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Why low hct: Hematocrit Information | Mount Sinai

Hematocrit Information | Mount Sinai


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)


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.


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.


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.

Automatic blood test – normal values ​​of erythrocyte levels – Article in Yekaterinburg

Traditional manual and modern automated methods used in hematological studies differ in results. This is due to their metrological differences. The following are the values ​​that can be obtained from laboratory tests in various groups of patients.

Hemograms obtained from the use of hematology analyzers in adult patients.

90 009 32 – 37 g/dl

9 0021

Parameter Women Men RBC) 3. 8 – 5.1 t/l* 4.3 – 5.7 t/l l*
Hemoglobin (HGB) 117 – 160 g/l 131 – 173 g/l
Hematocrit (HCT) 35 – 45% 39 – 50%
MCV 80 – 100 fl* 80 – 100 fl*
MCH 27 – 34 pg* 27 – 34 pg*
MCHC 32 – 36 g/dl
RDW 11.6 – 14.8% 11.6 – 14.8%
Platelets (PLT) 150 – 400 G/L* 150 – 400 G/L*
Leukocytes (WBC)** 3.5 – 11.0 G/L* 4.9 – 10.5 G/L*
Leukocytes (WBC)***4.0 – 9.0 G/L* 4.0 – 9.0 G/L*


  • G/L – Giga/L = 10 9 /L
  • T/L – Tera/L = 10 12 /L
  • fl – femtoliter
  • pg – pictograms

: per. from English. / ed. WELL. Titsa. – M.: Medicine, 1986, 480 p.

*** The values ​​were developed by a working group of experts at the VNMKTs on laboratory business and approved by the USSR Ministry of Health in 1978 y. 011 Cord blood 135 – 205 135 – 205 2 weeks 134 – 198 134 – 198 1 month 107 – 171 107 – 171 2 months 94 – 130 94 – 130 4 months 103 – 141 103 – 141 6 months 111 – 141 111 – 141 9 months 114 – 140 114 – 140 1 – 2 years 113 – 141 0021

2 – 5 years 110 – 140 110 – 140 5 – 9 years 115 – 145 115 – 145 9 – 12 years 120 – 150 120 – 150 12 – 14 years 115 – 150 12 0 – 160 15 – 17 years old 117 – 153 117 – 166 18 – 44 years old 117 – 155 132 – 173 45 – 64 years old 117 – 160 131 – 172 65 – 74 117 – 161 126 – 174

Venous or capillary blood with EDTA salts is taken for research. When performing studies on hematological analyzers, the photometric method is used.

Errors in hemoglobin measurement

High concentration results may be due to the following factors:

  • Hyperlipidemia.
  • Hyperbilirubinemia.
  • Cryoglobulinemia.
  • High leukocytosis.
  • Excess of unstable hemoglobins.

Clinical and diagnostic value:

  • Increased concentration is caused by dehydration, as well as primary or secondary erythremia.
  • Decreased concentration occurs with anemia or overhydration.

Some patients whose blood hemoglobin is higher than 75 g/l can increase the hemoglobin level by 20-30 g/l by taking iron supplements for 10 days, but the iron deficiency itself is not compensated. If the patient (body weight 70 kg) also receives a blood transfusion (500 ml), an increase in hemoglobin level by 12 g/l is possible.


Normal values ​​

9 0021

Age Women (t/l) Men (t/l)
Cord blood 3. 9 – 5, 5 3.9 – 5.5
2 weeks 3.9 – 5.9 3.9 – 5.9
1 month 3.3 – 5.3 3.3 – 5.3
4 months 3.5 – 5.1 3.5 – 5.1
6 months 3.9 – 5.5 3.9 – 5.5
9 months 4.0 – 5.3 4.0 – 5.3
1 – 2 years 3.8 – 4.8 3.8 – 4.8
3 – 8 years 3.7 – 4.9 3.7 – 4.9
9 – 12 years 3.9 – 5.1 3.9 – 5.1 900 12
12 – 14 years old 3.8 – 5.0 4.1 – 5.2
15 – 17 years old 3.9 – 5.1 4.2 – 5.6
18 – 44 years old 9 0012

3.8 – 5, 1 4.3 – 5.7
45 – 64 years 3.8 – 5.3 4.2 – 5.6
65 – 74 years old 3. 8 – 5.2 3.8 – 5.8

Venous or capillary blood with EDTA salts is used for research.

Clinical and diagnostic value

The number of red blood cells increases with:

  • Dehydration.
  • Reactive erythrocytosis, which is caused by a lack of oxygen in the tissues due to congenital or acquired heart defects, with cor pulmonale, frequent stay at high altitudes, with emphysema.
  • Reactive erythrocytosis caused by Cushing’s disease or syndrome, corticosteroids, renal pelvic edema, various neoplasms, erythremia, polycystic kidney disease.

The number of erythrocytes decreases with:

  • Anemia;
  • Hyperhydration.
  • Major blood loss.
  • Late pregnancy.


9002 1

9000 9 12 – 14 years old

9 0009 39 – 50%

Age Women Men
Umbilical cord blood 42 – 60% 42 – 60%
2 wk. 41 – 65%41 – 65%
1 month 33 – 55% 33 – 55%
2 months 28 – 42% 28 – 42%
4 months 32 – 44% 32 – 44%
6 months 31 – 41% 31 – 41%
9 months 32 – 40% 32 – 40%
1 year 33 – 41% 33 – 41%
1 – 2 years 32 – 40% 32 – 40%
3 – 5 years 32 – 42% 32 – 42%
6 – 8 years 33 – 41% 33 – 41%
9 – 11 years 34 – 43% 34 – 43%
34 – 44% 35 – 45%
15 – 17 years old 34 – 44% 37 – 48%
18 – 44 35 – 45% 39 – 49%
45 – 64 35 – 47%
65 – 74 35 – 47% 37 – 51%

Venous blood with EDTA salts and capillary blood collected in a hematocrit capillary are used for research. In modern analyzers, hematocrit (Hct) is a secondary calculated parameter.

False hematocrit possible at:

  • Development of cryoglobulinemia.
  • The presence of huge platelets in the sample.
  • Increased white blood cell count (more than 50 g/l).
  • Hyperglycemia (greater than 33.3 mmol/l).

False-low in hardware analysis causes:

  • RBC agglutination.
  • Microerythrocytosis (less than 36 vials).

Clinical and diagnostic value:

An increase in hematocrit is observed when being at high altitude, the presence of neoplasms in the kidneys or their polycystic, chronic lung diseases, erythrocytosis, or conditions leading to a decrease in the volume of plasma circulating in the body – diabetes, non-stop vomiting, increased sweating).

The hematocrit value decreases with anemia or due to an increase in the volume of circulating plasma during pregnancy, overhydration.

Mean erythrocyte hemoglobin (MHC)

9000 8

Age Women (pg) Men (pg)
Cord blood 31 – 37 31 – 37
2 weeks 30 – 3730 – 37
1 month 29 – 36 29 – 36
2 months 27 – 34 27 – 34
4 months 25 – 32 25 – 32
6 months 24 – 30 24 – 30
9 months 25 – 30 25 – 30
1 year 24 – 30 24 – 30
1 – 2 years 22 – 30 22 – 30
3 – 8 years 25 – 31 25 – 31
9 – 14 years 26 – 32 26 – 32
15 – 17 26 – 34 27 – 32
18 – 44 27 – 34 27 – 34
45 – 64 27 – 34 27 – 35
65 – 74 27 – 35 27 – 34

Venous or capillary blood with EDTA salts is used for research.

MHC is used to determine the average hemoglobin content in a single erythrocyte. To calculate the parameter, the following formula is used:

MHC pg \u003d Hb g / l / RBC T / l

The numerator is the total indicator of hemoglobin.

The denominator is the total number of erythrocytes.

The parameter is defined in picograms. To determine the average amount of hemoglobin in erythrocytes, a parameter such as a color index – CPU is also used. It is defined in arbitrary units.

CP = Hb g % * 3 / first 2 digits of RBC count

Or calculated as follows:

CP = MCH pg / 33.4

CP can completely replace MCH. If an automatic hematology analyzer is used for studies that calculates the MCH value, then there is no need to additionally determine the CPU.

Hyperchromia or an increase in MCH greater than 34 pg is not due to an increase in the concentration of hemoglobin in erythrocytes, but is caused by an increase in their volume. A false overestimation of this indicator is possible with errors due to an increased level of hemoglobin and a reduced number of red blood cells. A decrease in MCH to a value of 27 pg or less is called hypochromia.

Clinical and diagnostic value:

  • An increase is possible with anemia due to liver cirrhosis, hyperchromic or megaloblastic anemia.
  • Decrease causes anemia in malignant neoplasms, hypochromic anemia.

Mean erythrocyte hemoglobin concentration MCHC

Age Women/Men (g/dl)
Cord blood 30 – 36
2 weeks 28 – 35
1 month 28 – 36
2 months 28 – 35
4 months 29 -37
6 – 12 months 32 – 37
1 – 2 years 32 – 38
3 – 74 years 32 – 37 900 12

The study is carried out using venous or capillary blood with EDTA salts. The indicator characterizes the amount of hemoglobin in the average erythrocyte and is calculated in% according to the following formula:

MCHC = Hb g/l * 10 / Ht %

This is one of the most stable and genetically determined parameters that is not affected by age, gender or race. The concentration of hemoglobin depends on the structure of the cell and does not change throughout life, so the limits of the norm are quite narrow and practically not subject to fluctuations in various pathologies.

There is a clearly defined upper limit for the MCHC. This parameter may be incorrectly determined by inaccurate counting of the number of red blood cells. With it, it is convenient to control the accuracy of the device.

Clinical and diagnostic value:

  • An increased value occurs with hypertensive disorders in the water-electrolyte system or hyperchromic anemia.
  • A decrease in the values ​​of the indicator is typical for hypotonic disorders of the water and electrolyte balance or hypochromic anemia.

Important! Since the maximum value of hemoglobin solubility in water is 37 g / dl, an excess of an MCHC value of more than 37 indicates the need for a second study. An increased value can also cause hemolysis.

Accurately determine the violations in the water-electrolyte balance using not the absolute values ​​of MCHC, but their dynamics.


Age Women (fl) Men (fl) 9 0012
Cord blood 98 – 118 98 – 118
2 weeks 80 – 140 80 – 140
1 month 91 – 112 91 – 112
2 months 84 – 106 84 – 106
4 months 76 – 97 76 – 97
6 months 68 – 85 68 – 85
9 months 70 – 85 70 – 85
1 year 71 – 84 71 – 84
2 – 5 years 73 – 8573 – 85
5 – 9 years 75 – 87 75 – 87
9 – 12 years 76 – 90 76 – 90
12 – 14 years 73 – 95 77 – 94
15 – 17 years 80 – 96 79 – 95
18 – 44 81 – 100 80 – 99
45 – 64 81 – 101 81 – 101
65 – 74 years 81 – 102 81 – 103

Almost all modern hematology analyzers can measure this indicator. Data are given in units of femtoliters – fm.

You can also use the formula to calculate:

MCV fl = Hct % * 10 / RBC T/l

The average red blood cell volume changes throughout life. It allows you to quantify microcytosis or macrocytosis. The value of this indicator can be effectively used in the differential diagnosis of anemia.

It is the average volume rather than the diameter of erythrocytes that is more objective in clinical studies. This is due to the fact that the diameter can vary significantly under the influence of normal physiological factors – time of day, physical activity. In automatic analysis, blood is diluted in an isotonic solution, which has constant physico-chemical parameters, ensuring stability when measuring MCV.

MCV rate is 80 to 100 fl. Volume distribution curves are shown in the graph.

The body itself regulates the number of red blood cells and the level of hemoglobin, ensuring their relative constant ratio. The relationship between the number of red blood cells and their average volume is shown on the graph:

Clinical and diagnostic value:

  • Less than 80 fl. Microcytic anemia, or accompanied by microcytosis.
  • 80 to 100 vials Normocytic anemia, or accompanied by normocytosis.
  • Over 10 vials Macrocytic and megablast anemia, as well as those accompanied by macrocytosis.

RBC anisocytosis RDW

Values ​​between 11.6-14.8% are considered normal.

This parameter characterizes the distribution width of erythrocytes. The function of determining this value is incorporated in most modern models of hematological analyzers. Calculated by the formula:

RDW % = SD / MCV fl * 100%

SD is the standard deviation of red blood cell volume from the mean value.

In a healthy person, the normal value may be 12-14%. There are no conditions that can cause this parameter to decrease. Due to differences in blood processing algorithms, even in different devices, different values ​​​​of this indicator can be obtained. Clinical and diagnostic value:

  • MCV > 80 fl, RDW normal. Anemia due to chronic disease, thalassemia.
  • MSV > 80 fl, RDW high. Sideroblastic and iron deficiency anemia.
  • Increased RDW. Perhaps in conditions such as macrocytic anemia, bone marrow metaplasia, bone marrow metastases.

Hematology analyzers detect anisocytosis much better. Evaluation of its degree under a microscope is possible with a large error. This is due to the fact that when a blood smear dries, the diameter of red blood cells decreases by 10-20%. Automated counting uses a conductometric method to ensure cell stability, resulting in faster and more accurate results.

Attention! Medica Group sells automated microbiology analyzers and culture media vials, but does not provide with the collection or interpretation of blood test results.

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Complete blood count | decoding, indicators and norms of the UAC

Complete or clinical blood test is a detailed study prescribed by a doctor when a patient contacts and complains of feeling unwell.

Contains information about the nature of hematopoiesis, reflecting the general state of the body, the values ​​of quantitative and qualitative changes in the composition of the blood.

Biochemical results usually make it possible to determine the diagnosis immediately or after additional examinations: ultrasound, X-ray.

Blood transports various substances between tissues, organs and systems, ensuring the unity of the body. Thus, the processes occurring in different tissues and organs are reflected in the state of the blood.

Blood consists of a liquid part – plasma and formed elements – leukocytes, platelets, erythrocytes, each type of which has functions, for example, leukocytes are responsible for protecting immunity, platelets – for clotting, erythrocytes provide the body with oxygen and carbon dioxide.

Analysis can identify possible diseases, in which case the composition of the blood changes. Clinical analysis sometimes allows you to identify the disease at an early stage, when the symptoms of the disease do not even appear. Clinical analysis helps clients understand the course of the disease, determine the intensity of the pathological process, so it is used as a diagnosis of inflammation, allergies, and diseases. A repeated general analysis (CLA) is carried out as prescribed by a doctor in order to evaluate the effectiveness of treatment and, if necessary, adjust it. Hematological diseases require a primary study of cells for preventive purposes.

Deciphering the abbreviation of the general blood test

Now the English abbreviation is used on the forms with the results of the KLA, which means:

  • WBC – white blood cells – white blood cells – Leukocytes;
  • RBC – red blood cells – red blood cells – Erythrocytes;
  • HGB – hemoglobin – Hemoglobin;
  • HTC – hematocrit – Hematocrit;
  • MCV – mean corpuscular volume – The average volume of erythrocytes;
  • MCH – mean concentration hemoglobin – The average content of hemoglobin in an erythrocyte;
  • MCHC – mean corpuscular hemoglobin concentration – The average concentration of hemoglobin in an erythrocyte;
  • RDW – red cell distribution – Red blood cell distribution index;
  • PLT – platelets – platelets;
  • MPV – mean platelets volume
  • PTC – Thrombocrit – Thrombocrit.

Indicators of the general blood test

Complete blood count contains mandatory parameters. A pediatrician, therapist or other specialists may refer the patient to an extended clinical blood test, which additionally includes the necessary indicators.


Hemoglobin is a protein that is part of the erythrocyte. It delivers oxygen from the lungs, and carbon dioxide, on the contrary, to the lungs. It contains iron, which makes red blood cells red.

Level is a very important indicator of him. Due to a decrease in its amount, the body receives less oxygen, which is necessary for its life.

For men, it is considered normal – from 130-160 g/l, for women – 120-140 g/l. The saturation of this element in newborn children significantly exceeds the norm in adults. However, in the first weeks it gradually decreases.

When the hemoglobin value is below normal, then anemia is diagnosed, a low level can also indicate hyperhydration of the body due to increased fluid intake. Elevated hemoglobin can be observed with thickening of the blood due to a violation of the function of coagulation or the use of diuretic drugs. Dehydration of the body can be caused not only by pathology, but also by increased physical exertion or extreme heat. An elevated hemoglobin level is a typical sign of erythremia – impaired blood formation, an increased number of red blood cells. Hemoglobin can also increase due to diseases of the respiratory system against the background of a constant lack of oxygen.

red blood cells

Erythrocytes are red blood cells responsible for metabolic processes. The blood is red in color, due to the high content of red blood cells, compared to other formed elements. Red blood cells contain hemoglobin, so they are involved in the process of oxygen metabolism in the body.

Norms for men – 4-5 * 1012 per liter of blood, for women – 3.9-4.7 * 1012, which depend on the laboratory.

With anemia, bleeding, pregnancy, hyperhydration, the content of erythrocytes in the blood decreases. Excess, as a rule, indicates erythremia, such tumor formations as a kidney cyst or dropsy of the renal pelvis, dehydration and fluid loss with sweat, vomiting, diarrhea, when the blood thickens.

The average volume of erythrocytes MCV – mean corpuscular volume – the norm for men is 80-95 and for women – 80-100.

The mean concentration of hemoglobin in an erythrocyte MCH – mean concentration hemoglobin – this indicator increases with hypothyroidism, anemia of an autoimmune nature, B12-deficiency anemia, liver pathologies, alcohol dependence, and decreases due to iron deficiency anemia or decreased thyroid function.

The average concentration of hemoglobin in erythrocytes MCHC – mean corpuscular hemoglobin concentration – an increase in this indicator almost always indicates a hardware error, and its decrease indicates iron deficiency anemia.


Hematocrit – the ratio of formed elements to the total volume of blood in percent.

An increase in hematocrit occurs as a result of:

  • dehydration;
  • peritonitis;
  • extensive burns;
  • polycythemia.

A decrease in hematocrit is observed against the background of:

  • anemia and iron deficiency;
  • heart disease;
  • vascular and kidney pathologies;
  • chronic hyperazotemia – increased nitrogen levels in the blood

color index

The color index of blood is calculated according to a formula in which the hemoglobin level and the number of erythrocytes are correlated. Normally, the color index is close to one (0.85-1.05). Anemia leads to a deviation of the indicator. If the color index is below normal, then this indicates iron deficiency anemia, when hemoglobin is reduced more than the number of red blood cells. Anemia of another type is characterized by a color index above the norm, in this case, the number of red blood cells is reduced more than hemoglobin.


Reticulocytes are young, immature erythrocytes, which are always present in the blood, since the process of formation of erythrocytes in the blood is continuous. Norm: 0.2-1% or 2-10 reticulocytes out of 1000 erythrocytes. If reticulocytes are more than normal, then the body feels the need to increase red blood cells, for example, due to large blood loss. In the presence of anemia, radiation sickness, oncology (if metastases have affected the bone marrow), some kidney diseases are characterized by a reduced level of reticulocytes. Determining the RET indication is required for bone marrow transplantation, chemotherapy, as well as for assessing the processes of hematopoiesis, therapy with drugs containing iron, folic acid, vitamin B12, erythropoietin.


Platelets are responsible for blood clotting. They provide not only hemostasis, but also the body’s immunity during infection. Normal platelet content: 180-320*109 per liter. A decrease in this level may indicate the presence of an inflammatory process in the body, an autoimmune disease, leukemia; AIDS, alcohol poisoning, drugs, chemicals, aplastic anemia, bone marrow diseases.

An increase in the level occurs after blood loss and previous operations, and is also observed in malignant neoplasms, spleen atrophy, colitis, tuberculosis, osteomyelitis, joint diseases, liver cirrhosis, myelofibrosis.


Leukocytes are white blood cells that perform a protective function. The norm of their content is in the range of 4-9*109 per litre.

A high level of leukocytes is observed in infectious diseases caused by bacteria, inflammatory processes, allergic reactions. Their number increases as a result of recent stress, bleeding, as well as due to tumor processes and some other pathologies.

The depressed state of the immune system causes a decrease in leukocytes due to weight loss, severe toxicosis, sepsis, diseases of the hematopoietic organs, radiation sickness, autoimmune diseases, immunodeficiency, leukemia, viral infections such as influenza, measles, rubella, as well as due to the use of sulfonamides, non-steroidal anti-inflammatory drugs.

Not only the total number of leukocytes is important, but also their five types – neutrophils, eosinophils, basophils, lymphocytes and monocytes, which have different functions, so it is important to know their ratio in the blood, that is, the leukocyte formula.

Pathological leukocytosis is observed in:

  • purulent inflammatory diseases;
  • severe burns;
  • the use of the hormone insulin;
  • malignant tumors;
  • epilepsy;
  • severe poisoning;
  • allergies.


Neutrophils are non-specific immune response cells that have bactericidal and detoxifying functions. In the inflammatory process, there is an increase in the number of mature neutrophils that are produced by the bone marrow. First, a myelocyte is formed, which then becomes a metamyelocyte, then the stage of a stab neutrophil begins. A mature neutrophil is segmented. In the normal state of the body, myelocytes and metamyelocytes in the blood should be absent. Segmented neutrophils should make up 47-72% of the total number of leukocytes, and stab – 1-6%. When immunity is weakened, the proportion of stab nuclei increases, in this case the body sends still immature neutrophils to fight the infection. An analysis with such a result is called a stab shift.

Stress, intoxication, inflammation, bacterial infection, cancer also increase the number of neutrophils in the blood.


Eosinophils neutralize immune complexes caused by foreign allergens. The norm of eosinophils is 1-5% of the total. An increase in this indicator indicates an allergic reaction or a parasitic infection (primarily an infection with worms).


Normal blood levels are: 0-1% of the total.


Lymphocytes are the main cells of the immune system that recognize and destroy the invading agent. This is how the body fights viruses. The normal level of lymphocytes is 19-37% of the total. This figure is higher in children than in adults. At the age of one month to two years, the main type of leukocytes is lymphocytes. By the age of five, the number of leukocytes is already comparable to the number of neutrophils. Children at the age of 15 still have more lymphocytes than adults.

With a viral infection, with toxoplasmosis, tuberculosis, syphilis, there is an increased content of lymphocytes in the blood. A reduced number of lymphocytes indicates HIV infection and a depressed state of the immune system.


Monocytes stay in the blood for about 30 hours. Then they move from the bloodstream to tissues, where they turn into macrophages in order to finally destroy bacteria and tissues that have died from inflammation. The norm of monocytes is 3-11% of the total. An increased number of monocytes is a specific sign of mononucleosis, and is also characteristic of tuberculosis, sarcoidosis, syphilis, rheumatoid arthritis, indolent and long-term diseases.

ESR – erythrocyte sedimentation rate

Compared to plasma, red blood cells are a heavier fraction of the blood. Therefore, when the test tube is vertical, its contents are divided into two parts: in the lower part – thick and dark erythrocytes, and in the upper part – light plasma. The erythrocyte sedimentation rate is measured in mm/hour. Norm: for men – 2-10 mm / hour, for women – 2-15 mm / hour. In children, pregnant women and the elderly, normal values ​​​​are different.

The erythrocyte sedimentation rate increases with an increase in their mass, that is, strong gluing occurs between them. The most common cause of such bonding is an inflammatory process. As a rule, the stronger the inflammation, the higher the ESR.

With an increase in ESR, autoimmune diseases occur in the body, blood, liver and biliary tract, and the following diseases can also occur:

  • heart attack;
  • stroke;
  • tuberculosis;
  • malignant tumors;
  • thyrotoxicosis;
  • diabetes mellitus.

Preparing for a complete blood count

  1. Two weeks before the test, it is important to stop taking medicines for laboratory testing. If the medications taken are vital, then the doctor adjusts the treatment, because some drugs can affect blood parameters.
  2. The day before the study, you should exclude the use of alcohol, fatty, spicy and fried foods, avoid physical and emotional stress, you should also not take a KLA after an X-ray examination, physiotherapy, sunbathing.
  3. Dinner on the eve of the study no later than 22.00.
  4. It is advisable to donate blood for general analysis in the morning on an empty stomach. Biological material for both capillary and venous blood can serve. Before this, you can not smoke, drink coffee, tea. Drinking water is allowed in a volume of not more than 0.5 liters. If the analysis is taken during the day, then after the last meal, approximately 5 hours should pass.
  5. Women, undergoing a routine examination, it is advisable to wait with the delivery of the KLA until the end of menstruation.

The procedure for taking the KLA

  1. Blood sampling for general analysis in both a child and an adult is almost the same.