What It Means to Get High or Low Results > Personalabs

The hematocrit or HCT blood test measures the proportion of red blood cells to white blood cells, platelets, and plasma. 

High HCT blood test values (usually over 44% to 50%) indicate dehydration and conditions that cause RBC overproduction. Alternatively, extremely low hematocrit results may indicate anemia or other blood disorders that affect RBC formation (erythropoiesis) or destruction (hemolysis). 

Know more about the concerning levels of HCT and what the test results tell you when you read on.

Pro Tip: Hematocrit and other parts of the complete blood count (CBC) reveal essential information about your health. If you wish to learn more about what your blood test means, book a virtual consultation to speak to a healthcare provider. 

High HCT Meaning 

If your HCT blood test result shows high hematocrit, over 50% for men and 44% for women, it suggests that you have more red blood cells or erythrocytes due to an underlying health condition. It could also indicate that blood plasma is in critically low volume. 

Symptoms of high hematocrit include:

• Fatigue
• Dizziness 
• Headaches
• Vision problems
• Skin blushing or flushing

Causes of High HCT

Dehydration

If you have high HCT, you are likely to be dehydrated. In this case, you may not necessarily be producing too many RBCs. Instead, your blood has a low volume of plasma which stems from a lack of proper hydration. 

Lung Disease

Conditions affecting lung function, such as chronic obstructive pulmonary disease (COPD), can affect the organ’s ability to obtain oxygen. To compensate for the oxygen shortage, your body will produce more RBCs. If you have symptoms of pulmonary disorders, your doctor may order additional laboratory tests, including lung function blood tests. 

Heart Disease

People with heart disease are prone to high hematocrit and hemoglobin. As the heart cannot function fully to facilitate blood circulation, your body will counteract the said loss with increased erythrocyte production. Thus, an HCT blood test also provides additional information about your risk for cardiovascular diseases, making it a key part of heart health blood tests. 

Cancer

The primary cancer type that drives your bone marrow to produce excessive red blood cells is called polycythemia vera. Although extremely rare, this blood cancer slows down blood circulation, and leads to an enlarged spleen, increased blood clotting, and other life-threatening blood-related complications. Naturally, it also elevates your normal hematocrit levels. 

On the other hand, kidney cancer also influences erythrocyte production since it releases the protein (erythropoietin) that prompts the process. This can be further confirmed by additional tests, such as a red blood cell count, biopsy, MRI, etc. 

Did You Know? Several cancers can be detected by biomarkers screened through a blood test. In some cases, these cancers are first spotted through routine exams. Learn more about the types of cancer diagnosed through blood testing. 

Treatment for Elevated HCT

Lowering your high HCT will depend on its cause. For example, if it’s due to dehydration, your healthcare provider may recommend rehydration therapy. If your test result goes extremely above the normal range for HCT, your doctor may push for phlebotomy, wherein blood is extracted to reduce red blood cell count. 

Low HCT Meaning 

To get an HCT below the normal hematocrit range (less than 41% for men and 36% for women) indicates low red blood production or a high rate of destruction, potentially due to an underlying illness. 

The most common cause of low hematocrit is anemia, characterized by a reduced number of healthy red blood cells. You may spot anemia through the following symptoms:

• Fatigue
• Dizziness 
• Chest pain
• Headaches 
• Pale complexion
• Trouble breathing
• Cold hands and feet
• Irregular heartbeat (arrhythmia) 

Causes of Low HCT

Anemias 

As mentioned above, low HCT typically signals anemia, which can be due to a lack of nutrients, such as that in iron-deficiency anemia, or genetic factors like what’s causing sickle cell anemia and aplastic anemia. Additional blood tests are needed to verify the condition, including the anemia profile blood test. 

Blood Loss

Women who experience excessive menstrual bleeding are likely to have low HCT. In the same way, those who suffer from bacterial ulcers caused by H. pylori and other similar disorders leading to internal bleeding can also expect decreased HCT in their blood test. 

Did You Know? It’s possible to experience blood loss without seeing blood in your stool, as the naked eye does not easily detect it. Get the fecal occult blood test to determine if you have chronic digestive bleeding.

Thalassemia 

Thalassemia is an inherited blood disorder wherein your body fails to produce enough hemoglobin, a crucial protein in the red blood cell. As a result, RBCs are low, indicated by low HCT and erythrocyte count.  

Kidney Problems

Your kidneys don’t just filter wastes from the blood. They also produce the protein erythropoietin, which signals the production of RBCs. Hence, disorders like chronic kidney disease (CKD) and other significant kidney problems lead to low secretion of erythropoietin, resulting in inadequate RBCs. 

Inflammatory Diseases

Conditions like lupus and rheumatoid arthritis, characterized by increased inflammatory activities, negatively influence RBC formation and maturation. Similarly, inflammatory bowel disease (IBD) may also promote anemia leading to low HCT as it affects the absorption of iron, copper, vitamin B12, and other fundamental nutrients for erythropoiesis.  

Cancers

Leukemia and lymphoma are two types of cancers that directly impact bone marrow function. Hence, with these underlying conditions, you may likely get low HCT in your blood test and undergo further testing. 

Treatment for Low HCT

If low HCT is due to iron-deficiency anemia, your doctor may recommend supplements and certain lifestyle adjustments. Learn more about iron deficiency anemia and its physical impact, especially among women.  

On the other hand, if the condition is linked to more complex disorders like cancer, blood disease, CKD, etc., your healthcare provider will need more information to form an accurate diagnosis, entailing other types of assessment. Only then will your doctor prescribe a treatment that covers the process in which HCT is brought to its normal range.

How Is Hematocrit Measured?

Calculating hematocrit involves measuring the ratio of red blood cells through a reading device. When using a capillary tube, the length of the RBC packed length volume is compared to the total length of the blood sample. 

It is imperative to have the analysis within 10 minutes of the sample collection, as the erythrocyte layers can mix with the other blood components and platelets begin to clot. 

How and When Is It Done?

Your doctor will likely order an HCT blood test if you exhibit symptoms of anemia, blood loss, dehydration, and other blood disorders. As part of the CBC test, it also provides critical information on other disorders, such as cancer, lung disease, kidney disease, liver problems, and cardiovascular diseases.  

Unlike the other tests involved in CBC, wherein the blood samples can be collected through finger pricking, an HCT blood test will require a venous blood sample. This is drawn from the veins at the back of your elbow and should only be performed by a licensed phlebotomist. HCT measurement needs more volume of blood for accurate processing and analysis. 

Additionally, an HCT blood test alone does not require fasting or other special preparations prior to blood collection. But if it is part of a more extensive test or if you’re taking another test simultaneously, you may have to abstain from consuming food, drinks, and certain medications. 

Pro Tip: Venipuncture, the process of inserting a syringe needle into your vein for blood collection, can be a little discomforting. If you are anxious about your lab test appointment, read our tips on how to calm yourself when getting blood drawn. 

Frequently Asked Questions

What level of HCT is concerning?

The normal hematocrit range for men is 41% to 50%, while women should have 36% to 44%. HCT test values that go above or below these ranges signal problems in the blood ranging from anemia to blood loss for low HCT percentage and dehydration to blood cancer for high lab values. Either way, see your doctor for a proper diagnosis and additional lab tests. 

Can high HCT cause fatigue?

Feeling exhausted all the time is part of the symptoms of high HCT. The increased volume of RBCs causes the blood to be thicker and move slower, affecting the rate of oxygen distribution to cells. As a result, your brain receives less oxygen, making you tired and sleepy. 

Does low HCT mean dehydration?

It’s the other way around. Low HCT suggests conditions like anemia and other blood disorders, but it’s high HCT that indicates dehydration. The lack of sufficient fluid in your body results in blood plasma having less volume, which increases the percentage of RBC. 

Did You Know? Aside from an HCT blood test, other ways to detect dehydration include a urinalysis and the electrolyte blood test panel. Treatment for severe dehydration includes administering IV fluids and oral rehydration solution (ORS). 

The Bottom Line 

An HCT blood test helps detect various health conditions, especially blood disorders. However, without fully understanding what your test results mean may lead to misconceptions about the severity of the abnormality. In addition, it’s important to understand that a hematocrit blood test alone will not suffice as far as diagnosis goes. It’s always the best course of action to speak to your doctor whether by setting up an appointment, either for a physical or virtual consultation.

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.

Complete blood count

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).

Norm (NEUT): 40%-75% (number of neutrophils in 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 ) – 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. Sometimes a decrease in platelets can lead to the formation of blood clots.

( 7 votes )

everything for laptops
Bath and sauna accessories

Hematocrit

Hematocrit – 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.

Russian synonyms

Hematocrit value.

Synonyms English

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

Units

% (percentage).

Which biomaterial can be used for research?

Venous blood.

General information about the study

Hematocrit determines the volume 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 test scheduled?

This test is included in the routine complete blood count, which is carried out both planned and for various diseases and pathological conditions, before surgical interventions.

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

• for 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 levels will be elevated),
• disorders of hemoglobin synthesis (sickle cell anemia, thalassemia),
• cirrhosis of the liver,
• destruction of erythrocytes as a result of hemolysis – the 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, accordingly, hematocrit, as their body adapts to the reduced oxygen concentration.
3. Hematocrit may be increased in smokers due to oxygen starvation 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.