The hematology department is where the cellular components of blood are tested. This includes red blood cells (RBC), white blood cells (WBC), and platelets, which are counted and assessed for abnormalities.
The hematology department receives blood specimens in lavender top tubes.
The most common tests performed in the hematology department include the complete blood count (CBC) and the white blood cell (WBC) differential. A WBC differential is often performed in conjunction with a CBC.
The complete blood count (CBC) is a series of blood tests that include:
- Red Blood Cell (RBC) Count: counts the total number of red blood cells per microliter of blood
- White Blood Cell (WBC) Count: counts the total number of white blood cells per microliter of blood
- Platelet Count: counts the number of platelets per microliter of blood
- Hemoglobin (Hb): measures the amount of hemoglobin in grams per deciliter of blood
- Hematocrit: measures the packed cell volume; the percent of RBCs compared to the total blood volume
The CBC is typically used as a screening test for disorders such as anemia, infection, leukemia, and more.
The WBC differential counts the individual types of white blood cells found in the blood. This is different from the WBC count, which enumerates all white blood cells as one numerical value. The WBC differential quantifies the different types of white blood cells, which could include:
- Neutrophils
- Lymphocytes
- Monocytes
- Eosinophils
- Basophils
If a patient has an infection, a WBC count will show increased total white blood cells. A physician will refer to the WBC differential and absolute values to determine which specific white blood cells are increased. If the WBC differential shows increased neutrophils, the patient may have a bacterial infection. On the other hand, if the WBC differential shows increased lymphocytes, the patient may have a viral infection.
Click "More Info" to see an example of test results for a CBC and WBC Differential (Table 1).
6. Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014." WikiJournal of Medicine 1 (2). DOI:10.15347/wjm/2014.010. ISSN2002-4436. https://commons.wikimedia.org/wiki/File:Blausen_0425_Formed_Elements.png.
