Chronic lymphocytic leukemia (CLL)

What is chronic lymphocytic leukemia (CLL)?

Chronic lymphocytic leukemia is a blood and bone marrow disease in which the bone marrow makes too many abnormal lymphocytes—a type of white blood cell. CLL is one of the most common types of cancer in adults, and is typically a slow-progressing disease. It is usually diagnosed during a person’s middle age years or after, and is rarely diagnosed in children.

What are the symptoms of CLL?

As with other types of leukemia, there are several symptoms that can lead to a diagnosis of CLL, but many of these signs and symptoms are also indicative of many other illnesses. Most often, CLL is detected when your doctor is testing your blood for another reason and sees the shortage of normal blood cells. This shortage can cause the following symptoms:

  • Fatigue
  • Feeling week, or low energy
  • Dizziness or lightheadedness
  • Fever
  • Enlarged lymph nodes
  • Enlarged spleen, often feeling like pain or “fullness” in the belly
  • Weight loss
  • Night sweats

Many signs of CLL become apparent because the leukemia cells replace the normal blood-making cells in the bone marrow, causing people to have a deficiency in red blood cells, normal white blood cells, and platelets. These changes can cause other issues:

A shortage of red blood cells. It can cause tiredness, weakness, and shortness of breath.
A shortage of normal white blood cells, which can lead to an increased risk of infections.
A shortage of platelets, which can cause excess bruising and bleeding, such as frequent or severe nosebleeds or bleeding gums.

Because of the shortage of normal white blood cells, people with CLL have a higher risk of infection—the immune system is not working as well as it should. CLL is cancer of the lymphocytes that make the antibodies to fight infection. Because these cells aren’t being made like normal, they can’t fight infections.

How is CLL diagnosed?

Many people with CLL don’t have any symptoms when it’s diagnosed—it’s typically found when a doctor orders blood tests for something completely unrelated or during a routine checkup.

Some people may be at higher risk of CLL because they have certain blood disorders, such as myelodysplastic syndrome, or inherited disorders, such as Down syndrome, or because they were treated with certain chemotherapy drugs or radiation. Doctors typically recommend these people have regular checkups.

If you have signs or symptoms of CLL, or if a physical examination indicated you may have leukemia, the doctor will need to take samples of your blood and bone marrow to have it tested to be sure. The blood will be drawn from a vein in the arm, in most cases, but the bone marrow will be extracted in two ways: through an aspiration and a biopsy.

Bone aspiration and biopsy

The bone marrow aspiration and biopsy are done at the same time. Samples are generally taken from the back of the pelvic bone (hip), or sometimes from the sternum (breastbone).

For the aspiration, the patient would lie on a table, either on your side or stomach, and the aspiration site is cleaned. The area is then numbed with a local anesthetic. A thin, hollow needle is then inserted into the bone and a syringe is used to extract a small amount of bone marrow. Even with the anesthetic, some people feel some brief pain when the bone marrow is removed.

The bone marrow biopsy is done right after the aspiration. A small piece of bone and marrow (about 1/16 in diameter and about 1/2 inch long) is removed with a slightly larger needle that is twisted and pushed down into the bone. The biopsy may also cause some brief pain. One the biopsy is done, pressure is applied to the site to prevent bleeding.

These samples are sent to a lab where they are examined for leukemia cells.

Lumbar puncture

CLL can sometimes spread to the brain and spinal cord, and for this reason your doctor may need to take a sample of spinal fluid for testing. The fluid will be extracted using a lumbar puncture—also known as a spinal tap. This test is used only for patients whose symptoms may be caused by the leukemia spreading to the brain and spinal cord.

Blood tests

There are several lab tests that may be used to determine whether you have CLL or how advanced the disease may be.

Complete blood count and peripheral blood smear
A complete blood count (CBC) measures the levels of the different cells in the blood: red blood cells, white blood cells, and platelets. Some of the blood is placed on a slide and examined under a microscope. Most patients with CLL have too many immature white blood cells and not enough red blood cells or platelets.
Blood chemistry and coagulation tests
These tests measure the amount of certain chemicals in the blood, as well as the blood’s ability to clot. These tests aren’t used to diagnose leukemia, but can detect other problems.

Chromosome testing

Normally, human cells contain 23 pairs of chromosomes, or DNA bundles. For people with leukemia, however, the cells may have some chromosome changes—sometimes there is a deletion, or a piece of the chromosome is missing.

What happens more often in CLL is that two chromosomes “share” some of their DNA—one chromosome becomes attached to part of another chromosome. This is called translocation.

Information about these and other changes can help your doctor determine your outlook and response to treatment.

Imaging tests

Imaging tests, like X-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI) scans, and ultrasounds may be used to help doctors see detailed images inside your body.

Should I get screened for CLL?

Unfortunately, there are no screening tests routinely available to detect CLL in the early stages. However, CLL is sometimes detected when certain symptoms show up in routine blood tests done for other reasons. For example, a person’s normal blood cell count may be very low, even if there are no other symptoms. That may lead to other tests in which CLL may be found.

Last reviewed: 
August 2021

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