What is hematocrit and why is it important. How is a hematocrit test performed. What do normal hematocrit levels look like. What can cause low hematocrit counts. How does hematocrit relate to overall health.

What is Hematocrit and Its Significance in Blood Composition

Hematocrit, often abbreviated as HCT, is a crucial blood test that measures the proportion of red blood cells in a person’s blood volume. This measurement provides valuable insights into the blood’s capacity to transport oxygen and nutrients throughout the body. The hematocrit level depends on both the number and size of red blood cells present in the bloodstream.

Understanding hematocrit is essential because blood plays a multifaceted role in maintaining overall health. It serves as a transport system for oxygen, nutrients, hormones, and waste products. Additionally, blood helps regulate body temperature, maintain pH levels in tissues, and provides protective functions such as clot formation and infection prevention.

Key Functions of Blood in the Human Body

• Oxygen and nutrient transportation
• Waste and carbon dioxide removal
• Hormone distribution
• Temperature regulation
• pH balance maintenance
• Clot formation
• Infection prevention

The Hematocrit Test: Procedure and Preparation

How is a hematocrit test conducted? The process is relatively simple and requires a blood sample. A healthcare professional will draw blood from a vein, typically in the arm, using a needle. This sample is then analyzed to determine the proportion of red blood cells.

Is special preparation needed for a hematocrit test? Fortunately, no specific preparation is necessary. Patients can proceed with their normal daily activities before the test. However, it’s always advisable to inform your healthcare provider about any medications or supplements you’re taking, as these may influence the results.

What to Expect During the Test

The experience of having blood drawn for a hematocrit test varies from person to person. Some individuals may feel moderate pain when the needle is inserted, while others might only experience a slight prick or stinging sensation. After the procedure, there may be some throbbing or a minor bruise at the insertion site, but these effects typically subside quickly.

Reasons for Performing a Hematocrit Test

Why would a healthcare provider recommend a hematocrit test? This test is almost always part of a complete blood count (CBC) and is often prescribed when there are signs or risk factors for anemia. Various conditions and symptoms may prompt a healthcare provider to order this test.

Common Indications for Hematocrit Testing

• Fatigue or unexplained weight loss
• Signs of blood loss (in stool or vomit)
• Chronic medical conditions (e.g., kidney disease, certain types of arthritis)
• Pregnancy monitoring
• Pre- and post-operative assessment
• Evaluation of heavy menstrual periods
• Monitoring during cancer treatment
• Assessment of nutritional status
• Investigation of concentration problems

Understanding Normal Hematocrit Ranges

What constitutes a normal hematocrit level? Normal ranges can vary slightly between laboratories, but general guidelines exist for different age groups and genders. It’s important to note that these ranges are averages, and individual results should be interpreted by a healthcare professional.

Typical Hematocrit Ranges

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

Why do hematocrit levels differ between males and females? This variation is primarily due to hormonal differences. Testosterone, more prevalent in males, stimulates red blood cell production, leading to higher hematocrit levels. Conversely, females tend to have lower hematocrit levels due to iron loss during menstruation and the effects of estrogen on red blood cell production.

Causes and Implications of Low Hematocrit Counts

A low hematocrit count can be indicative of various health issues. Understanding these potential causes is crucial for proper diagnosis and treatment. What are the common reasons for a low hematocrit level?

Potential Causes of Low Hematocrit

• Anemia
• Bleeding (acute or chronic)
• Bone marrow disorders
• Chronic illnesses
• Chronic kidney disease
• Hemolysis (destruction of red blood cells)
• Leukemia
• Malnutrition
• Nutritional deficiencies (iron, folate, vitamin B12, vitamin B6)
• Overhydration

How does anemia relate to low hematocrit? Anemia, a condition characterized by a lack of healthy red blood cells, is one of the most common causes of low hematocrit. It can result from various factors, including iron deficiency, chronic diseases, or inherited disorders affecting red blood cell production or survival.

The Impact of Chronic Conditions on Hematocrit Levels

Chronic medical conditions can significantly influence hematocrit levels. How do these long-term health issues affect red blood cell production and hematocrit? Conditions such as kidney disease, certain types of arthritis, and other inflammatory disorders can interfere with the body’s ability to produce red blood cells or lead to their premature destruction.

Chronic Kidney Disease and Hematocrit

Why does chronic kidney disease often lead to low hematocrit? The kidneys play a crucial role in producing erythropoietin, a hormone that stimulates red blood cell production. In chronic kidney disease, this function is impaired, leading to reduced red blood cell production and consequently, lower hematocrit levels.

Nutritional Factors Affecting Hematocrit

Diet plays a significant role in maintaining healthy hematocrit levels. What nutrients are essential for optimal red blood cell production? Key nutrients include iron, folate, vitamin B12, and vitamin B6. Deficiencies in these nutrients can lead to reduced red blood cell production or abnormal cell formation, resulting in lower hematocrit levels.

The Role of Iron in Hematocrit

Why is iron particularly crucial for maintaining normal hematocrit levels? Iron is a fundamental component of hemoglobin, the protein in red blood cells responsible for oxygen transport. Without sufficient iron, the body cannot produce enough healthy red blood cells, leading to iron-deficiency anemia and low hematocrit.

Importance of B Vitamins

How do B vitamins contribute to healthy hematocrit levels? Vitamins B12, B6, and folate are essential for the proper formation of red blood cells. Deficiencies in these vitamins can lead to megaloblastic anemia, characterized by the production of larger but fewer red blood cells, affecting the overall hematocrit.

Hematocrit in Pregnancy and Women’s Health

Pregnancy and menstruation can significantly impact a woman’s hematocrit levels. Why is hematocrit monitoring particularly important during pregnancy? During pregnancy, a woman’s blood volume increases to support the growing fetus, which can lead to a relative decrease in hematocrit. Additionally, the increased iron demands of pregnancy can sometimes lead to iron-deficiency anemia if not properly managed.

Menstruation and Hematocrit

How does menstruation affect hematocrit levels in women? Regular menstrual blood loss can lead to iron deficiency over time, especially in women with heavy periods. This chronic blood loss can result in lower hematocrit levels and potentially lead to anemia if not addressed.

Maintaining optimal hematocrit levels is crucial for overall health and well-being. Regular monitoring, especially for those with chronic conditions or specific risk factors, can help identify and address potential issues early. A balanced diet rich in iron and B vitamins, along with appropriate medical care, can support healthy hematocrit levels and ensure efficient oxygen transport throughout the body.

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.

What it is, levels, high and low range

Hematocrit is the percentage of red blood cells in a person’s blood. A typical hematocrit range in healthy adults is 37–52%. This varies depending on a person’s sex and age.

Authors of a 2017 study identified the above typical range.

Low red blood cell levels indicate conditions such as anemia. High red blood cell levels could signal polycythemia, increasing a person’s chance of developing a blood clot.

If a person feels tired, dizzy, or short of breath, a doctor may want to test their hematocrit levels to see if those levels fall into a normal range or not.

Read on to learn more about what this measure of red blood cell volume means, symptoms of abnormal levels, and what low and high levels might indicate.

Hematocrit measures the percentage of red blood cells in the body. For example: if a person has 50 milliliters (ml) of red blood cells in 100 ml of blood, their hematocrit level is 50%.

Red blood cells transport oxygen around the body and give blood its characteristic red color. In addition to oxygen, they also contain hemoglobin, a protein that binds to oxygen molecules. This allows red blood cells to pick up oxygen from the lungs and deliver it throughout the body.

An adequate amount of red blood cells is essential to keep the body’s processes running smoothly.

Many conditions can affect red blood cell production or its life cycle. This can make it difficult for a medical professional to diagnose these conditions. A doctor will use a hematocrit test to confirm whether a person’s red blood cell count is affecting a health condition.

Doctors usually test hematocrit levels as part of a complete blood count (CBC).

A CBC is composed of a range of tests and may include:

• red blood cell count
• reticulocyte count (young red blood cells)
• an analysis of hemoglobin levels
• an analysis of red blood cells, including size and shape
• white blood cell tests
• platelet tests

A doctor will also consider a person’s sex, race, and age. It is important to note that certain blood-related conditions, such as sickle-cell anemia, affect particular demographic groups at higher rates.

Learn more about sickle cell anemia in African Americans here.

A doctor may request frequent hematocrit tests to monitor the effect of chemotherapy on a person’s bone marrow.

Both high and low hematocrit levels can be detrimental to a person’s health and result from various conditions and lifestyle factors.

What are normal hematocrit levels?

Different institutions will define normal hematocrit levels differently. However, a 2017 cross-population study found the following ranges to be typical.

• Male: 42-52%
• Female: 37-47%
• Children: 30–44%, depending on their age and sex

Newborn babies have high hematocrit levels that gradually decrease as they get older.

If a person has recently received a blood transfusion, it may affect their results. Additionally, pregnant individuals may have lower levels than usual because the body increases its blood volume during pregnancy.

Other factors, such as smoking and chronic obstructive pulmonary disease (COPD), may push levels into a higher range.

Low levels

A hematocrit level below 35% in women and 41% in men is low. A level under this value can signify chronic anemia.

High levels

Hematocrit levels above the typical ranges can have adverse effects. It may indicate serious underlying health conditions.

Accuracy of results

Results from hematocrit tests are typically accurate and provide a clear reading of a person’s red blood cell levels.

However, the percentage of red blood cells in someone’s blood can change depending on various lifestyle factors and even environmental changes. According to research, red blood cell counts tend to increase at high altitudes.

Exercise, particularly strength training, may also affect hematocrit levels. A 2018 study found that females who participated in 16 weeks of strength exercise had lower levels at the end than when they started. However, the study had a small sample size of 26 middle-aged, sedentary Turkish women. This means that these findings aren’t necessarily representative of a wider population.

Dehydration can also raise hematocrit levels, so this test is useful if a doctor suspects severe dehydration is the cause of a person’s symptoms.

When a person has low hematocrit levels, they tend to present with the following symptoms:

• pale complexion
• weakness
• fatigue
• low energy
• trouble breathing
• irregular heartbeat
• cold hands or feet

These symptoms also indicate anemia, a condition where hemoglobin levels are lower than normal. Hemoglobin is a protein found in red blood cells that carries oxygen around the body.

Mild anemia is treatable, and it is particularly common in women. Severe anemia could signal a more serious underlying health condition that requires more extensive treatment.

Doctors associate anemia with several health conditions, including:

Nutrient deficiency

A person may lack B12, folate, or iron in their diet.

Learn more about how nutrient deficiency anemia is diagnosed and treated.

Chronic bleeding

This commonly occurs due to digestive tract ulcers, which are sores caused by the bacteria H.pylori or chronic use of anti-inflammatory medications such as ibuprofen, other nonsteroidal anti-inflammatory drugs (NSAIDs), and aspirin. Many women also experience excessive blood loss from heavy menstrual bleeding.

Bone marrow disorder

This includes aplastic anemia, which damages stem cells in bone marrow.

Cancer

These cancers spread to bone marrow, such as leukemia and lymphoma.

Learn more about bone marrow cancers here.

Kidney failure

Kidney disease can lower the production of red blood cells, reducing hematocrit levels.

Thalassemia

When a person has this condition, their body does not produce enough hemoglobin.

Learn more about thalassemia here.

Sickle cell anemia

This condition changes the shape of red blood cells. These cells die earlier than normal, and they also clump together, which impairs blood flow.

Learn more about sickle cell anemia here.

Autoimmune disease

Conditions like rheumatoid arthritis and lupus may reduce red blood cell count.

Learn more about autoimmune diseases here.

When a person has high hematocrit levels, they tend to present with these symptoms:

• flushed skin
• dizziness
• vision problems
• headaches
• enlarged spleen

These symptoms signal polycythemia, a condition where the body produces too many red blood cells. This means blood is thicker and clots more easily.

Doctors cannot cure polycythemia, so treatment focuses on symptom management. The main goal is to avoid stroke and deep vein thrombosis (DVT), which is a blood clot usually occurring in a deep vein in the leg.

In some cases, dehydration causes polycythemia. When a person does not drink enough, their plasma levels drop, increasing the proportion of red blood cells in their blood volume. A person can lower their red blood cell count by rehydrating.

Some conditions that can cause high hematocrit levels include:

Lung or pulmonary disease

When the lungs cannot absorb oxygen effectively, and oxygen levels drop, the body compensates by making more red blood cells. One common pulmonary disease causing this is COPD.

Learn more about COPD here.

Heart disease

If the structure of a person’s heart reduces its ability to pump blood around the body, it can no longer sustain vital organs with oxygen. To try and overcome the oxygen deficit, the body produces more red blood cells.

Learn more about heart disease here.

Kidney cancer

Sometimes kidney cancer cells create more erythropoietin. Erythropoietin is a hormone that tells the bone marrow to create more red blood cells.

Learn more about kidney cancer here.

Genetic disease

The JAK2 gene, which controls the number of blood cells made in the bone marrow, can affect certain conditions. When someone has a mutated JAK2 gene, the body could make a protein that signals the bone marrow to create more red blood cells than it needs.

Learn more about genetic disorders here.

A person should speak with a doctor if they are experiencing any of the symptoms listed above that could be a sign of high or low hematocrit levels, including fatigue, weakness, vision problems, and dizziness.

These symptoms can also indicate an underlying condition, so a person must contact a doctor promptly to prevent future complications.

If a person is receiving chemotherapy treatment, a doctor should perform regular hematocrit tests to monitor bone marrow health.

Hematocrit is the percentage of blood cells in a person’s blood volume. A doctor may test an individual’s hematocrit level due to certain symptoms.

A low hematocrit level means there are too few red blood cells in the body. In these cases, a person may experience symptoms that signal anemia. Common symptoms include fatigue, weakness, and low energy.

If a person has too many red blood cells, they have a high hematocrit level. A person may experience dizziness and headaches, which can be a sign of the condition polycythemia.

Demographic and lifestyle factors can influence a person’s hematocrit levels. For example, males tend to have higher levels than females. Pregnant individuals can experience a decrease in hematocrit levels, and strength training may also reduce levels.

There are also several health conditions that can cause hematocrit levels outside the normal range. Excessive bleeding, thalassemia, and kidney disease are causes of low levels. COPD and sickle cell anemia can cause high levels.

Read this article in Spanish.

norm in a child, women, men, causes of increased, decreased values ​​in the blood

Hematocrit is one of the blood indicators that registers the total volume of all formed elements, and these are erythrocytes, leukocytes and platelets, in relation to the total volume. Moreover, 99% of the volume of all these elements falls on erythrocytes. The hematocrit (Ht) is expressed as a percentage, but a liter per liter (L/L) can also be selected.

Human blood contains from 36 to 48% of formed elements, it also contains plasma, water, proteins, carbohydrates and salts.

Hematocrit is determined simply: a certain amount of blood is poured into a special tube with graduation, then it is sent to a centrifuge, and at the end of the process, the fraction of the length of the tube that was filled with erythrocyte mass is determined. Also, laboratories now use automatic hematology analyzers that allow you to get data in just a few minutes.

Blood hematocrit norm

The body of an adult healthy person contains about 5 liters of blood. Erythrocytes, leukocytes and platelets cannot be called cells, they do not have the necessary parameters for this. Therefore, they are called formed elements. Different people have different amounts of these elements per liter of blood. For example, according to statistics, the hematocrit in men is higher and equal to 40-41%, sometimes this figure can reach 51%.

Hematocrit in women is slightly lower and usually ranges from 36-42%. The reason for this is such a physiological feature as menstruation. As for the period of pregnancy, here this figure begins to decrease in the second half, and this is also not a pathology.

Hematocrit in children always depends on age, therefore, before drawing conclusions from the analysis, it is necessary to find out how many months or years the baby is. In newborn babies, this figure can be equal to 44-62%, at the age of 3 months it decreases and the figure becomes up to 44%, from 3 months to 1 year the figures can range from 32 to 43%. In the first ten years, Ht in boys can rise to 52%, and in girls it can be at around 35-47%. In subsequent years, the hematocrit norm is equal to the same indicator that is recorded in adults.

Causes of increased hematocrit

Why can it happen that the hematocrit in the blood test is elevated? There are pathological and physiological causes, so before starting any treatment, it is important to understand their origin.

Pathological causes include the following diseases and conditions:

1. Dehydration (dehydration). Due to the fact that the amount of blood that circulates through the vessels decreases, the formed elements are in a more concentrated state. This happens with vomiting, diarrhea, heavy sweating, overheating, lack of fluid.
2. Second and third degree burns. In this case, blisters appear on the body, which are filled with plasma, and it appeared in them from the bloodstream. Therefore, the blood becomes thicker, and the concentration of formed elements increases.
3. Peritonitis, thrombosis or diabetes mellitus.
4. Chronic hypoxia.
5. Regular use of glucocorticosteroids or diuretics.
6. Kidney disease – hydronephrosis.
7. Almost all blood diseases, including leukemia.
8. Polycystic.
9. Heart defects, ischemic heart disease.
10. Erythremia.
11. Many lung diseases, including asthma, bronchitis.
12. Severe bleeding.

However, hematocrit analysis alone is not enough to make an accurate diagnosis, it is not very informative. Therefore, it is often done as part of a general blood test, and further therapy tactics are already built on it, if it turns out to be necessary.

But elevated hematocrit can also be the result of certain physiological phenomena. In this case, deviations of this indicator cannot be considered pathological. High Ht in comparison with the norm is detected in people who smoke constantly and for a long time, which is associated with the development of chronic oxygen starvation of tissues and increased production of red blood cells.

Residents of high mountain regions and mountaineers who spend a lot of time at altitude also have Ht in the range of 51-52%. This is all connected with the same oxygen starvation and the need for the body to compensate for this lack. Also, elevated Ht is typical for athletes who take anabolics that help them gain the required amount of muscle mass.

Manifestations and symptoms of elevated hematocrit

If the hematocrit in the blood is elevated, then this will not necessarily be expressed by certain symptoms. However, it should be remembered that this condition is always expressed by an increase in blood viscosity, which creates a great threat for the formation of blood clots and clogging of both small and large vessels.

If this happens in the coronary arteries, then myocardial infarction develops against the background of thrombosis. If a thrombus forms in the pulmonary artery, then death occurs in 70% of all cases. If the arteries of the brain are affected, then this leads to the development of an ischemic stroke. With thrombosis of the vessels of the legs, gangrene begins to develop.

Therefore, it is important to find out the cause of elevated Ht as soon as possible and start timely treatment.

Reasons for low hematocrit

A decrease in hematocrit can occur without any pronounced symptoms, so this result is usually detected after a blood test and is an unexpected discovery for a person.

The main reasons why the hematocrit may be low are:

• virtually all anemias, including iron deficiency, folate deficiency, B12 deficiency;
• violation of the production of red blood cells due to pathologies of the bone marrow, including oncological ones;
• cirrhosis of the liver;
• diseases of the urinary system;
• hemolysis or destruction of red blood cells;
• chronic bleeding;
• increase in circulating blood volume;
• hyperproteinemia;
• lead intoxication;
• acute infections;
• the use of anticoagulants and similar drugs that affect the composition of the blood.

Decreased hematocrit may have physiological causes. This is work associated with a long stay in one position, starvation or adherence to strict diets, a large amount of fluid that enters the body, alcoholism, the use of large amounts of salt, the period of menstruation.

Manifestations and symptoms of low hematocrit

The reasons for the drop in hematocrit will directly affect what symptoms a person experiences. For example, if it is anemia, then there will be such complaints:

• headache and constant weakness;
• impaired consciousness and breathing;
• dizziness, nausea or vomiting;
• constant thirst;
• lack of strength and exercise intolerance.

If the cause is kidney and urinary system diseases, then there will be complaints about a decrease in the amount of urine excreted, pain in the lumbar region, urination disorder, and changes in blood pressure.

With cirrhosis of the liver, complaints will be of pain in the right side of the abdomen under the ribs, the appearance of spider veins on the skin, indigestion, excessive formation of gases, a feeling of fullness in the abdomen, in advanced cases – internal bleeding.

What tests are needed?

To find out the relative content of all formed elements in the blood, it is necessary to analyze the hematocrit. It is done as part of a general blood test (CBC), when, together with Ht, the number of all elements is calculated, and the ESR is also determined.

Usually, it is with the KLA that a patient’s examination begins to identify a particular disease, or it is carried out for preventive purposes as part of a medical examination, medical examination.

Both venous blood and capillary fingerstick blood can be used for analysis. It is best to take the test in the morning, before breakfast. This allows you to get the right readings that will help the doctor determine if Ht is elevated or low, or its values ​​are within the normal range.

Hematocrit

Hematocrit is the ratio of the volume of erythrocytes to the volume of the liquid part of the blood.

Determination of hematocrit is an integral part of the general blood test and is not performed separately.

Synonyms Russian

Hematocrit value.

Synonyms English

Ht, Hct, Hematocrit, Crit, Haematocrit, PCV, Packed Cell Volume.

Units

% (percentage).

What biomaterial can be used for research?

Venous blood.

General information about the study

Hematocrit determines the amount of blood occupied by red blood cells in the bloodstream. This indicator is expressed as a percentage. For example, a hematocrit of 45% means that 100 milliliters of blood contains 45 milliliters of red blood cells.

An increase in hematocrit occurs if the number of red blood cells increases or the volume of the liquid part of the blood decreases, which happens when the body loses excess fluid (for example, with diarrhea). A decrease in this indicator is observed, on the contrary, with a decrease in the number of red blood cells (for example, due to their loss, destruction, or a decrease in their formation) or with overhydration – when a person receives too much fluid (for example, with excessive administration of intravenous solutions).

Hematocrit reflects not only the number of red blood cells, but also their size. If the size of red blood cells decreases (as in iron deficiency anemia), the hematocrit will also decrease.

What is research used for?

• In the diagnosis of anemia and polycythemia and to evaluate the effectiveness of their treatment.
• To determine the degree of dehydration.
• As one of the criteria for deciding on the need for a blood transfusion.
• To evaluate the effectiveness of blood transfusions.

When is the examination scheduled?

This test is part of a routine complete blood count, which is performed both routinely and in various diseases and pathological conditions, before surgical interventions.

In addition, it can be carried out repeatedly and at certain intervals:

• with dynamic monitoring and evaluation of the effectiveness of the treatment of anemia and polycythemia,
• after conditions causing dehydration,
• for recurrent bleeding for a comprehensive assessment of their severity.

What do the results mean?

Reference values ​​

Generally, the hematocrit corresponds to the number of red blood cells, but this is only true when the size of the red blood cells is normal. If the number of normal-sized red blood cells increases, the hematocrit also rises. In cases of large or small erythrocytes, this is not always the case. For example, with iron deficiency, red blood cells decrease and the hematocrit will be reduced, but the number of red blood cells per unit of blood may be normal and even slightly higher.

Hematocrit level above 55% requires clarification of the cause and further diagnostic search.

Causes of low hematocrit:

• iron-, B ₁₂ – or folic deficiency anemia,
• acute or chronic bleeding (during or immediately after bleeding, hematocrit and hemoglobin will be elevated),
• disorders of hemoglobin synthesis (sickle cell anemia, thalassemia),
• cirrhosis of the liver,
• destruction of erythrocytes as a result of hemolysis – destruction of erythrocytes inside the body (it can occur for various reasons – due to a hereditary defect in erythrocytes, as a result of the appearance of antibodies to one’s own erythrocytes or toxic effects in malaria),
• oncological diseases of the bone marrow or metastases of other tumors in the bone marrow, leading to a decrease in the synthesis of red blood cells,
• excessive hydration of the body – the introduction of large volumes of intravenous fluids.

Causes of increased hematocrit:

• dehydration (dehydration) of any origin – due to diarrhea, profuse vomiting, diabetes, after burns,
• polycythemia vera due to excessive production of red blood cells in the bone marrow,
• chronic obstructive pulmonary disease,
• chronic heart failure.

What can influence the result of ?

1. The hematocrit level is normally reduced in pregnant women due to a physiological increase in the volume of the liquid part of the blood.
2. Persons ascending to high altitudes experience an increase in the number of red blood cells and, consequently, hematocrit, as their body adapts to the reduced oxygen concentration.
3. Hematocrit may be increased in smokers due to oxygen deprivation of tissues and increased production of red blood cells.
4. In newborns, the hematocrit level is increased, since they have quite a lot of large red blood cells in their blood.