BETA - What is listed on a CBC report?

There are lots of different things listed in a CBC report. It lists the different types of blood cells, the main groups being white blood cells, red blood cells, and platelets. There are different types of white blood cells, usually the most common being neutrophils, which are the infection-fighting cells, particularly for fighting off bacterial infections. But there are also lymphocytes, monocytes, eosinophils, and basophils. Those are all different types of white blood cells. The platelets are there to help you stop bleeding, and so we measure those. And then we measure the red blood cells, both numerically and then different aspects of them. So there are lots of different measurements of red blood cells. The ones that are most important are the hemoglobin and the hematocrit. But you'll also see things like red blood cell count, the red blood cell diameter width, or the RDW, and the different sizes of those blood cells. And those numbers help us figure out what may be going on. Are you making a lot of them? A few of them? Are you low in vitamins? And a variety of different things that can help us make diagnoses, but also help adjust treatments. Well, there are three different ways we can have lab results. One is in weight, and that's in milligrams per deciliter or grams per deciliter. Others are in counts, like the white cell count, the platelet count, and the red blood cell count. It's in how many there are per microliter. And then there are the units. The units are usually a measure of enzymatic activity. They have nothing to do with the weight of the enzyme or anything. They're just measuring enzymatic activity. For example, if you look at liver functions like an ALT and an AST, that will be typically expressed in units per liter. The CBC reflects the bone marrow function. And the bone marrow makes three different types of cells. It makes the red blood cells, it makes the white blood cells, and it makes the platelets. And the red blood cells are the cells that are carrying around oxygen and make us feel not tired. If we have a low red blood cell count, people will feel tired. The white blood cell count is related to infection. If the white blood cell count is low, there is an increased risk of infection. And the platelets are related to bleeding. If the platelet count is very low, there is an increased risk of bleeding. When we look at the CBC, we're looking at several aspects. With regard to the red blood cells, we're looking for evidence of anemia. And in particular, we're measuring the hemoglobin in the hematocrit. And sometimes, if someone is anemic, we will give a blood transfusion. But sometimes, we can also give blood growth factors, erythropoietin, to help stimulate the bone marrow to make more blood cells. Sometimes it tells us we might need to adjust a treatment, either reducing a dose or extending an interval of time. White blood cells are really important to help fight off infection. And those numbers are probably one of the more critical numbers that we look at when we're monitoring treatment. Because many times, if those numbers drop too low, our patients are at significantly higher risk of getting an infection, particularly a bacterial infection. So that may mean that we need to extend the time until we give the next cycle of treatment or stop it early or reduce our doses of medications if those numbers drop too low. We tend to look at something called the absolute neutrophil count, which can many times be abbreviated ANC on the report. And if that number drops below 500, certainly that's a potentially dangerous level. But if it drops below 1,000, we often will make adjustments in doses. Now, some reports will put that as 1.0, and others will list out a full number as 1,000. Those are both measurements of the same type of assessment. Sometimes we often give antibiotics to help prevent infection if those numbers are too low. And even sometimes, we give growth factors to help stimulate those white blood cells to recover faster. We also look at the platelets. Those help stop bleeding. And if those numbers drop too low, again, certainly less than 30,000, but oftentimes less than 50,000 or even higher numbers, we will often make adjustments in treatment to hopefully not let those counts drop as low. Sometimes though, the disease itself will be filling up the bone marrow and making any or all of those different numbers on the low side. And if that's the case, we have to give treatment regardless of how low those numbers are, because we can't get those numbers up until we clear out the bone marrow of the myeloma or leukemia or other diseases. So the numbers themselves are not absolute. They have to be taken into consideration when one looks at a different patient's particular clinical situation. So the reference ranges on those reports refer to the population as a whole, people who do not have underlying blood disorders. So many times our patients, both at the time of diagnosis on treatment and even after finishing treatment, will have blood values that are outside of those normal ranges. There's not an absolute number other than looking at particularly low neutrophils, hemoglobins, or platelets. And that being a neutrophil count less than 1,000, a hemoglobin less than 8, and platelets less than about 30,000 that we would be particularly concerned. But perhaps more importantly is what's the trend over time? So that if someone's hemoglobin level is living at 8 consistently and doesn't change, that is likely where that patient's baseline is. But if, for example, a patient's hemoglobin has been in the 12 range and suddenly is 9 or 8, that would be much more concerning. So we don't just take absolute values, we look at the trends in those values over time. So we try to make the distinction whether we think blood counts are low because of treatment or the disease in part by looking at the bone marrow or knowledge of the bone marrow and then also looking at the other markers, if we have them, of the disease in the blood. So for example, if a patient's M-spike with regard to myeloma is rising week over week or month over month and the blood counts are low, it may very well be related to disease. But if the disease is responding to treatment and the counts are low, it's much more likely to be related to treatment. But we'll often need to get a bone marrow biopsy to try to help us figure that out. Although the CBC is very important, it is often not the first indicator of relapse for patients. We often will see changes more in the protein and the M-spike level before we see changes in the CBC. That said, there are patients whose predominant disease is non-secretory and they don't have protein and they don't have light chains. And in situations like that, we may see falls in one or more of the lab parameters. Probably the one that is the most sensitive or certainly one in patients who have smoldering myeloma that we're following to try to decide if they need to go on treatment are subtle declines in the hemoglobin level with everything else remaining the same.