic myeloid leukaemia.
Basophilia
Raised basophils.
Transcript
The RNA form of BCR::ABL1.
Risk score
A calculation used for outlook.
Baseline
A measurement before treatment.

08Key points

  • CML is often found on a blood test.
  • BCR::ABL1 confirms the diagnosis.
  • The marrow shows the phase.
  • A baseline PCR matters.
  • Risk scores help with outlook.
  • PCR monitoring is regular.

09Frequently asked questions

Is a marrow test essential?

It is usually recommended at diagnosis because it shows the phase and additional changes.

Why does the transcript type matter?

To choose the right PCR test.

How often will I have PCR?

More often at the start of treatment, then less often; your doctor sets the plan.

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. Is a marrow test essential?

  2. Why does the transcript type matter?

  3. How often will I have PCR?

My questions

12Sources

  1. National Cancer Institute (NCI). CML treatment (PDQ), patient version
  2. National Cancer Institute (NCI). Definition: Philadelphia chromosome
  3. National Cancer Institute (NCI). Definition: polymerase chain reaction
  4. American Cancer Society. Infections in People with Cancer
  5. MedlinePlus (U.S. National Library of Medicine). Blood culture
  6. MedlinePlus (U.S. National Library of Medicine). Hepatitis Testing
  7. MedlinePlus (U.S. National Library of Medicine). HIV Screening Test
  8. MedlinePlus (U.S. National Library of Medicine). Cytomegalovirus (CMV) Tests
  9. MedlinePlus (U.S. National Library of Medicine). Chickenpox and Shingles Tests
  10. MedlinePlus (U.S. National Library of Medicine). Respiratory Pathogens Panel
Medical disclaimerThis information is for educational purposes only and does not replace medical advice.
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