The complete blood count is among the most commonly ordered blood tests by physicians today. This test is the calculation of the different cellular elements that make up blood. These calculations are generally determined with the use of special machines that can analyze all these components in even less than a minute.
There are many indications for the use of this test, as the analysis of blood can cover a vast range of symptoms and aid in disease diagnoses. It may be used as a part of a routine check-up or screening, or also in order to follow-up test to monitor certain treatments. It may also be done as part-in-parcel of an evaluation that is conducted based on a patient’s symptoms. Some other examples of its uses can be to investigate on the cause of symptoms such as fatigue, weakness, fever, bruising, or weight loss. It can be used to locate a hidden anemia. It can be used as an estimate of how much blood has been lost if there is bleeding, whether internally or externally. An overproduction of cellular components such as in polycythemias can be discovered. Similarly, blood diseases like leukemia or blood manifestations such as that of various infections may also be ascertained. It may be used as a tool for assessment as well. Say for example, it can be utilized to check how the body of a cancer patient is dealing with some types of medication or radiation therapy. It can be used to assess a patient’s progression or deterioration in the light of ongoing bleeding. It can be a preoperative assessment tool as well for a patient’s candidacy for surgery. Even allergies and asthma may be investigated based on the amount o presence of certain types of cells within the blood.
Now, the science behind this test depends on the many parameters that are involved. These would be the following:
White blood cell or leukocyte count: The number of white blood cells in the blood. The normal range for the white blood cell count is usually between 4,300 and 10,800 cells per cubic millimeter of blood. A low white blood cell count is called leukopenia. A high white blood cell count is termed leukocytosis. This is essential as the body’s reaction to many conditions can be ascertained through this parameter. Generally, the increase of the count or decrease can symbolize a pathologic condition, such as an infection.
WBC differential count: White blood cell count is comprised of several different types of white blood cells that are differentiated. The cells in a differential count are granulocytes, lymphocytes, monocytes, eosinophils, and basophils. This distinction is particularly important as it makes the study of white blood cell increase or decrease more specific. For example, if one were to note an increase of the count, with a predominance of neutrophils, one would think than the ongoing infection is bacterial in origin. If however, there was a similar increase but it was a predominance of lymphocytes, then one would presume that the origin is viral. Eosinophils similarly are well associated with allergies and parasitic infestations.
Red blood cell count or erythrocyte count: Red blood cells are the ones that carry oxygen. These contain hemoglobin and it is the hemoglobin which allows them to transport oxygen to the body and provides the red color. The RBC count is of value in assessing the presence of the various types of anemias. A decrease in these blood cells would alert the physician to investigate further into a patient as to the possible underlying cause of why the patient is underproducing, or overproducing for that matter, the very important oxygen carrying cells.
Hematocrit: The hematocrit is the proportion, by volume, of the blood that consists of red blood cells. The hematocrit is expressed as a percentage. It gives an estimate of how much sold component is present in blood versus liquid component. For example, a hematocrit of 245% means that there are 45 milliliters of red blood cells per 100 milliliters of blood. A decrease of hematocrit would signify that the amount of blood cells per unit volume is below in ration and again notify for further investigation.
Hemoglobin: As previously mentioned, hemoglobin is the protein molecule in red blood cells that carries oxygen in transport from the lungs all around the body’s tissues. Likewise, it also takes care of the return of carbon dioxide from the tissues to the lungs for release into the environment. As it is this component that makes the red blood cell capable of carrying blood, then monitor of its amount reflects that body’s oxygen carrying capacity. A low amount would be a warning that although the body has enough blood, it does not have adequately functioning blood for oxygen delivery.
Mean corpuscular volume: This is a standard part of the test that gives us the average volume of a red blood cell. This is a calculated value derived from the hematocrit and the red cell count. A normal range for the mean cell volume is 86 – 98 femtoliters. This is important as it helps a physician classify anemias and identify causative factors. For example, a low MCV in anemia would point toward a deficiency in iron in some cases, leading to a lower production of hemoglobin which needs iron for its production.
Mean corpuscular hemoglobin: This is the average amount of hemoglobin in the average red cell. The mean cell hemoglobin (MCH) is a calculated value derived from the measurement of hemoglobin and the red cell count. It is also essential to help in a physician’s determination for the possible etiology of an anemia. For example, a deficiency in iron causing anemia can also cause low MCH values. Hence, if a patient has a low RBC count, with a low MCV and a low MCH, then the physician would lean toward iron-deficiency as a cause for the anemia Mean corpuscular hemoglobin concentration: This is the average concentration of hemoglobin in a given volume of blood. The MCHC is also a calculated value derived from the measurement of hemoglobin and the hematocrit. The normal range for the MCHC is 32 – 36%.
Red cell distribution width: This is a measurement of the variability with respect to the size of the red blood cell. If the levels are high, it indicates greater variation in RBC size. The normal range for the red cell distribution width (RDW) is 11 – 15.
Platelet count: This is the calculated number of platelets in a volume of blood. This is an important component as it measures the smallest cell-like structures in the blood, which are primarily needed for blood clotting and plugging damaged blood vessels. Normal platelet counts are in the range of 150,000 to 400,000 per microliter. This is extremely important for ascertaining the cause of bleeding. Low counts could point a diagnosis toward infections such as dengue hemorrhagic syndrome, or immunologic disorders like immune thrombocytopenic purpura. They would alert the physician of the possible etiologies of a patient’s bleeding.
As this procedure only entails withdrawal of blood from a patient’s vein, there is very little chance of a problem arising. Some minimal risks or potential complications would be a small bruise at the site, which can be prevented or at least have its chance lessened by keeping pressure on the site for several minutes. In rare cases, it is possible that the vein may become swollen after the blood sample is taken in a condition called phlebitis. This is simply treated with a warm compress several times a day. A real problem can arise though for people with bleeding disorders or on blood-thinning medicines, as it can cause ongoing bleeding. Nevertheless, as it is a small puncture wound, the bleeding can well be managed. There is still greater benefit from discovering the blood disorder rather than not having the test.
Monospot test
This test is a blood test that is used to look for antibodies that indicate mononucleosis, which is caused by the Epstein-Barr virus. The antibodies are a reaction of the immune system to fight an infection from the virus, and are proof of exposure. Monospot testing can usually detect antibodies 2 to 9 weeks after a person is infected. This test is used by physicians to diagnosis conditions such as infectious mononucleosis so they may be treated accordingly. Its significance is differentiating diseases that may present similar to mononucleosis, such as cytomegalovirus infections, leukemia, lymphoma, rubella, hepatitis, or lupus.
The ability to get good results from this test may be affected by a few factors. Having a test within the first few weeks of becoming infected may lead to a negative result, primarily because the antibodies may not have been produced yet. If the first test does not indicate the disease, but clinically the patient still has typical symptoms, the test may be repeated.
As the administration of this also involves a needle prick, risks are pretty much the same as that of a complete blood count.
