Healthy Living

How Is Leukemia Diagnosed?

How is Leukemia Diagnosed?

Key Takeaways

  • A person may overlook signs and symptoms of leukemia because a number of them are similar to those of common illnesses such as the flu.
  • A CBC determines the numbers of white blood cells, red blood cells, and platelets. In leukemia, these three components of the blood are highly affected and show abnormalities.
  • If the blood tests suggest leukemia, the doctor will look further for signs of the disease in the bone marrow before making a diagnosis.

Leukemia in its early stages may present no signs or symptoms, as these only appear when the leukemia cells have taken over a large number of normal blood cells. A person with leukemia is very lucky indeed if early-stage detection occurs incidentally, through a routine blood test or one done for some other condition.

The symptoms in chronic leukemia appear gradually, and usually start out mild in comparison with those of acute leukemia. And while the symptoms worsen over time, it may take as long as years after an initial diagnosis before they do. Thus, chronic leukemia is more often diagnosed as a result of a routine medical examination. 

The appearance of symptoms in acute leukemia, however, usually appear suddenly and worsen quickly. It is much more usual for someone with acute leukemia than one with chronic leukemia to see a doctor because of symptoms and be diagnosed with the disease because the symptoms. 

What are the signs and symptoms of leukemia?

A person may overlook signs and symptoms of leukemia because a number of them are similar to those of common illnesses such as the flu. It is important to see a doctor if symptoms persist, or worry you. The signs and symptoms of leukemia are the following:

  • Frequent fevers and infections - These occur because one's white blood cells are not functioning properly and so are unable to fight infection. 
  • Bleeding or bruising easily; heavy or recurrent nosebleeds - These happen possibly because the person does not have sufficient or healthy blood platelets, which are important in blood coagulation. 
  • Fatigue or weakness that persists - When there is a shortage of red blood cells, i.e., anemia, a person may feel tired and weak. 
  • A pale or washed-out appearance - This may be due to a lower number of red blood cells.
  • Tiny red spots in the skin (petachiae) - These pinpoint red spots appear when capillaries bleed and leak blood into the skin, usually due to a low platelet count, which happens in leukemia. 
  • Other possible symptoms are swollen lymph nodes (especially in the neck or armpit) or gums, an enlarged liver or spleen, bone or joint pain or tenderness, unexplained weight loss, and excessive sweating especially at night.  

How is leukemia diagnosed?

Generally, a doctor will ask about the medical history of the patient to identify the presence of any risk factors, do a physical examination to look for signs and symptoms, examine the patient's blood sample under a microscope for any abnormalities, and have blood tests and a bone marrow or lymph node biopsy done.

1. Medical History and Identification of Risk Factors

A detailed medical history is taken, and questions to determine whether any risk factors associated with the condition apply to the patient. 

Among the factors that increase one's risk of developing some types of leukemia are:

  • Previous cancer treatment - Having undergone chemotherapy or radiation therapy for other cancers increases a person's risk of developing certain types of leukemia.
  • Genetic disorders - Genetic abnormalities appear to play a role in the development of leukemia. Down syndrome, for instance, is associated with an increased risk of leukemia.
  • Family history of leukemia - With certain types of leukemia, having a first-degree relative or an identical twin who has or had one of those types may put one at a higher risk for that particular leukemia.
  • Exposure to certain chemicals - Prolonged exposure to certain pesticides and industrial chemicals is linked to an increased risk of some kinds of leukemia. 
  • Exposure to radiation - Exposure to high-energy radiation (e.g. a nuclear power plant meltdown) or intense exposure to low-energy radiation from electromagnetic fields (e.g. electricity lines) increases a person's risk for leukemia. 
  • Smoking - Smoking increases the risk of AML.

Notwithstanding the risk factors, most people laboring under any risk factor don't get leukemia, while many people who do get leukemia have none of these risk factors.

2. Physical Examination

During the physical examination, the doctor will check for pale skin, bleeding, bruises, lumps, swollen lymph nodes, and the enlargement of the liver and spleen. 

The patient's medical history, risk factors, and signs and symptoms may make a doctor suspect leukemia, but he or she will not make a diagnosis based on these alone. He or she will move further on and use blood tests, biopsies, and imaging studies before making a diagnosis. 

3. Blood Cell Exam (Peripheral Blood Smear)

A peripheral blood smear is used for all patients with suspected blood abnormalities. A drop of blood is smeared across a slide and looked at under a microscope to see the blood cells. Their appearance and the number of white blood cells (WBCs) relative to red blood cells (RBCs) help a doctor diagnose leukemia.

4. Blood Tests

A complete blood count, or CBC, is also used for all patients with suspected blood abnormalities. This is the first test done for the diagnosis of leukemia. A CBC determines the numbers of WBCs, RBCs, and platelets. In leukemia, these three components of the blood are highly affected and show abnormalities. A CBC performed with a differential can give key information that will help in diagnosing blood cancer such as: 

  • Blood count – A person with leukemia has an abnormally high WBC count and low platelet and RBC counts. 
  • Microscopic changes in the shape and size of the cells
  • Classification of leukemic cells based on proteins (immunophenotyping)
  • Classification of cancerous cells based on antibodies and cell components (immunohistochemistry)

5. Bone Marrow Aspiration and Biopsy

If the blood tests suggest leukemia, the doctor will look further for signs of the disease in the bone marrow before making a diagnosis. Bone marrow samples are obtained through bone marrow aspiration and biopsy, and both are often performed at the same time.

In bone marrow aspiration, a needle is inserted into a large bone, usually the hipbone, to obtain a small amount of marrow is removed. In bone marrow biopsy, a larger needle is used to collect bone marrow and a small piece of bone tissue. These samples can identify the type of leukemia the patient has as well as its growth rate. 

A pathologist (a doctor who specializes in lab tests) analyzes the samples based on the size, shape, and other characteristics of the white blood cells to classify the leukemia, based on whether it is acute or chronic, and myeloid or lymphocytic. 

There 4 main types of leukemia are:

  • Acute myeloid (or myelogenous) leukemia (AML)
  • Chronic myeloid (or myelogenous) leukemia (CML)
  • Acute lymphocytic (or lymphoblastic) leukemia (ALL)
  • Chronic lymphocytic leukemia (CLL)

Note that sometimes, an examination and analysis of the bone marrow cells still do not provide a definitive diagnosis, making other lab tests necessary. 

After leukemia is diagnosed, what other tests are done?

Staging:

Once leukemia is diagnosed, the doctor will determine what stage the leukemia is at. This helps the doctor in making his or her prognosis. Staging for AML and ALL is based on the type of cell involved and how the cancer cells look. CLL, and ALL as well, is staged based on the WBC count at the time of diagnosis. The presence of immature white blood cells, or myeloblasts, in the blood and bone marrow is also used in staging AML and CML.

Disease Progression Assessment:

If leukemia is found in the bone marrow or lymph node samples, the doctor will order more tests to determine whether the disease has spread to other parts of the body and assess the progression of the disease. 
 
The doctor may order a lumbar puncture or "spinal tap" to obtain some of the fluid around the brain and spinal cord and check it for leukemia cells or other signs of problems. It tells the doctor whether the cancer has spread to the central nervous system. A computed tomography (CT) scan, an ultrasound, or other imaging studies may be used to determine if leukemia has spread from the bone marrow and caused damage to other organs. The doctor looks for abnormalities such as enlarged organs or signs of infection in the images generated by these tests.

Other tests can be run to assess the progression of the disease:

  • Flow cytometry - This is an examination of the DNA of the cancer cells and their growth rate.
  • Liver function tests - These show whether leukemia cells are affecting or getting into the liver.