Hematocrit Levels | HCT Blood Test For Blood Cancer

While certain signs and symptoms may indicate that a person has PV, a series of tests are needed to confirm the diagnosis. It is important to have an accurate diagnosis, as it helps the doctor to: 

• Estimate how the disease will progress
• Determine the appropriate treatment

Medical History and Physical Examination

Evaluation of an individual with suspected PV should start with a detailed medical history and a physical examination.

The medical history should include information about the patient’s:

• Cardiovascular risk factors
• Past illnesses and injuries 
• Current and past medications and treatments
• History of thrombus (blood clot) or a hemorrhagic event (loss of blood from damaged blood vessels) 
• Family medical history 
• Current symptoms

After the medical history, the doctor will conduct a physical examination. During the physical examination, the doctor may:

• Listen to the patient’s heart and lungs
• Examine the patient’s body for signs of disease
• Check different organs of the body

Blood Tests

• Complete Blood Count (CBC) with Differential: This test measures the number of red blood cells, white blood cells and platelets in a sample of blood. It also measures the amount of the iron-rich protein that carries oxygen in red blood cells and the percent of whole blood made up of red blood cells (the hematocrit). People with PV have high red blood cell counts. They also often have:
  • Increased hemoglobin levels
  • Increased hematocrit levels
  • Increased white blood cells and platelets
• Red Cell Mast Test: This procedure is used to measure the volume (amount) of red blood cells in relation to the volume of plasma (fluid) in whole blood. In patients with PV, there may be an absolute increase in red blood cell mass. This test is infrequently performed in the United States due to high cost, difficulty obtaining the appropriate test materials, and the advent of new blood tests such as molecular testing.
• Blood Chemistry Profile: This blood test measures the levels of certain substances released into the blood by organs and tissues in the body. These substances include electrolytes (such as sodium, potassium and chloride), fats, proteins, glucose (blood sugar), uric acid and enzymes. The test findings indicate how well a person’s kidneys, liver and other organs are working. Although this test is not used to diagnose PV, if the results show that there is an abnormal amount of a particular substance in the blood, it may be a sign of disease or some other health problem.
• Erythropoietin (EPO) Level. This test measures the level of erythropoietin (EPO) in the blood. EPO is a hormone primarily made in the kidneys to stimulate the production of new red blood cells. In people with PV, high red blood cell counts can suppress EPO levels. Results of EPO tests can be used to help diagnose PV.

Bone Marrow Tests

Your doctor may examine your bone marrow even though the test isn’t needed to diagnose PV.

Bone marrow testing involves two steps usually performed at the same time in a doctor’s office or a hospital:

• A bone marrow aspiration to remove a liquid marrow sample
• A bone marrow biopsy to remove a small amount of bone filled with marrow

In PV, the bone marrow shows above-normal numbers of blood cells and an abnormal number of the platelet-forming cells called “megakaryocytes” in the bone marrow. The pathologist also examines the chromosomes of the bone marrow cells to rule out other blood diseases. 

Molecular Tests

These tests look for abnormal changes in the genes, chromosomes, proteins or other molecules within the patient’s cancer cells. They are used for diagnosis and treatment planning.

Polymerase chain reaction (PCR): This is a very sensitive test used to detect and measure specific genetic mutations that are too small to be seen with a microscope. PCR testing basically amplifies (increases) small amounts of specific pieces of DNA so that they are easier to detect and measure in a cell sample. It looks for the presence or absence of specific gene mutations. PCR testing can be done with blood or bone marrow samples.

DNA sequencing: DNA sequencing refers to a number of different laboratory tests that examine the exact sequence (order) of DNA. By comparing the sequence of DNA in cancer cells with the DNA in normal cells, doctors can find genetic changes that are unique to the cancer cells and may be driving the growth of the patient’s cancer. DNA sequencing can be done with blood or bone marrow samples.

If PV is suspected, testing for the JAK2 gene mutation should be performed. The JAK2 V617F mutation is found in more than 95 percent of PV patients. If a patient does not have a JAK2 V617F mutation, then testing should be done for other mutations. About 2-3 percent of PV patients have the JAK2 exon 12 mutation.

For more information about bone marrow tests and other lab tests, please see the free LLS publication Understanding Lab and Imaging Tests.
 

Criteria for Diagnosing Polycythemia Vera

In 2016, the World Health Organization published new criteria for diagnosing PV.

Diagnosis requires 3 major criteria OR 2 major criteria + 1 minor criterion.

Major Criteria 1.  Very high red blood cell count, usually identified by either A, B, or C below:

• A. Elevated hemoglobin level
  • Hemoglobin levels greater than 16.5 g/dL in men
  • Hemoglobin levels greater than 16.0 g/dL in women
• B. Elevated hematocrit level
  • Hematocrit greater than 49 percent in men
  • Hematocrit greater than 48 percent in women
• C. Increased red cell mass

Major Criteria 2. Bone marrow biopsy showing abnormally high numbers of blood cells in the bone marrow (called “hypercellularity”) based on the person’s age. This includes elevated red blood cell, white blood cell and platelet counts (a condition called “panmyelosis”) and proliferation of mature megakaryocytes (platelet-forming cells) that vary in size and shape

Major Criteria 3. Presence of the JAK2V617F or JAK2 exon 12 gene mutation

Minor Criterion: Very low erythropoietin level

Related Links

• Download or order The Leukemia & Lymphoma Society’s free booklet, Myeloproliferative Neoplasms.
• Understanding Blood Counts
• Bone Marrow Tests
• Lab and Imaging Tests

Understanding the Complete Blood Count (CBC)

The CBC – providing information about your health

The human body is primarily made up of water and cells. Many of the cells group together to form the skin, muscles, bones and organs, such as the heart, lungs, kidneys, etc. Such cells are stationary, staying in one place within the body. Some very special and important cells, however, move throughout the body by traveling (circulating) in the blood. These circulating cells provide oxygen to all of the stationary cells in the body, help fight infection throughout the body, and help stop bleeding after an injury. Information about these cells can provide important clues about the overall health of the body.

The complete blood count, or CBC, is a lab test that provides information about these circulating cells. First, a sample of your blood is collected and sent to the lab. A lab instrument then automatically counts the number of each type of circulating cell. If results from the automated instrument are outside specified limits, a medical technologist will examine the cells closely so complete information about the cells can be provided.

Results from the CBC test can help:

• Provide basic information about your health
• Detect a health condition before you have any symptoms
• Confirm that a health condition exists
• Identify the causes of your symptoms
• Find out if your medicine is working
• Rule out a disease
• Establish a baseline that can be used for comparison with future test results

Reporting and interpreting the results

Your CBC test results are usually reported along with a reference range of expected or desired values to help guide your doctor in interpreting them. Reference ranges reflect the numeric values found in healthy people; however, a small number of healthy people (5%) have values that are higher or lower than the ones shown in the reference range. Thus, values higher or lower than those in the reference range might or might not indicate a medical condition.

In addition to the reference range, your doctor will consider other factors when interpreting your CBC test results. These factors include your personal and family medical history, results from a physical exam, and other test results. Your doctor will also consider factors that might cause an incorrect test result such as improper sample collection or handling. Therefore, it’s important that you talk with your doctor about the meaning of your test results.

This brochure includes a brief description of the items included in the CBC test report. The descriptions can help you understand your results so you can have a more meaningful discussion with your doctor. Additionally, items in the CBC are summarized in the table at the end of this brochure for quick reference.

Red Blood Cells (RBCs) – transporting oxygen throughout the body

RBCs play a vital role in transporting oxygen from the lungs to the rest of the body. These oval-shaped cells contain hemoglobin, the protein that binds oxygen while it is being carried to all the stationary cells in the body (cells in the skin, muscle, bone and organs). The chemical process that converts the nutrients found in food into energy requires oxygen. All the stationary cells require energy to function; thus, they need oxygen and are dependent on the RBCs to transport it.

More about hemoglobin

Hemoglobin (Hb or Hgb) is an iron-rich protein that carries oxygen and makes the blood red. Since hemoglobin is contained only in the RBCs, a low number of RBCs leads to low levels of hemoglobin. However, if there is something wrong with the RBCs, hemoglobin levels can be low even when the RBC count (i.e. number of RBCs) is within the reference range. So a CBC test report includes the number of RBCs, the amount of hemoglobin, and other measurements related to the RBCs.

Other RBC measurements

The hematocrit reflects the amount of space in the blood that is occupied by RBCs. Hematocrit measurements are affected by the number of RBCs and by the size of the RBCs.

The mean corpuscle (cell) volume (MCV) is a measurement of the average size of the RBCs. Small-sized RBCs result in a lower MCV, while larger RBCs result in a higher MCV.

The mean corpuscular hemoglobin (MCH) reflects the average amount of hemoglobin in a person’s RBCs. RBCs with more hemoglobin result in a higher MCH and vice versa.

The mean corpuscular hemoglobin concentration (MCHC) is a measurement of the average amount of hemoglobin in the RBCs compared to the average size of the RBCs. Put another way, the MCHC is the ratio of the MCH to the MCV.

The red cell distribution width (RDW) reflects the degree of variation in size of the RBCs. Not all the RBCs are the same size; some are larger and some are smaller. The RDW measurement is affected by the size of the smallest RBC and the size of the largest RBC.

What this means to me and my doctor

In patients with anemia, hemoglobin levels are low and the patient may be frequently tired and have little energy. This is because there is not enough hemoglobin to carry oxygen to the stationary tissues; thus, there is not enough oxygen available to convert nutrients into energy. The RBC count, hematocrit level, MCV, MCH and MCHC might also be low in patients with anemia.

Low RBC counts, hemoglobin and hematocrit levels can be caused by other things too, such as a lot of bleeding or malnutrition (not enough nutrients in the food eaten). Kidney disease, liver disease (cirrhosis), cancer, and medications used to treat cancer can also cause low levels.

An increased RBC count and increased levels of hemoglobin and hematocrit may be caused by dehydration (not enough water in the body) or by some diseases (see table).

White Blood Cells (WBCs) – defending your body

WBCs help the body fight illness or infection. As part of the immune system, they recognize and fight things that are foreign to (not part of) the body. The number of WBCs (WBC count) is lower than the number of RBCs; however, the WBCs are larger in size RBCs. There are 5 types of WBCs; each type plays a different role in protecting the body from invaders.

What this means to me and my doctor

The WBC count may increase when you have an infection caused by bacteria, viruses, fungi, or parasites. The WBC count can also increase in patients with leukemia, a cancer of the blood. Thus, doctors use the WBC count to help determine if a patient has an infection or leukemia. When the WBC count is increased, the type of WBC can help differentiate between a bacterial infection, viral infection or leukemia. Doctors also use the WBC count to monitor various types of illness, since it may decrease in response to therapy during recovery from an illness. A low WBC count can mean you are at risk of getting an infection since you have fewer WBCs to fight infection.

Types of WBCs

• Neutrophils are cells that protect the body from bacterial infections. They move toward bacteria and then swallow them up so the bacteria cannot harm the body.
• Lymphocytes are cells that protect the body against viruses, bacteria, and fungi. One type of lymphocyte (B-cell) produces antibodies that attack and destroy the bacteria and viruses. Another type of lymphocyte (T-cell) can directly attack viruses and bacteria and can stimulate the B-cells to produce antibodies.
• Monocytes are cells that consume dead or damaged cells. They are the “clean-up crew”.
• Eosinophils are cells that kill parasites and contribute to allergic reactions.
• Basophils are cells that release histamines during allergic reactions.

The differential – visualizing the cells

When performing a differential, a medical technologist looks at the various cells under a microscope. A differential provides information about the relative numbers (that is, the percentage) of each type of WBC. Such information helps the doctor determine whether an illness is caused by a bacteria, a virus, or leukemia. A differential can be used to monitor patients with allergies and to determine how a patient is recovering from an illness or responding to therapy.

In addition to the cell types listed previously, certain cell types that don’t normally appear in the blood can be reported in the differential. These cells include promyelocytes, metamyelocytes, blasts, etc. Presence of any of these cells indicates a need for follow-up with your doctor.

Finally, the differential can provide information about the appearance of RBCs, since the cells are visualized under a microscope. The appearance of RBCs helps differentiate the various types of anemia.

Platelets – helping to clot blood

Platelets are the smallest blood cells. They are an important part of blood clotting. These small cells clump together and form a sticky mass that helps the blood to clot. Blood clots help your body handle injury by stopping or preventing bleeding. Blood clots can also cause problems, however, when they occur within the blood vessels or the heart; such clots cause a blockage known as thrombosis.

Platelet Counts – assessing your body’s ability to clot blood

A CBC includes the number of platelets and the mean platelet volume (MPV). MPV is a measurement of the average size of the platelets. A higher MPV roughly indicates better platelet function. Some medical conditions are associated with a high MPV and some are associated with a low MPV. Thus, the MPV can sometimes be helpful in telling apart different disorders.

A decreased number of platelets (thrombocytopenia) is associated with bleeding. Some causes include certain rare inherited disorders, leukemia, autoimmune disorders (e.g., rheumatoid arthritis or lupus) and medications. A falsely low platelet count, which is not associated with bleeding, can be caused by a rare error in blood sample collection: instead of staying in a liquid form, the sample clots (becomes solid), thus using up the platelets.

An increased platelet count is less common and is associated with clotting disorders such as thrombocythemia. Platelet counts can also be increased in some cancers and following infections or other medical conditions.

Aspirin can decrease the platelet function, so it’s important to consult with your doctor when taking large amounts of aspirin or when taking aspirin for an extended period of time. Many over-the-counter medications contain aspirin, which may be listed as acetylsalicylic acid, salicylate, or 2-(acetyloxy) benzoic acid.

Table: Items included in a CBC Test Report

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What do the results of a clinical blood test say? (continued3)

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WE continue to acquaint our readers with the diagnostic value of clinical blood tests – and in the previous article we have already discussed such indicators as erythrocytes and hemoglobin.

What other indicators are used along with those indicated to monitor the state of both the blood itself and the body as a whole? Traditionally, we address our question to the head of the clinical diagnostic laboratory of the Floris Medical Center LARISA ROGULSKAYA.

– One of these indicators is hematocrit. This indicator reflects the volume fraction (%), which is erythrocytes from the total blood volume. Like any other laboratory value, hematocrit must be evaluated in conjunction with other indicators. An incorrect assessment threatens with an erroneous opinion about the patient’s state of health. For example, in a patient in shock, the hematocrit may be normal due to blood clots, but the red blood cell count may be reduced due to blood loss. Therefore, immediately after bleeding or blood transfusion, the hematocrit value is not indicative of the degree of anemia. But such difficulties with interpretation do not at all detract from the value of the hematocrit value in the clinic. Normally, this figure in adult women is 35-47%, in adult men – 39-50%. An increase in the hematocrit value is noted in some malignant blood diseases, it can be observed in congenital heart defects, respiratory failure, some tumors and polycystic kidney disease. Abnormally elevated hematocrit often occurs with burn disease, peritonitis, dehydration of the body as a result of severe diarrhea or vomiting, sometimes with diabetes.

Decreased hematocrit is a common sign of anemia and may occur with uncontrolled intravenous drips.

One of the most important indicators of a clinical blood test related to erythrocytes is ESR (erythrocyte sedimentation rate). This is an indicator of the rate of separation of blood mixed with a reagent that prevents its coagulation in a thin glass capillary into two layers: a transparent top (blood plasma) and a red-colored bottom (erythrocytes and other blood cells). In fact, how many millimeters the erythrocytes settle within an hour, this will be the ESR indicator.

Healthy adult males have an ESR of 1-10 mm/hour, some up to 15, and men over 50 may have up to 20 mm/hour. Healthy adult women have 215 mm/hour, some have up to 20, and women over 50 may have up to 30 mm/hour. Determination of ESR is a mandatory component of a clinical blood test, performed to detect inflammation of a different nature, and also makes it possible to suspect a tumor process with a high degree of probability, in which the indicator is characterized by consistently high numbers. ESR values ​​also increase in case of poisoning, acute and chronic infections, including pneumonia, osteomyelitis, tuberculosis, myocardial infarction, joint diseases of various origins, injuries and fractures, conditions after surgery, anemia, kidney diseases, as well as when taking certain drugs. A decrease in ESR values ​​(approaching zero) may indicate a dangerous malignant blood disease.

If the determination of the hematocrit value described above is today included in the analytical panel of a modern hematological analyzer, then the measurement of ESR requires the possession of certain practical laboratory skills. In our laboratory, we use world experience, which consists in the use of special disposable blood sampling systems (such as Vacutainer), which already contain the required amount of reagent and vacuum, which allows taking exactly as much venous blood as required for analysis. Thanks to such systems, our specialists avoid possible errors, and therefore the risk of obtaining an incorrect analysis result.

Laboratory doctor of the Floris Medical Center Sergey Dmitruk

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Complete blood count

RBC	Erythrocytes	Normal erythrocytes: 4.2 to 5.6
HCT	Hematocrit (V erythrocytes/ V blood)	Norm ( HCT ): men 42% -52%, women – from 36% to 48%
PLT	Platelets	Norm ( PLT ): 150,000 – 450,000 (per microliter of blood)
WBC	Leukocytes	Norma ( WBC ): 4. 50 to 11.0
HGB	Hemoglobin	Normal hemoglobin: 11.7 – 17.0 g/dl. (g per 100 ml of blood)
LYM	Lymphocytes	Rate ( LYM \ LYMPH ): 20% to 40%
GRAN	Granulocytes	GRA% 47 – 72%
MID	Monocytes	MID 0.2-0.8 x 10 9 /l

CBC (Complete Blood Count) – general blood count. A complete blood count is an important tool in the diagnosis of diseases of the general functioning of the human body. A complete blood count (CBC) provides quantitative and qualitative information about the conditions for a decrease in red blood cells, which indicates anemia, infection, and various disorders.

Red blood cells (RBC) are red blood cells that carry hemoglobin. The main function of erythrocytes is to transport oxygen from the lungs to all tissues and carbon dioxide from the tissues back to the lungs. Few erythrocytes – little hemoglobin. Too little hemoglobin means too few red blood cells. They are interconnected.

Normal red blood cells: 4.2 to 5.6 (number of cells per microliter of blood)

Lack of red blood cells is one of the signs of anemia (anemia). Anemia can be caused by iron deficiency. An excess of red blood cells is called polycythemia. Polycythemia can be caused by a defect in the production of red blood cells in the bone marrow.

Hemoglobin (HGB) – A protein found in red blood cells that is responsible for transporting oxygen molecules to the cells of the body. Hemoglobin is an iron-containing complex that surrounds protein. The level of hemoglobin is not a constant value and depends on age, gender, ethnicity, disease, smoking, in women – on pregnancy, etc.

Normal hemoglobin: 11.7 – 17.0 g/dl (g per 100 ml of blood). There are options depending on gender and age.

Reduced hemoglobin level – severe anemia. Anemia can be caused by a significant lack of red blood cells, acute or chronic blood loss. This is due to a lack of folic acid B9and vitamin B12. Hemolysis (increased destruction of red blood cell membranes) from autoimmune conditions, infections and hereditary blood formation diseases.

Hematocrit (HCT) – shows as a percentage the index of the volume of erythrocytes to the volume of the whole blood sample.

Norm (HCT): men 42% -52%, women – from 36% to 48%

Exception: A low hematocrit indicates anemia (polycythemia). Elevated hematocrit – erythremia.

Leukocytes (WBC) – white or colorless blood cells of various sizes. The main function of leukocytes is to counteract infections, viruses, bacteria, etc. Leukocytes are divided into 5 types: neutrophils, lymphocytes, monocytes, eosinophils and basophils.

Normal (WBC): 4.50 to 11.0 (from 4,500 to 11,000 cubic cells per mC of blood)

Exception: a significant increase or a significant decrease in leukocytes indicates an inflammatory process. The type of leukocytes indicates the nature of the infection.

Neutrophils (NEUT) – Percentage of neutrophils in the blood. Neutrophils are generated in the bone marrow. Their service life in the blood lasts several hours. Neutrophils destroy microbes (phagocytosis).

Normal (NEUT): 40%-75% (neutrophils per 100 leukocytes). Normal values ​​depend on age.

Exception: Elevated neutrophil count indicates inflammation and infection.

Lymphocytes (LYM) are the main cells of the human immune system. Lymphocytes are a type of white blood cell that is produced in the lymphatic system and bone marrow. According to their functions, lymphocytes are divided into B-lymphocytes, which produce antibodies, T-lymphocytes, which fight infections, and NK lymphocytes, which control the quality of body cells.

Norm (LYM \ LYMPH): from 20% to 40% (number of lymphocytes in 100 leukocytes). The normal value varies with age (especially in children).

Exception: An increased number of lymphocytes can be caused by various diseases, especially viral infections.

Eosinophils (EOS \ EOSIN) – white blood cells, characterized by a specific orange color. They take part in the immune system. Elevated in infections with parasites. There is a tendency to appear in allergies and asthma.

Normal (EOS): 0% to 6% (eosinophils per 100 leukocytes)

Exception: An increase in the percentage of eosinophils is a sign of the presence of allergic factors or helminthic invasions.

Monocytes (MONO ) are one of the types of phagocytes, the largest type of leukocytes. Monocytes are formed in the bone marrow. These cells are involved in the regulation and differentiation of hematopoiesis, then go to the tissues of the body and there they turn into macrophages. Monocytes are of great importance, as they are responsible for the initial activation of the entire human immune system.

Normal (MONO): 3% to 7% (of total white blood cells)

Exception: An increase in the percentage of monocytes is a sign of the development of various viral diseases.

Basophils (BASO) is one of the major forms of white blood cells associated with the immune system. The main function is the expansion of blood vessels during infection.

Normal (BASO): 0% to 2% (of total white blood cells)

Exception: An increase in the percentage of basophil cells is a sign of infection or various viral infections.

Platelets (PLT) – Cells that affect blood coagulation. Platelets are responsible for hemostasis, wound healing and bleeding control. Analysis of platelets is important in diseases of the bone marrow in which they are formed. The largest cells in the bone marrow are called megakaryocytes.

Normal (PLT): 150,000 – 450,000 (per microliter of blood)

Exception: Low values ​​(less than 50,000) may indicate a risk of bleeding or a viral infection.