The Complete Blood Count (CBC) is one of the first tests run by a doctor when you are feeling unwell. It counts and measures many aspects of both your red and white blood cells.
Your blood is made up of red blood cells (RBC), white blood cells (WBC) and platelets, suspended in a light straw-yellow liquid, called plasma.
If your RBCs are low, you may be anemic.
If your WBC are high, you may be fighting an infection, or have inflammation somewhere.
If WBC are low, you may be fighting a long-term chronic infection that has worn your immune system down over time.
Platelets enable clotting: if high, there is a tendency to form clots; if low, healthy clotting may be impeded.
You can see why this is a good place to start checking what’s up (or down)! So let’s look at red blood cells first.
Red Blood Cell Differential:
RBC is the total number of red blood cells, also known as corpuscles. If the number is low, there may have been blood loss, for example due to an accident, surgery or just heavy menstruation. Sometimes the body isn’t producing RBCs fast enough, which may be due to an illness or some kinds of chemotherapy.
Hgb is total Hemoglobin. This is the protein in your red blood cells that grabs oxygen from your lungs, and transports it around your body. If total hemoglobin is low, we look further, as iron deficiency anemia is likely.
MCHC is Mean Corpuscular Hemoglobin Content. It tells us the average amount of hemoglobin in our red blood cells.
MCV is Mean Corpuscular Volume, the average size of your red blood cells. RBCs live 3-4 months, so we need to keep making new ones. Younger cells are larger, so we will always see some of them. But if we see too many, we think of B 12 or folate deficiency, or recent blood loss requiring more new RBCs to be made. On the other hand, if we see lots of smaller RBCs, we think of iron deficiency anemia.
RDW is Red Cell Distribution Width. This measures how much the sizes of your red blood cells vary, between the largest and smallest ones. If the sizes vary more than normal, more testing is indicated to find out why.
HCT is HematoCriT. It measures the concentration of red blood cells in the blood. If it is low, there may iron deficiency anemia perhaps due to excess bleeding.
Platelets are the small molecules that form clots when activated. It is this process that aspirin and some of the anti-clotting drugs work to prevent.
If your platelet levels are low, your ability to clot is reduced, and you may find you bleed or bruise more easily. If it is high, you have a greater tendency to form clots, which can cause many problems. High or low platelets can be symptoms of many diseases, so it is test that tells us something is going on, but not why that is. It's a red flag, telling us to look further.
It is easy to crack the code of your bloodwork once you know what the letters and numbers represent. Do remember that one number out of balance is not a definitive diagnosis, and may not get you to the full answer about what’s going on. But this test is an important step in understanding your overall health.
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