How Chronic Lymphocytic Leukemia Is Diagnosed

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Doctors will perform a battery of tests to diagnose chronic lymphocytic leukemia (CLL). This usually slow-growing blood cancer affects specific white blood cells called lymphocytes, which are produced in the bone marrow and are involved in immune functions.

In many people, early-stage CLL doesn’t produce any noticeable symptoms. Healthcare providers may only realize something is wrong after getting back abnormal routine blood test results. Healthcare providers who suspect CLL will perform further testing. 

This article discusses the steps involved in diagnosing CLL.

Phlebotomist drawing blood sample for testing

simon's photo / Getty Images

Self-Checks/At-Home Testing 

There’s no reliable way to test for CLL at home. Many people who have this type of blood cancer may not even know they have it.

You may have no symptoms early on or experience vague, nonspecific symptoms that can be hard to attribute to one cause.

Physical Examination 

Doctors will usually ask you about your medical history, including:

  • What symptoms you’re experiencing
  • How long you’ve had bothersome symptoms
  • Whether you have any risk factors for CLL
  • Whether you have any other health issues

Chronic Lymphocytic Leukemia Symptoms

Symptoms of this type of blood cancer may include:

  • Tiredness or feeling run-down
  • Recurring infections
  • Swollen lymph nodes
  • A feeling of pressure or fullness in the abdomen
  • Easy bleeding or bruising
  • Fever 
  • Chills
  • Weight loss
  • Night sweats

However, many people don’t have symptoms at the time of their initial diagnosis.

During the physical exam, your healthcare provider will also check for swollen lymph nodes.

They may also ask the following questions to determine whether you have any risk factors for CLL:

  • Do you have a family history of CLL or other blood cancers?
  • Have you had prior exposure to herbicides such as Agent Orange, or were you in Vietnam during the Vietnam War? (This chemical was used to kill vegetation at that time.)
  • Have you been exposed to radon? (This is a colorless, odorless gas that may be present in homes and other buildings.)

Labs and Tests 

A healthcare provider who suspects you have chronic lymphocytic leukemia will check your blood by drawing it from a vein in your arm.

Healthcare providers may suspect CLL only after seeing the results of routine blood tests, particularly a complete blood count (CBC). In this case, they may request further testing (such as a blood smear, a sample of blood tested on a specially treated slide) to check for or verify the presence of:

  • A high white blood cell count, specifically lymphocytes
  • A low red blood cell count (cells that carry oxygen to the tissues)
  • A low platelet count (cells involved in clotting)
  • Abnormal appearance of lymphocytes, also known as smudge cells
  • Beta-2-microglobulin, which may mean you have a more advanced case of CLL

Flow cytometry is a test that can help identify cells by their characteristics. In the case of CLL, flow cytometry can identify whether lymphocytes contain cancerous cells. This test can help differentiate CLL from diseases with similar symptoms.

Bone marrow aspiration or biopsy can help healthcare providers determine how far advanced the cancer is and check whether you’re responding to treatment. In this procedure, a needle is inserted into a bone (often the hip) to remove some of the bone marrow to be analyzed in a lab.

Rarely, a spinal tap, in which a needle is used to obtain a sample of cerebrospinal fluid from your spinal canal, or a lymph node biopsy (removing a sample lymph node for testing) are used to determine the spread of CLL.

Additionally, healthcare providers may recommend genetic testing to check for chromosomal abnormalities (changes in the structures in the nuclei of cells that carry genes). This can help them determine which treatment might work best for your condition.


Healthcare providers don’t typically use imaging tests to diagnose CLL. Still, they can use them to check whether the cancer has spread and to find out whether treatment is working:

  • A computed tomography (CT) scan can tell your healthcare provider whether your lymph nodes are enlarged. This type of imaging test can also show whether the cancer has spread to your organs.
  • Magnetic resonance imaging (MRI) can tell your healthcare provider if there is any brain or spinal cord involvement, but it’s rarely used to diagnose CLL. 
  • Ultrasound technology can help your healthcare provider identify enlarged lymph nodes or organs like the liver or spleen, which may be a sign of CLL, as well as a factor in prognosis (outcome).

Differential Diagnosis 

Because many blood cancers present similarly and share symptoms, your healthcare provider may enlist the help of a hematopathologist, a doctor specializing in laboratory medicine, blood disorders, and blood cancer.

Other conditions with similar symptoms include:


To diagnose chronic lymphocytic leukemia, healthcare providers will start by taking a medical history and performing a physical examination. If they suspect CLL, they will order a complete blood count and other blood tests.

They may also use genetic testing to confirm a diagnosis and help guide treatment options. A bone marrow biopsy and imaging can help doctors determine whether the cancer has spread.

A Word From Verywell

Waiting for a diagnosis of chronic lymphocytic leukemia can feel daunting. But keep in mind that CLL is typically a slow-growing cancer and medical professionals have many tools at their disposal to help manage and control the disease. Once you have a confirmed diagnosis, your healthcare provider can help you determine the right treatment plan for your needs. 

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. American Cancer Society. Signs and symptoms of chronic lymphocytic leukemia.

  2. American Cancer Society. How is chronic lymphocytic leukemia diagnosed?

  3. American Cancer Society. What are the risk factors for chronic lymphocytic leukemia.

  4. Leukemia & Lymphoma Society. Related diseases.

  5. National Cancer Institute. Chronic lymphocytic leukemia treatment (PDQ)-Patient version. Updated September 20, 2021.

  6. National Organization for Rare Disorders. Chronic lymphocytic leukemia.

By Steph Coelho
Steph Coelho is a freelance health and wellness writer and editor with nearly a decade of experience working on content related to health, wellness, mental health, chronic illness, fitness, sexual wellness, and health-related tech.She's written extensively about chronic conditions, telehealth, aging, CBD, and mental health. Her work has appeared in Insider, Healthline, WebMD, Greatist, Medical News Today, and more.