What is hematocrit in blood work. How is the hematocrit test performed. What are the normal hematocrit ranges for adults and infants. Why might a doctor order a hematocrit test. What do abnormal hematocrit results indicate.

What is Hematocrit and Why is it Important?

Hematocrit (HCT) is a crucial blood test that measures the percentage of red blood cells in a person’s total blood volume. This measurement provides valuable insights into an individual’s overall health and can help diagnose various medical conditions.

The importance of hematocrit lies in its ability to indicate:

• Oxygen-carrying capacity of the blood
• Potential presence of anemia or polycythemia
• Hydration status
• Effectiveness of certain treatments

Understanding hematocrit levels can help healthcare providers make informed decisions about patient care and treatment strategies.

The Role of Blood in the Human Body

Blood plays a vital role in maintaining overall health and well-being. Its functions include:

1. Transporting oxygen and nutrients to body tissues
2. Removing waste products and carbon dioxide
3. Distributing hormones from endocrine organs to target tissues
4. Regulating body temperature
5. Maintaining normal pH levels in body tissues
6. Forming clots to prevent excessive bleeding
7. Defending the body against infections

Given these critical functions, monitoring blood components, including hematocrit levels, is essential for assessing overall health and detecting potential issues.

The Hematocrit Test Procedure: What to Expect

The hematocrit test is a simple and relatively painless procedure. Here’s what you can expect:

• A healthcare professional will draw a small blood sample from a vein in your arm
• The sample is then analyzed in a laboratory
• Results are typically available within a few hours to a day

Is special preparation required for a hematocrit test? No special preparation is necessary. You can eat and drink normally before the test unless your healthcare provider advises otherwise.

During the blood draw, you may experience:

• A brief sting or prick when the needle is inserted
• Slight discomfort or throbbing at the injection site
• Potential bruising, which usually resolves quickly

Normal Hematocrit Ranges: Understanding Your Results

Hematocrit levels can vary based on age, sex, and other factors. Here are the generally accepted normal ranges:

For Adults:

• Males: 40.7% to 50.3%
• Females: 36.1% to 44.3%

For Infants:

• Newborns: 45% to 61%
• Infants: 32% to 42%

Do these ranges apply to all laboratories? It’s important to note that normal value ranges may vary slightly among different laboratories. Some labs might use different measurements or test different samples. Always consult with your healthcare provider to interpret your specific test results accurately.

Reasons for Ordering a Hematocrit Test

Healthcare providers may recommend a hematocrit test for various reasons, including:

• Suspicion of anemia or other blood disorders
• Monitoring chronic medical conditions like kidney disease
• Assessing overall health during pregnancy
• Evaluating unexplained fatigue or weight loss
• Investigating persistent headaches
• Checking for blood loss due to heavy menstrual periods or gastrointestinal bleeding
• Monitoring treatment for cancer or leukemia
• Evaluating the effects of certain medications on blood counts
• Assessing nutritional status
• Investigating concentration problems

Is the hematocrit test always performed alone? The hematocrit test is typically part of a complete blood count (CBC), which provides a comprehensive overview of blood cell components.

Interpreting Low Hematocrit Results: Causes and Implications

Low hematocrit levels can indicate various health issues. Some potential causes include:

• Anemia
• Acute or chronic bleeding
• Bone marrow disorders affecting red blood cell production
• Chronic illnesses
• Kidney disease
• Hemolysis (destruction of red blood cells)
• Leukemia
• Malnutrition
• Deficiencies in iron, folate, vitamin B12, or vitamin B6
• Overhydration

What are the potential consequences of low hematocrit? Low hematocrit can lead to reduced oxygen delivery to tissues, resulting in fatigue, weakness, shortness of breath, and other symptoms associated with anemia.

High Hematocrit: Causes and Health Implications

Elevated hematocrit levels can also indicate underlying health issues. Potential causes of high hematocrit include:

• Polycythemia vera (a bone marrow disorder causing overproduction of red blood cells)
• Dehydration
• Chronic lung diseases
• Congenital heart defects
• Living at high altitudes
• Smoking
• Use of performance-enhancing drugs (e.g., erythropoietin)

What are the risks associated with high hematocrit? Elevated hematocrit levels can increase blood viscosity, potentially leading to blood clots, stroke, or heart attacks. It’s crucial to identify and address the underlying cause of high hematocrit to prevent these complications.

Hematocrit and Other Blood Tests: A Comprehensive Approach

While hematocrit is a valuable indicator of health, it’s often interpreted alongside other blood tests for a more comprehensive assessment. These may include:

• Hemoglobin concentration
• Red blood cell count
• White blood cell count
• Platelet count
• Mean corpuscular volume (MCV)
• Mean corpuscular hemoglobin (MCH)
• Mean corpuscular hemoglobin concentration (MCHC)

How do these tests complement hematocrit results? By analyzing these parameters together, healthcare providers can gain a more complete picture of blood cell production, size, and function, allowing for more accurate diagnoses and treatment plans.

Factors Affecting Hematocrit Levels

Several factors can influence hematocrit levels, including:

• Age and sex
• Pregnancy
• Altitude
• Hydration status
• Recent blood loss or transfusions
• Certain medications
• Exercise habits
• Smoking

Understanding these factors is crucial for accurately interpreting hematocrit results and developing appropriate treatment strategies.

Monitoring Hematocrit Levels Over Time

Regular monitoring of hematocrit levels can be beneficial for:

• Tracking the progression of chronic conditions
• Assessing the effectiveness of treatments
• Detecting early signs of blood disorders
• Monitoring overall health and wellness

How often should hematocrit levels be checked? The frequency of hematocrit testing depends on individual health status, existing medical conditions, and healthcare provider recommendations.

Lifestyle Factors Affecting Hematocrit

Certain lifestyle choices can impact hematocrit levels:

• Diet: Adequate intake of iron, folate, and vitamin B12 is essential for healthy red blood cell production
• Hydration: Proper hydration helps maintain appropriate hematocrit levels
• Exercise: Regular physical activity can influence hematocrit levels, potentially increasing them slightly
• Smoking: Tobacco use can artificially elevate hematocrit levels

Making positive lifestyle changes can help maintain healthy hematocrit levels and overall well-being.

Hematocrit in Special Populations

Certain groups may require special consideration when interpreting hematocrit results:

• Pregnant women: Hematocrit levels naturally decrease during pregnancy due to increased plasma volume
• Athletes: Endurance athletes may have slightly elevated hematocrit levels due to plasma volume changes
• Older adults: Hematocrit levels may naturally decrease with age
• People with chronic diseases: Certain conditions can affect hematocrit levels and require ongoing monitoring

Healthcare providers consider these factors when interpreting hematocrit results and developing treatment plans.

Advances in Hematocrit Testing

Recent technological advancements have improved hematocrit testing:

• Point-of-care testing devices allow for rapid results in various healthcare settings
• Automated hematology analyzers provide more accurate and precise measurements
• Non-invasive hematocrit measurement techniques are being developed, potentially reducing the need for blood draws

These innovations contribute to more efficient and patient-friendly hematocrit testing procedures.

Hematocrit and Blood Donation

Hematocrit levels play a crucial role in blood donation eligibility:

• Minimum hematocrit levels are required to ensure donor safety and blood product quality
• Regular blood donors should monitor their hematocrit levels to maintain eligibility
• Proper nutrition and iron supplementation may be necessary for frequent donors

Blood donation centers typically check hematocrit levels before each donation to ensure donor and recipient safety.

Hematocrit in Veterinary Medicine

Hematocrit testing is also valuable in veterinary medicine:

• It helps diagnose anemia and other blood disorders in animals
• Normal hematocrit ranges vary among different animal species
• Veterinarians use hematocrit results to guide treatment decisions for pets and livestock

Understanding species-specific hematocrit ranges is essential for accurate interpretation in veterinary practice.

Future Directions in Hematocrit Research

Ongoing research in hematocrit testing and interpretation includes:

• Developing more accurate reference ranges for diverse populations
• Exploring the relationship between hematocrit and various health outcomes
• Investigating the potential use of hematocrit as a biomarker for specific diseases
• Improving non-invasive hematocrit measurement techniques

These advancements may lead to more personalized and precise hematocrit testing and interpretation in the future.

Hematocrit Information | Mount Sinai

HCT

Hematocrit is a blood test that measures how much of a person’s blood is made up of red blood cells. This measurement depends on the number of and size of the red blood cells.

Blood transports oxygen and nutrients to body tissues and returns waste and carbon dioxide. Blood distributes nearly everything that is carried from one area in the body to another place within the body. For example, blood transports hormones from endocrine organs to their target organs and tissues. Blood helps maintain body temperature and normal pH levels in body tissues. The protective functions of blood include clot formation and the prevention of infection.

How the Test is Performed

A blood sample is needed.

How to Prepare for the Test

No special preparation is necessary for this test.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

The hematocrit is almost always done as part of a complete blood count (CBC).

Your health care provider may recommend this test if you have signs of or are at risk for anemia. These include having:

• Before and after major surgery
• Blood in your stools, or vomit (if you throw up)
• Chronic medical problems, such as kidney disease or certain types of arthritis
• During pregnancy
• Fatigue, poor health, or unexplained weight loss
• Headaches
• Heavy menstrual periods
• Leukemia or other problems in the bone marrow
• Monitoring during treatment for cancer
• Monitoring medicines that may cause anemia or low blood counts
• Monitoring of anemia and its cause
• Poor nutrition
• Problems concentrating

Normal Results

Normal results vary, but in general they are:

• Male: 40. 7% to 50.3%
• Female: 36.1% to 44.3%

For babies, normal results are:

• Newborn: 45% to 61%
• Infant: 32% to 42%

The examples above are common measurements for results of these tests. Normal value ranges vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your provider about the meaning of your specific test results.

What Abnormal Results Mean

Low hematocrit may be due to:

• Anemia
• Bleeding

• Bone marrow being unable to produce new red blood cells. This may be due to leukemia, other cancers, drug toxicity, radiation therapy, infection, or bone marrow disorders 

• Chronic illness
• Chronic kidney disease
• Destruction of red blood cells (hemolysis)
• Leukemia
• Malnutrition
• Too little iron, folate, vitamin B12, and vitamin B6 in the diet
• Too much water in the body

High hematocrit may be due to:

• Bone marrow disease that causes abnormal increase in red blood cells (polycythemia vera)
• Congenital heart disease
• Exposure to high altitude
• Failure of the right side of the heart
• Low levels of oxygen in the blood
• Scarring or thickening of the lungs
• Too little water in the body (dehydration)

Risks

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.

Other risks associated with having blood drawn are slight but may include:

• Excessive bleeding
• Fainting or feeling lightheaded
• Multiple punctures to locate veins
• Hematoma (blood buildup under the skin)
• Infection (a slight risk any time the skin is broken)

Chernecky CC, Berger BJ. H. Hematocrit blood. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier Saunders; 2013:620-621.

Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM. Blood disorders. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 124.

Means RT. Approach to the anemias. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 26th ed. Philadelphia, PA: Elsevier; 2020:chap 149.

Vajpayee N, Graham SS, Bem S. Basic examination of blood and bone marrow. In: McPherson RA, Pincus MR, eds. Henry’s Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 31.

Last reviewed on: 1/9/2022

Reviewed by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

Hematrocit Blood Test – Testing.com

Test Quick Guide

Blood is made up of red blood cells (RBC), white blood cells (WBC), and platelets which are suspended in a liquid called plasma. A hematocrit (HCT) lab test determines the percentage of the blood that is composed of RBC.

An HCT test helps your medical provider screen for, diagnose, and monitor conditions that affect your blood or bone marrow. A measurement of HCT is routinely included in a complete blood count (CBC) but may also be ordered on its own if your provider suspects a condition affecting your RBC.

About the Test

Purpose of the test

The purpose of an HCT test is to evaluate the percentage of blood that is made up of RBC. This measurement indicates the viscosity, or thickness, of the blood and depends on the size and number of RBCs in a blood sample. HCT is most often evaluated as part of a CBC, which also includes measurements of RBC, WBC, platelets, and hemoglobin.

Often ordered during a routine medical check-up, a CBC is a common lab test. A CBC that includes HCT may also be ordered to evaluate the cause of certain symptoms, monitor patients receiving medical treatments, and track those with chronic health issues that affect the blood.

What does the test measure?

HCT measures the proportion of the blood that is composed of RBC and is expressed as a percentage.

RBCs are critical for the distribution of oxygen to the body’s cells. Once oxygen is used by cells to produce energy, RBCs transport the waste product, carbon dioxide, from the cells back to the lungs.

HCT levels can be affected by an increase or decrease in the number of RBCs and by changes in other components of the blood. Because HCT measures the percentage of RBC in the blood, relative increases or decreases in other blood components, like plasma or WBC, can lead to abnormal HCT results even if the RBC count is normal.

When should I get this test?

Your provider may test HCT as part of a CBC or if you are experiencing symptoms of an RBC disorder such as anemia. Indications for testing HCT include:

• Fatigue
• Moodiness
• Headaches
• Brain fog or difficulty concentrating
• Heavy menstrual flow
• Poor nutrition
• Blood in your stools or vomit
• Cancer and cancer treatment
• Excessive diarrhea or vomit
• Leukemia or other conditions associated with bone marrow
• Chronic health conditions, including kidney diseases

Finding an HCT Test

How can I get an HCT test?

An HCT test requires a sample of blood and is typically ordered by a doctor. A blood draw, also called venipuncture, is conducted by a health provider or a laboratory technician in a medical setting.

Can I take the test at home?

HCT testing is not usually performed at home. Conducting this test requires specialized tools and trained laboratory personnel.

How much does the test cost?

The cost of an HCT test depends on several factors, including other tests performed at the same time and whether or not you have health insurance or are paying out-of-pocket. The cost of HCT testing is often covered by insurance due to the routine nature of the test.

Refer to your health care provider, medical facility, or insurance company for specific details on costs, copays, and deductibles.

Taking an HCT Test

A blood sample is needed for HCT testing. To collect a blood sample, a needle is inserted into your arm and a vial, also known as a vacutainer, is placed on the provider’s end of the needle. The vial is then filled with blood that is used to test your hematocrit.

Before the test

There is no special preparation needed prior to an HCT test, unless specified by your provider.

During the test

Blood draws are a common medical procedure. Usually, blood is drawn from either the top of the hand or the vein on the inside of the elbow. To conduct a blood draw:

1. An antiseptic wipe is used to cleanse the area prior to the blood draw.
2. A band is placed around your arm to increase pressure in your vein, making your vein more visible and easier to access.
3. A needle is placed in your vein and a test tube is attached to the needle and filled with blood.
4. If you are getting other blood tests in addition to an HCT test you may have more than one vial of blood drawn.

After the test

Once the blood is drawn, the nurse or phlebotomist may ask you to hold pressure on the site of the venipuncture with a cotton swab for a few minutes. They may place a bandage on the cotton swab to maintain pressure.

After any blood draw, you will want to watch out for temporary side effects such as dizziness or lightheadedness. Your provider may want you to stay seated for a few minutes until they can determine that you are safe to get up and walk or drive.

Other than possible lightheadedness and bruising at the site where blood was drawn, there are few potential side effects from a blood draw.

HCT Test Results

Receiving test results

After the test is complete, results will be sent to your doctor for interpretation. HCT test results are most often part of the results of a CBC, which may be available to your doctor within a few minutes or up to several days.

Interpreting test results

HCT test results depend on several factors, including age and sex. The cutoff values for a normal test result, called its reference range, may also vary depending on the laboratory or methods used to conduct the test. Because of the many factors that affect HCT, it’s important to talk to a doctor for support in understanding your test result.

The reference ranges listed below describe common reference ranges for hematocrit:

Hematocrit Reference Ranges for Adults

An abnormal HCT level can indicate that your blood is either too thin or too thick compared to an average person of a similar population.

An abnormally low level of HCT indicates that your cells may not be getting enough oxygen, a condition known as anemia. Abnormally low HCT may be related to a variety of causes, including:

• Loss of blood
• Poor nutrition with low intake of iron, vitamin B6, vitamin B12 or folate
• Bone marrow disorders or cancers such as leukemia, lymphoma, multiple myeloma, or other cancers that spread to the marrow
• Destruction of RBCs
• Excessive water in the body

High HCT levels indicate conditions where there is either an overproduction of RBC or an abnormally high concentration of RBCs in your body. Some examples of causes of a high HCT include:

• Dehydration
• Lung disease
• Congenital heart disease
• Heart failure
• Certain types of kidney tumors
• Smoking
• Living at high altitudes
• Secondary polycythemia, a rare group of blood disorders caused by heritable changes to genes involved in the production of RBCs causing the body to produce too many RBCs
• Polycythemia vera, a rare blood disease in which the body produces too many RBCs

Although the results are accurate, laboratory parameters and provider reference ranges as well as personal variables may be subject to differences.

Abnormal HCT test results may or may not require additional follow-up testing. HCT is often evaluated alongside other components of a CBC to look for signs of disease or monitor health conditions.

For example, a doctor may order additional testing if you have low HCT to evaluate the cause of anemia. Testing for anemia may include a reticulocyte count, a renal panel, a liver panel, hemolysis testing, or a blood smear.

Follow-up testing is based on your symptoms, medical history, and the results of other tests. For questions about follow-up testing, speak with your doctor.

Talking with your doctor can help you understand your HCT result and any next steps. You may wish to ask the following questions:

• What does my result mean for my health?
• Is there anything I can do to change my HCT levels?
• Is there any further testing that needs to be done based on my HCT levels?

Resources

• CBC Blood Test (Complete Blood Count)
  Learn More
• Red Blood Cell Count (RBC) Test
  Learn More
• Hemoglobin Blood Test
  Learn More
• White Blood Cell Count (WBC Blood Test)
  Learn More
• Platelet Count (PLT) Blood Test
  Learn More
• Blood Smear
  Learn More
• Iron Test
  Learn More
• National Heart, Lung, and Blood Institute: Anemia
  Learn More
• National Heart, Lung and Blood Institute: Thalassemias
  Learn More

Sources

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Deciphering a blood test on the analyzer – Article in Yekaterinburg

Modern hematological analyzers have the ability to decipher from 5 to 24 blood parameters:

• WBC (white blood cells – white blood cells, leukocytes). The indicator characterizes the absolute content of leukocytes.
• RBC (red blood cells – red blood cells, erythrocytes) shows the absolute content of erythrocytes in the blood.
• HGB (Hb, hemoglobin, hemoglobin) – the concentration of hemoglobin in whole blood.
• HCT (hematocrit, hematocrit). Hematocrit determines the ratio of the volume of formed elements to plasma.
• PLT (platelets, platelets) – absolute number of platelets

Erythrocyte indices Using the analysis, you can determine the presence of microcytosis, normocytosis, macrocytosis.