Tests That Help Evaluate CLL
Your doctor may request tests to learn more about your specific type of leukemia and to see if the leukemia is causing any other problems in your body. This will help your doctor decide on the most effective types of treatment for you. You may need one or more of these tests.
A chest X-ray uses radiation to produce a picture of the organs and glands inside your chest. This test cannot show leukemia cells. But it can show if you have an infection in your lungs resulting from leukemia. It can also help your doctor see if lymph nodes in this area are swollen. The test takes only a few minutes, and it won't cause any pain.
Computed tomography (CT) scan
A CT scan takes X-ray pictures of different parts of your body from many different angles. Although this scan takes longer than an X-ray, it allows your doctor to get a better look at a particular area of your body than an X-ray allows. A CT scan can spot swollen lymph nodes and glands, pockets of infection in your organs, and large clusters of leukemia cells.
To have the test, you lie still on a table as it gradually slides through the center of the CT scanner. Then the scanner directs a continuous beam of painless X-rays at your body. A computer uses the data from the X-rays to create many pictures, which can be used to create a three-dimensional picture. You may be asked to hold your breath one or more times during the scan.
In some cases, you will be asked to drink a contrast medium after an initial set of pictures is taken. This dye outlines your intestines so that they won't be mistaken for a tumor or a pocket of infection. The contrast will later pass through your system and exit through your bowel movements. If you receive it, instead, through an intravenous (IV) injection in your arm, this contrast dye may cause a feeling of warmth. In rare cases, it can also cause hives or other allergic reactions. Let your doctor know about any reactions you have or if you have had any reactions in the past.
Bone marrow aspiration and biopsy
Bone marrow samples are usually taken from the back of the pelvic (hip) bone. Although these tests are not usually needed to diagnose CLL, they may help find out how advanced it is. Bone marrow aspiration and biopsy are commonly done before starting treatment to see how much CLL is in the bone marrow and may be repeated during or after treatment to see if the treatment is effective.
In bone marrow aspiration, the area over the hip is numbed and a thin, hollow needle is inserted into the hip bone. A syringe is used to suck out a small amount of liquid bone marrow. Even with the anesthetic, you may have some brief pain when the marrow is removed. A bone marrow biopsy is usually done just after the aspiration. A small piece of bone and marrow is removed with a slightly larger needle that is pushed down into the bone. The biopsy may also cause some brief pain.
Flow cytometry and immunohistochemistry
These lab tests are used on blood, bone marrow, or other tissue samples for immunophenotyping, which is the determination of specific substances on the surface of the leukemia cells. These tests can be used to make the diagnosis of CLL.
Flow cytometry can also be used to test blood for substances called ZAP-70 and CD38. These substances seem to be linked to what type of B lymphocyte is involved in the leukemia. Research suggests that CLL with fewer cells that express these substances may have a better outlook. Tests for these substances are still new and may not be available in all labs.
The lab looks for changes in the chromosomes of cells from samples of peripheral blood, bone marrow, or lymph nodes. For example, in some cases of CLL, part of a chromosome may be missing. This test usually takes a few weeks because the cells need time to be grown in the lab. Because of this, it is not used as often as in the past.
Newer tests for CLL
Fluorescent in situ hybridization (FISH) is a type of cytogenetic test that uses special fluorescent dyes that only attach to certain parts of certain chromosomes. It can be used to look for specific changes in chromosomes found in regular blood or bone marrow samples and does not require that the cells grow in the lab first. The FISH test is very accurate and provides results more quickly than standard cytogenetic tests, which is why it is now used in many medical centers.