What are the main tests used to diagnose Chronic Lymphocytic Leukemia (CLL)?

To diagnose Chronic Lymphocytic Leukemia (CLL), physicians rely on a combination of clinical and laboratory tests. These include a complete blood count (CBC) with differential, blood chemistry tests, and flow cytometry, in addition to a physical examination and the patient's medical history. These tests aim to identify the presence of abnormal lymphocytes and assess their impact on the body.

These tests are essential for confirming the diagnosis, determining the type of leukemia, and staging the disease, which helps in developing an appropriate treatment plan. CLL may not present any symptoms in the early stages and is sometimes discovered during a routine blood test [2].

Complete Blood Count (CBC) with Differential

A complete blood count (CBC) is one of the primary and most important tests for diagnosing chronic lymphocytic leukemia. This test involves taking a blood sample and examining it to estimate the number of red blood cells, white blood cells, and platelets [2]. In the case of CLL, a CBC often shows a significant increase in the number of lymphocytes, which are a type of white blood cell [1].

This test also measures the level of hemoglobin (the protein that carries oxygen) in red blood cells and the percentage of red blood cells in the blood sample. Abnormal levels of these components can indicate the presence of the disease and its impact on the production of healthy blood cells in the bone marrow [2].

Blood Chemistry Tests

Blood chemistry tests are used to measure the levels of specific substances released by organs and tissues into the blood. Unusual levels (higher or lower than normal) of these substances can indicate the presence of disease [2]. These tests include measuring levels of lactate dehydrogenase (LDH) and beta-2 microglobulin, which can be elevated in certain cancers, including CLL, and assist in assessing the extent and impact of the disease [2].

Additionally, blood chemistry tests may include assessments of kidney and liver function, electrolyte levels, glucose, proteins, and lipids. These tests provide information on the patient's general health and help in detecting any potential complications of the disease or its treatment [1].

Flow Cytometry

Flow cytometry is considered a critical test for confirming a CLL diagnosis and determining the specific type of leukemia. This test analyzes cells in a sample of blood, bone marrow, or other tissues to determine cell count and percentage, as well as characteristics such as size, shape, and the presence of specific markers on the cell surface [1].

In the case of CLL, flow cytometry helps identify and classify abnormal lymphocytes (leukemic cells), distinguishing CLL from other types of leukemia or other lymphoproliferative disorders. Cells are stained with a fluorescent dye and passed through a light beam, with results analyzed based on how the stained cells react with the light [2].

Genetic and Imaging Tests

After a CLL diagnosis, additional tests may be performed to assess the extent of the cancer and identify factors that may influence the disease course and treatment options. These include genetic tests, such as checking for changes in the TP53 or IGH genes, which can provide important information about the prognosis [2].

Imaging tests, such as chest X-rays, computed tomography (CT) scans, and positron emission tomography (PET-CT) scans, may also be used to evaluate enlarged lymph nodes, liver, or spleen, and to determine if the cancer has spread to other parts of the body [2]. These tests help in determining the stage of the disease and guiding treatment decisions. For more information about this disease, you can visit the page Chronic Lymphocytic Leukemia (CLL): A Comprehensive Guide to Diagnosis, Treatment, and Living with the Disease (Arabic).

Medical references

• Chronic Lymphocytic Leukemia
• Chronic Lymphocytic Leukemia Treatment (PDQ®)–Patient Version