What is a Hematology Test? - Common Tests & Interpretations

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  • 0:03 What Is Hematology?
  • 1:02 Complete Blood Count Test
  • 4:39 Bleeding and Clotting Tests
  • 6:03 Lesson Summary
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Lesson Transcript
Instructor: Lisa Cauthen

Lisa is a Registered Nurse with a 14 years of experience and a Masters Degree in Nursing Education. She has certifications in CPN, ACLS, PALS, and NRP.

A hematology test is a measurement of blood to help diagnose and monitor many conditions. This lesson explores specific hematology tests along with normal values and their interpretations.

What Is Hematology?

Let's say you had a blood test done. You call the laboratory to see if results are in, but the receiver says, ''This is chemistry; you need micro'' or ''Let me transfer you to hematology.'' Did you know there were labs within the lab? There are. Each department within a laboratory specializes in certain tests. Let's see just what's going on in the hematology department of the lab.

Hematology (hema- is from the Greek word for 'blood') is the study of blood in regards to a person's health or disease. It includes blood, blood-forming organs, and the proteins involved in bleeding and clotting.

Hematological tests can evaluate numerous conditions involving blood and its components. They can also be used to diagnose inflammation, anemia, infection, hemophilia, blood-clotting disorders, leukemia, and response to chemotherapy, among many other things. Let's take a look at some of these tests.

Complete Blood Count Test

A complete blood count (CBC) measures several components and features of your blood. A CBC and its individual components are tested on whole blood. It can include measurements of the following:

1. White Blood Cells

White blood cells (WBC) make up the body's primary defense system, and knowing their number is an important tool in diagnosing and monitoring infection and leukemic disorders. A normal WBC level is 4,500 - 11,000 per mm³ of blood.

Increased WBC levels are most notably found in those with any type of infection, but are also found in anemia, collagen disorders, and those with physiologic stress, such as pregnancy. Low WBC levels are seen in malnutrition, rheumatic disorders (like lupus, arthritis), some viral infections, and those undergoing chemotherapy or other forms of bone marrow suppression.

2. Red Blood Cells

Red blood cells (RBC) are responsible for the transport and exchange of oxygen. Measurement of RBCs is important in monitoring the effects of blood loss and the progression of chronic disease. Normal counts of RBCs are 3,900,000 - 5,800,000 per mm³ of blood.

RBC values are increased in those with anxiety or stress, bone marrow failure, and dehydration. A decreased RBC value will be found in those with chronic inflammatory diseases, chemotherapy patients, anemia, blood loss, and many cancers.

In addition to a count of WBCs and RBCs, a complete blood count can include further tests to evaluate the size, weight, and shape of those cells. These more detailed tests are helpful in diagnosing and monitoring therapy for cancer and anemic patients.

3. Hemoglobin

Hemoglobin (HgB) is the oxygen-carrying protein in red blood cells. Hemoglobin levels are a direct reflection of the amount of oxygen in the blood. A normal hemoglobin concentration is 11-15 grams per deciliter of blood.

Increased HgB is seen in those with dehydration, chronic obstructive pulmonary disease, or COPD, and congestive heart failure, or CHF, and those at high altitude. A decreased HgB value is seen in anemia, blood loss, liver disease, as well as leukemia and lymphomas.

4. Hematocrit and Platelets

Hematocrit (HCT) is the proportion of red blood cells to plasma, the fluid component of your blood. HCT helps to evaluate anemia and hydration. A normal percentage of hematocrit is 33 to 49%. The increase and decrease levels of HCT mirror those of hemoglobin. RBC, HgB, and HCT tests parallel each other and are frequently used together to evaluate anemia.

Platelets (PLT) have an essential function in blood clotting. A normal value is 150,000 - 450,000 platelets per mm³ of blood. An increased platelet value is seen in conditions that involve inflammation, such as acute infection, trauma, and some malignant cancers. A decreased platelet count is found in alcohol toxicity, anemia, blood loss, infection, many congenial conditions, and coagulation disorders.

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