What is a CBC?
Patients have blood work all the time when they are going through treatment and follow up. What are we testing?
A CBC is a Complete Blood Count. It measures :
The number of white blood cells, which fight infection.
The number of red cells, which contain hemoglobin. These carry oxygen from the lungs to the rest of the body. When these numbers go down, less oxygen is delivered to the body, and this causes fatigue, or shortness of breath.
The number of platelet cells, which are essential to stop bleeding. When these are low, people bruise or bleed easily.
A CBC with D (with differential) shows the numbers of the kinds of white cells, which fight viral infections, vs. bacterial infections, vs. allergies, or parasitic infections.
Chemotherapy or Radiation therapy will reduce the numbers of good cells.
Infections will increase the numbers of infections fighting white cells.
The CBCD is routinely checked throughout treatment, to make sure the bone marrow (the factory where the blood cells are produced) has enough reserve to get through the next treatment. After treatment is completed, it is checked to make sure the bone marrow has recovered, and has not suffered any ill effects.
During a cycle of chemotherapy, the counts change in cyclical fashion; they dip a week after chemotherapy, then recover in the next 10 days.
If the white cell count is low, and treatment needs to continue on schedule, there is an injection, which will help a faster recovery. If that is not required, the doses of chemotherapy are adjusted to prevent major drops in counts. If the red cell count is low, any Iron deficiency is replaced, and sometimes blood transfusions or injections are required.
Other blood tests that are monitored during and after treatment are tests that measure liver function (LFTs) and kidney function. Chemotherapy dosage changes may be required if these go down. Drastic changes are trigger points for more investigation.