What is hematocrit and why is it important in blood work. How is the hematocrit test performed and what do the results mean. What factors can affect hematocrit levels and when should you be concerned.

What is Hematocrit (HCT) and Its Significance in Blood Work?

Hematocrit (HCT) is a crucial component of blood work that measures the proportion of red blood cells in a person’s blood volume. This test provides valuable insights into an individual’s overall health and can indicate various medical conditions.

The hematocrit test is typically part of a complete blood count (CBC) and is expressed as a percentage. It reflects both the number and size of red blood cells in the bloodstream.

Why is Hematocrit Important?

• Assesses oxygen-carrying capacity of blood
• Helps diagnose anemia and other blood disorders
• Monitors overall health and hydration status
• Aids in evaluating response to certain treatments

Understanding your hematocrit levels can provide crucial information about your body’s ability to transport oxygen and maintain proper blood volume.

The Hematocrit Test Procedure: What to Expect

The hematocrit test is a simple and routine blood test that requires minimal preparation. Here’s what you can expect during the procedure:

1. A healthcare professional will clean the area, usually your arm, with an antiseptic.
2. A tourniquet may be applied to make your veins more visible.
3. A needle will be inserted into your vein to draw a small amount of blood.
4. The blood sample is collected in a vial or tube.
5. The needle is removed, and pressure is applied to stop any bleeding.

The entire process typically takes only a few minutes. While some individuals may experience slight discomfort or bruising at the site of the blood draw, serious complications are rare.

Is special preparation required for a hematocrit test?

Generally, no special preparation is necessary for a hematocrit test. However, your healthcare provider may give you specific instructions based on your individual circumstances or if other tests are being performed simultaneously.

Interpreting Hematocrit Results: Normal Ranges and Variations

Hematocrit results are typically expressed as a percentage of total blood volume. Normal ranges can vary slightly between laboratories and may differ based on factors such as age, sex, and overall health status.

What are the normal hematocrit ranges?

• Adult males: 40.7% to 50.3%
• Adult females: 36.1% to 44.3%
• Newborns: 45% to 61%
• Infants: 32% to 42%

It’s important to note that these ranges are general guidelines. Your healthcare provider will interpret your results in the context of your overall health, symptoms, and other test results.

Can hematocrit levels fluctuate?

Yes, hematocrit levels can fluctuate due to various factors, including:

• Altitude: People living at high altitudes may have higher hematocrit levels
• Dehydration: Can temporarily increase hematocrit
• Pregnancy: Levels may decrease during pregnancy
• Exercise: Intense physical activity can cause short-term changes
• Time of day: Slight variations can occur throughout the day

These fluctuations highlight the importance of considering multiple factors when interpreting hematocrit results.

Low Hematocrit: Causes, Symptoms, and Implications

A low hematocrit, also known as anemia, can have various causes and may indicate underlying health issues. Understanding the potential reasons for low hematocrit can help in proper diagnosis and treatment.

What are common causes of low hematocrit?

• Iron deficiency
• Vitamin B12 or folate deficiency
• Chronic diseases (e.g., kidney disease, cancer)
• Blood loss (e.g., heavy menstrual periods, gastrointestinal bleeding)
• Bone marrow disorders
• Certain medications
• Pregnancy

Symptoms of low hematocrit may include fatigue, weakness, shortness of breath, pale skin, and dizziness. If you experience these symptoms, it’s essential to consult your healthcare provider for proper evaluation.

How is low hematocrit treated?

Treatment for low hematocrit depends on the underlying cause. Common approaches include:

• Iron supplementation
• Vitamin B12 injections
• Dietary changes
• Treating underlying conditions
• Blood transfusions in severe cases

Your healthcare provider will develop a personalized treatment plan based on the cause and severity of your low hematocrit.

High Hematocrit: Causes, Risks, and Management

Elevated hematocrit levels can indicate various conditions and may pose health risks if left untreated. Understanding the implications of high hematocrit is crucial for proper management and prevention of complications.

What can cause high hematocrit levels?

• Dehydration
• Polycythemia vera (a blood disorder)
• Chronic obstructive pulmonary disease (COPD)
• Heart disease
• Living at high altitudes
• Smoking
• Certain medications

High hematocrit can increase the risk of blood clots, which may lead to serious complications such as stroke or heart attack. Symptoms may include headaches, dizziness, and shortness of breath.

How is high hematocrit managed?

Management of high hematocrit typically involves addressing the underlying cause. Treatment options may include:

• Phlebotomy (removal of blood)
• Hydration
• Lifestyle changes (e.g., quitting smoking)
• Medications to reduce red blood cell production
• Treatment of underlying conditions

Regular monitoring and follow-up with your healthcare provider are essential for managing high hematocrit effectively.

The Role of Hematocrit in Diagnosing Blood Disorders

Hematocrit plays a crucial role in the diagnosis and monitoring of various blood disorders. By providing insights into the proportion of red blood cells in the blood, it helps healthcare providers identify potential issues and guide treatment decisions.

Which blood disorders can be detected through hematocrit testing?

• Anemia (various types)
• Polycythemia vera
• Leukemia
• Hemolytic disorders
• Thalassemia
• Sickle cell disease

While hematocrit is a valuable diagnostic tool, it is often used in conjunction with other blood tests and clinical evaluations to provide a comprehensive assessment of blood health.

How often should hematocrit levels be checked?

The frequency of hematocrit testing depends on individual circumstances. Factors that may influence testing frequency include:

• Age and overall health
• Presence of chronic conditions
• Medications that may affect blood cell production
• History of blood disorders
• Ongoing medical treatments (e.g., chemotherapy)

Your healthcare provider will recommend an appropriate testing schedule based on your specific needs and health status.

Hematocrit and Cardiovascular Health: Connections and Implications

The relationship between hematocrit levels and cardiovascular health is complex and multifaceted. Understanding this connection can provide valuable insights into overall heart health and potential risks.

How does hematocrit affect cardiovascular health?

• Blood viscosity: Higher hematocrit can increase blood thickness, potentially straining the heart
• Oxygen delivery: Optimal hematocrit ensures efficient oxygen transport to tissues
• Clotting risk: Elevated levels may increase the risk of blood clots
• Cardiac output: Hematocrit influences the heart’s pumping efficiency

Maintaining healthy hematocrit levels is crucial for optimal cardiovascular function and reducing the risk of heart-related complications.

Can hematocrit predict cardiovascular risk?

While hematocrit alone is not a definitive predictor of cardiovascular risk, it can be a valuable marker when considered alongside other factors. Research has shown that both high and low hematocrit levels may be associated with increased cardiovascular risk in certain populations.

Healthcare providers may consider hematocrit levels in conjunction with other cardiovascular risk factors to assess overall heart health and guide preventive strategies.

Lifestyle Factors Affecting Hematocrit Levels

Various lifestyle factors can influence hematocrit levels, either directly or indirectly. Understanding these factors can help individuals maintain healthy hematocrit levels and overall well-being.

Which lifestyle choices impact hematocrit?

• Diet: Iron-rich foods and proper nutrition support healthy red blood cell production
• Hydration: Adequate fluid intake helps maintain appropriate blood volume
• Exercise: Regular physical activity can influence hematocrit levels
• Smoking: Tobacco use can elevate hematocrit levels
• Alcohol consumption: Excessive alcohol intake may affect red blood cell production
• Stress management: Chronic stress can impact overall blood health

Making positive lifestyle choices can contribute to maintaining healthy hematocrit levels and supporting overall blood health.

How can you naturally improve your hematocrit levels?

If your hematocrit levels are low, consider these natural approaches to support healthy red blood cell production:

• Consume iron-rich foods (e.g., lean meats, leafy greens, legumes)
• Ensure adequate vitamin B12 and folate intake
• Stay hydrated
• Engage in regular moderate exercise
• Manage stress through relaxation techniques
• Avoid excessive alcohol consumption

Always consult with your healthcare provider before making significant changes to your diet or lifestyle, especially if you have underlying health conditions.

Understanding hematocrit and its role in overall health is crucial for maintaining well-being and identifying potential health issues early. By staying informed about factors that influence hematocrit levels and working closely with healthcare providers, individuals can take proactive steps to support optimal blood health and reduce the risk of associated complications.

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.