Diagnosis - What Does it Really Mean?

Typically people do not have an idea that they have leukemia before diagnosis. The disease can progress inside the body for years before diagnosis. Usually the first event in a diagnosis happens when the primary care provider (or possibly other specialist) notices an elevated white blood cell count during routine (or specialized) labs, without an explanatory condition. White blood cells can be elevated during infections, so an elevated white blood cell count is not necessarily indicate leukemia.

If leukemia is suspected, the first test the doctor will ask for is a Complete Blood Count (CBC), with differential. The CBC measures and counts red blood cells, platelets, and white blood cells. The differential asks the laboratory to differentiate the different types of white blood cells. This blood draw is usually taken from a vein in the arm. If CLL is present, the CBC will come back with more than 10,000 lymphocytes per cubic millimeter of blood. This condition is called 'lymphocytosis,' meaning too many lymphocytes. However, this result does not always indicate leukemia, and more tests will need to be run. In leukemia, the lymphocytes will also look different than they should, when they are examined under a microscope. When this happens, they are called 'smudge cells.' If the CBC with diff comes back suggesting that CLL is present, the doctor will order another blood test called Flow Cytometry. This test will look at the lymphocytes specifically, and see if they have a certain marker on them that indicates they are CLL. If the cells with these marker are present, and there is more than 5,000 of them per cubic millimeter of blood, a CLL diagnosis can be made.

The blood test is usually enough to diagnose CLL. Most of the time a doctor will order a bone marrow aspiration and biopsy as well at the time of diagnosis. The bone marrow aspiration is a short procedure, where the patient is given a local and/or systemic anesthetic. The doctor inserts a thin, hollow needle into the pelvic bone, and is able to pull about a teaspoon worth of bone marrow out. This bone marrow is then examined, so that the doctors can see if the leukemia cells are mature or immature in their growth, and whether they all cluster together, or spread themselves around in the bone marrow. Both of these pieces of information will help the doctor understand how your disease will progress and what type of treatment will be best for you. If you have CLL, your doctor will likely have you do a bone marrow aspiration and biopsy several times, usually before and after rounds of treatment.

Treatment of CLL will involve other tests as well, possibly including CT and PET scans, so this is not an inclusive list. However, CBC with diff blood draws and bone marrow biopsies are the hallmark tests of leukemia.

References:
How is chronic lymphocytic leukemia diagnosed? 2015. Retrieved April 4, 2015 from http://www.cancer.org/cancer/leukemia-chroniclymphocyticcll/detailedguide/leukemia-chronic-lymphocytic-diagnosis