Understanding the Complete Blood Count (CBC)

The CBC – providing information about your health

The human body is primarily made up of water and cells. Many of the cells group together to form the skin, muscles, bones and organs, such as the heart, lungs, kidneys, etc. Such cells are stationary, staying in one place within the body. Some very special and important cells, however, move throughout the body by traveling (circulating) in the blood. These circulating cells provide oxygen to all of the stationary cells in the body, help fight infection throughout the body, and help stop bleeding after an injury. Information about these cells can provide important clues about the overall health of the body.

The complete blood count, or CBC, is a lab test that provides information about these circulating cells. First, a sample of your blood is collected and sent to the lab. A lab instrument then automatically counts the number of each type of circulating cell. If results from the automated instrument are outside specified limits, a medical technologist will examine the cells closely so complete information about the cells can be provided.

Results from the CBC test can help:

• Provide basic information about your health
• Detect a health condition before you have any symptoms
• Confirm that a health condition exists
• Identify the causes of your symptoms
• Find out if your medicine is working
• Rule out a disease
• Establish a baseline that can be used for comparison with future test results

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Reporting and interpreting the results

Your CBC test results are usually reported along with a reference range of expected or desired values to help guide your doctor in interpreting them. Reference ranges reflect the numeric values found in healthy people; however, a small number of healthy people (5%) have values that are higher or lower than the ones shown in the reference range. Thus, values higher or lower than those in the reference range might or might not indicate a medical condition.

In addition to the reference range, your doctor will consider other factors when interpreting your CBC test results. These factors include your personal and family medical history, results from a physical exam, and other test results. Your doctor will also consider factors that might cause an incorrect test result such as improper sample collection or handling. Therefore, it’s important that you talk with your doctor about the meaning of your test results.

This brochure includes a brief description of the items included in the CBC test report. The descriptions can help you understand your results so you can have a more meaningful discussion with your doctor. Additionally, items in the CBC are summarized in the table at the end of this brochure for quick reference.

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Red Blood Cells (RBCs) – transporting oxygen throughout the body

RBCs play a vital role in transporting oxygen from the lungs to the rest of the body. These oval-shaped cells contain hemoglobin, the protein that binds oxygen while it is being carried to all the stationary cells in the body (cells in the skin, muscle, bone and organs). The chemical process that converts the nutrients found in food into energy requires oxygen. All the stationary cells require energy to function; thus, they need oxygen and are dependent on the RBCs to transport it.

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More about hemoglobin

Hemoglobin (Hb or Hgb) is an iron-rich protein that carries oxygen and makes the blood red. Since hemoglobin is contained only in the RBCs, a low number of RBCs leads to low levels of hemoglobin. However, if there is something wrong with the RBCs, hemoglobin levels can be low even when the RBC count (i.e. number of RBCs) is within the reference range. So a CBC test report includes the number of RBCs, the amount of hemoglobin, and other measurements related to the RBCs.

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Other RBC measurements

The hematocrit reflects the amount of space in the blood that is occupied by RBCs. Hematocrit measurements are affected by the number of RBCs and by the size of the RBCs.

The mean corpuscle (cell) volume (MCV) is a measurement of the average size of the RBCs. Small-sized RBCs result in a lower MCV, while larger RBCs result in a higher MCV.

The mean corpuscular hemoglobin (MCH) reflects the average amount of hemoglobin in a person’s RBCs. RBCs with more hemoglobin result in a higher MCH and vice versa.

The mean corpuscular hemoglobin concentration (MCHC) is a measurement of the average amount of hemoglobin in the RBCs compared to the average size of the RBCs. Put another way, the MCHC is the ratio of the MCH to the MCV.

The red cell distribution width (RDW) reflects the degree of variation in size of the RBCs. Not all the RBCs are the same size; some are larger and some are smaller. The RDW measurement is affected by the size of the smallest RBC and the size of the largest RBC.

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What this means to me and my doctor

In patients with anemia, hemoglobin levels are low and the patient may be frequently tired and have little energy. This is because there is not enough hemoglobin to carry oxygen to the stationary tissues; thus, there is not enough oxygen available to convert nutrients into energy. The RBC count, hematocrit level, MCV, MCH and MCHC might also be low in patients with anemia.

Low RBC counts, hemoglobin and hematocrit levels can be caused by other things too, such as a lot of bleeding or malnutrition (not enough nutrients in the food eaten). Kidney disease, liver disease (cirrhosis), cancer, and medications used to treat cancer can also cause low levels.

An increased RBC count and increased levels of hemoglobin and hematocrit may be caused by dehydration (not enough water in the body) or by some diseases (see table).

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White Blood Cells (WBCs) – defending your body

WBCs help the body fight illness or infection. As part of the immune system, they recognize and fight things that are foreign to (not part of) the body. The number of WBCs (WBC count) is lower than the number of RBCs; however, the WBCs are larger in size RBCs. There are 5 types of WBCs; each type plays a different role in protecting the body from invaders.

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What this means to me and my doctor

The WBC count may increase when you have an infection caused by bacteria, viruses, fungi, or parasites. The WBC count can also increase in patients with leukemia, a cancer of the blood. Thus, doctors use the WBC count to help determine if a patient has an infection or leukemia. When the WBC count is increased, the type of WBC can help differentiate between a bacterial infection, viral infection or leukemia. Doctors also use the WBC count to monitor various types of illness, since it may decrease in response to therapy during recovery from an illness. A low WBC count can mean you are at risk of getting an infection since you have fewer WBCs to fight infection.

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Types of WBCs

• Neutrophils are cells that protect the body from bacterial infections. They move toward bacteria and then swallow them up so the bacteria cannot harm the body.
• Lymphocytes are cells that protect the body against viruses, bacteria, and fungi. One type of lymphocyte (B-cell) produces antibodies that attack and destroy the bacteria and viruses. Another type of lymphocyte (T-cell) can directly attack viruses and bacteria and can stimulate the B-cells to produce antibodies.
• Monocytes are cells that consume dead or damaged cells. They are the “clean-up crew”.
• Eosinophils are cells that kill parasites and contribute to allergic reactions.
• Basophils are cells that release histamines during allergic reactions.

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The differential – visualizing the cells

When performing a differential, a medical technologist looks at the various cells under a microscope. A differential provides information about the relative numbers (that is, the percentage) of each type of WBC. Such information helps the doctor determine whether an illness is caused by a bacteria, a virus, or leukemia. A differential can be used to monitor patients with allergies and to determine how a patient is recovering from an illness or responding to therapy.

In addition to the cell types listed previously, certain cell types that don’t normally appear in the blood can be reported in the differential. These cells include promyelocytes, metamyelocytes, blasts, etc. Presence of any of these cells indicates a need for follow-up with your doctor.

Finally, the differential can provide information about the appearance of RBCs, since the cells are visualized under a microscope. The appearance of RBCs helps differentiate the various types of anemia.

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Platelets – helping to clot blood

Platelets are the smallest blood cells. They are an important part of blood clotting. These small cells clump together and form a sticky mass that helps the blood to clot. Blood clots help your body handle injury by stopping or preventing bleeding. Blood clots can also cause problems, however, when they occur within the blood vessels or the heart; such clots cause a blockage known as thrombosis.

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Platelet Counts – assessing your body’s ability to clot blood

A CBC includes the number of platelets and the mean platelet volume (MPV). MPV is a measurement of the average size of the platelets. A higher MPV roughly indicates better platelet function. Some medical conditions are associated with a high MPV and some are associated with a low MPV. Thus, the MPV can sometimes be helpful in telling apart different disorders.

A decreased number of platelets (thrombocytopenia) is associated with bleeding. Some causes include certain rare inherited disorders, leukemia, autoimmune disorders (e.g., rheumatoid arthritis or lupus) and medications. A falsely low platelet count, which is not associated with bleeding, can be caused by a rare error in blood sample collection: instead of staying in a liquid form, the sample clots (becomes solid), thus using up the platelets.

An increased platelet count is less common and is associated with clotting disorders such as thrombocythemia. Platelet counts can also be increased in some cancers and following infections or other medical conditions.

Aspirin can decrease the platelet function, so it’s important to consult with your doctor when taking large amounts of aspirin or when taking aspirin for an extended period of time. Many over-the-counter medications contain aspirin, which may be listed as acetylsalicylic acid, salicylate, or 2-(acetyloxy) benzoic acid.

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Table: Items included in a CBC Test Report

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Polycythemia – StatPearls – NCBI Bookshelf

Continuing Education Activity

Polycythemia, also called erythrocytosis, refers to increased red blood cell mass, noted on laboratory evaluation as increased hemoglobin and hematocrit levels. Polycythemia vera is a subtype of polycythemia and can be associated with the overproduction of more than just the erythrocytic lineage. The clinical significance of erythrocytosis, due to any cause, is related to the associated risk of thrombotic events due to hyperviscosity of blood. Additionally, in cases of polycythemia vera, there is potential for progression to leukemia. This activity reviews the evaluation, treatment, and potential complications of polycythemia vera and highlights the role of the interprofessional team in identifying and treating this condition.

Objectives:

• Describe the typical presenting features of polycythemia.

• Outline the management of polycythemia.

• Review the potential complications of polycythemia.

• Use interprofessional team strategies to improve care coordination and communication to improve the evaluation and management of patients with polycythemia and optimize outcomes.

Access free multiple choice questions on this topic.

Introduction

Polycythemia, or erythrocytosis, refers to an increase in the absolute red blood cell (RBC) mass in the body. In practice, this is reflected by an increase in hemoglobin levels, or hematocrit, over what is considered physiologic for the particular age and gender.

The standard RBC mass does not usually exceed 36 ml/kg in males and 32 ml/kg in females. The reference ranges for normal hemoglobin levels and hematocrit vary depending on altitude, ethnicity, and country.[1] However, as a frame of reference, the hemoglobin and hematocrit of a healthy adult male are 16 g/dL +/- 2 gm/dl and 47% +/- 6%, respectively. The hemoglobin and hematocrit of a menstruating adult female are usually 13 g/dL +/- 2 gm/dl and 40% +/- 6%, respectively. Polycythemia in newborns is defined as a central venous hematocrit over 65% or a hemoglobin value above 22 g/dL.[2]

Polycythemia vera is a sub-type of polycythemia. Often referred to colloquially as simply “polycythemia,” it is an acquired, Philadelphia-chromosome negative[3], myeloproliferative disorder. This condition can be associated with the overproduction of all three cell lines but with a notable predilection towards red blood cells.

The clinical significance of erythrocytosis, due to any cause, lies in the associated risk of thrombotic events due to hyperviscosity of blood. Additionally, the potential for progression to leukemia in cases of polycythemia vera also warrants additional management strategies to be implemented.

Etiology

Classification

Spurious Polycythemia

This occurs due to volume contraction rather than an increase in true RBC mass.

Causes include

• Severe dehydration due to isolated fluid loss: potentially seen in diarrhea and severe vomiting

• Gaisbock syndrome: Usually seen amongst obese, hypertensive males. Smoking, excessive alcohol, and use of diuretics are contributory.[4]

True Polycythemia

Further stratified based on serum erythropoietin (EPO) levels as follows:

Low serum EPO levels (Primary polycythemia)

High serum EPO levels (Secondary polycythemia)

• High altitude

• Respiratory disorders: Chronic obstructive pulmonary disease (COPD), Pickwickian syndrome, uncontrolled asthma

• Cyanotic heart diseases with right-to-left shunts

• Renal disorders: Renal cysts, kidney cancer, renal artery stenosis, Bartter syndrome, focal sclerosing glomerulonephritis

• Elevated carboxyhemoglobin: Usually seen in smokers, people working on cars in closed spaces, or people working in boiler rooms

• Hemoglobinopathies: High-affinity hemoglobins such as Hb Yakima, methemoglobinemia

• EPO-secreting tumors: sources include hepatomas, uterine leiomyomas, and cerebellar hemangiomas

• Iatrogenic causes: Including erythropoietin analog administration, anabolic steroids, and testosterone replacement therapy

Neonatal Polycythemia

• The increase in hematocrit is a normal compensatory mechanism in infants due to the relative tissue-level hypoxia in the intrauterine environment. It is exacerbated by the high affinity of fetal hemoglobin for oxygen.

Epidemiology

The prevalence of polycythemia vera has been estimated to be approximately 22 cases per 100,000 population[5]. It is believed to occur more frequently among Jewish patients of Eastern European descent than other Europeans and Asians. Polycythemia vera shows a male preponderance in all races and ethnicities, with a male-to-female ratio of approximately 2 to 1. The median age of presentation of PV is 60 years, with patients seldom seen before the age of 40. Polycythemia due to hemoglobinopathies and congenital cyanotic heart diseases is likely to be detected in significantly younger patients.

Pathophysiology

The pathophysiology would vary, depending on the cause in consideration.

High EPO Levels

Cellular hypoxia can occur due to any cause that triggers the release of erythropoietin from the renal peritubular lining capillary cells. A small amount of EPO is produced by the liver as well. EPO, in turn, acts on erythroid progenitor cells and stimulates erythropoiesis. 

Low EPO Levels

The primary defect in nearly 95% of cases of polycythemia vera is an acquired mutation in exon 14 of the tyrosine kinase JAK2 (V617F). Mutations have also been described in exon 12 of JAK2. These mutations result in a loss of the auto-inhibitory pseudo-kinase domain of JAK2, resulting in its constitutive activation. This constitutive activation results in both hypersensitivity to EPO and EPO-independent erythroid colony formation.[6]

Histopathology

Bone marrow examination is not routinely employed. Its utility largely remains restricted to cases where the clinical suspicion of polycythemia vera is high, despite the absence of a JAK2 (V617F) mutation, or if facilities to test for the mutation are unavailable. Classical findings, when coexistent with other suggestive hematologic parameters, help support a diagnosis of polycythemia vera. [7]

Strongly suggestive findings include a hypercellular marrow with erythroid hyperplasia and subtle megakaryocytic atypia.[8] Tri-lineage hyperproliferation is also an expected feature.

History and Physical

History

• Common presenting symptoms, usually non-specific, include fatigue, headache, dizziness, transient blurry vision, amaurosis fugax, and other symptoms suggestive of transient ischemic attacks (TIAs).

• Infrequently, patients may complain of pruritus after a warm water shower, particularly over the back.

• A history of epistaxis, gastrointestinal (GI) bleeding, or easy bruising may be forthcoming.

• Peptic ulcer disease commonly coexists, and patients may present with non-specific abdominal pain. Left hypochondrial pain and early satiety should raise the suspicion of splenomegaly.

• Rarely, patients may present with a history of unexplained thrombotic complications, such as Budd-Chiari syndrome or digital infarcts.

• It is vital to try and elicit etiology-specific history, such as a history of smoking, an extended stay at high altitudes, and congenital cardiac disease, among others. Significant family history may be noted in patients with hemoglobinopathies.

Physical Examination

• Abnormal facial ruddiness may be prominent.

• Cyanosis and clubbing, along with the presence of a murmur on auscultation, provide strong evidence favoring a congenital cyanotic heart disease.

• Nicotine staining of the nails and teeth provides presumptive evidence of smoking, even in a non-forthcoming patient.

• Morbid obesity could raise the possibility of Pickwickian syndrome, whereas a barrel chest could suggest obstructive lung disease.

• Examining the abdomen may lead to finding a palpable spleen or eliciting the bruit of renal arterial stenosis in a thin-built individual.

Evaluation

An evaluation must proceed sequentially. Due to the broad array of potential causes, it is vital to consider the appropriate investigation in that specific clinical context. However, the following may provide a frame of reference:

Hemogram

Based on the WHO 2017 criteria, hematocrit levels above 49% in males and 48% in females at sea level are to be considered suggestive of polycythemia vera. In cases of polycythemia vera, there could be a concurrent increase in platelet and leukocyte counts as well. The leucocyte count is usually between 10,000 to 20,000/microliter and may show eosinophilia and basophilia. Platelet counts may rarely exceed 1,000,000/microliter.

Radioisotope Studies

Radioisotope studies using chromium-labeled autologous RBC transfusions accurately determine the true RBC mass and conclusively exclude spurious polycythemia.

Serum EPO Levels

The presence of either high or low EPO levels directs the further plan of evaluation.

• Low EPO Levels

Low EPO levels indicate primary polycythemia. Subsequent evaluation should be targeted toward the detection of polycythemia vera.

JAK2 mutation studies are virtually diagnostic for polycythemia vera (95% cases). Mutations may occur either in exon 14 (more commonly) or in exon 12.

• High EPO Levels

High EPO levels indicate secondary polycythemia. Subsequent evaluation should be aimed at determining the cause. This should include, but not be limited to, the following:

• Measurement of arterial oxygen saturation levels using a pulse-oximeter: low levels would likely indicate a pulmonary or cardiac cause.

• Normal saturation levels could require further evaluation, such as:

  • The use of a co-oximeter to rule out methemoglobinemia

  • Measurement of carboxyhemoglobin levels for smokers

  • Measurement of the P50 of Hb to detect high-affinity hemoglobinopathies

  • Relevant investigations to detect a possible EPO-secreting tumor

Serum Ferritin, Vitamin B12, and Folate Levels

Low serum ferritin and low folate levels have been associated more with primary polycythemia. [4] Raised vitamin B12 levels, often striking, may be observed. This occurs due to increased transcobalamin III secretion by leukocytes. 

Assessment of Renal Function

Renal function abnormalities indicate a higher likelihood of secondary polycythemia. Uric acid levels are often raised due to increased cell proliferation and subsequent turnover.

Assessment of Hepatic Status

Liver cirrhosis and inflammatory liver disease have been associated with secondary polycythemia and increased RBC proliferation.[4]

Ultrasound

An ultrasound and Doppler study of the abdomen would help identify a secondary cause.

In cases of suspected secondary polycythemia, the utility of additional investigations such as a chest radiograph, lung function tests, sleep studies, and an echocardiograph are to be considered as appropriate.

Treatment / Management

The treatment of secondary polycythemia is directed at correcting the cause.

For polycythemia vera, available treatment modalities include:

Phlebotomy

Phlebotomy was established as the backbone of therapy, primarily based on the trial conducted by the Polycythemia Vera Study Group (PVSG). The study found that, compared to chlorambucil or radioactive phosphorous treatment, treatment with phlebotomy alone was associated with longer median survival.[9]

The rationale behind repeated phlebotomies was that cytoreduction would reduce hyperviscosity. Additionally, it would induce a state of iron deficiency that would help retard red-cell proliferation.

In practice, weekly sessions are conducted, during which approximately 500 mL of blood is removed, provided the hemodynamic status permits this.

This is continued weekly until a target hematocrit of under 45% is obtained. This target was determined based on the findings of the CYTO-PV trial conducted in Italy. Investigators observed significantly lower rates of cardiovascular deaths and major thrombotic episodes in patients kept under this threshold.[10]

For secondary polycythemias, phlebotomy is usually reserved for the following conditions:[11]

• Chronic lung diseases

• Cyanotic heart diseases

• Post-renal transplant patients with hypertension and erythrocytosis, not responding to optimal doses of angiotensin-converting enzyme inhibitors (ACEIs)/angiotensin receptor blockers (ARBs)

Hydroxyurea

Hydroxyurea is usually considered second-line therapy. Evidence of benefit came from, among others, a study by the Polycythemia Vera Study Group (PVSG) that showed lower rates of thrombosis compared to a historical cohort treated with phlebotomy alone.[12] Despite theoretical concerns, studies have not found a significant association between the use of hydroxyurea and an increased risk of leukemic transformation.[13] Indications for use include:

• Poor venous access

• High phlebotomy requirement

• When phlebotomy is not possible due to logistic reasons

• Severe thrombocytosis

• Intractable pruritus

The standard daily doses range from 500 to 1500 mg per day.

Doses are adjusted to target platelet counts below 500,000/mcL. However, it is necessary to adjust doses such that the absolute neutrophil count remains above 2000/microliters.

Ruxolitinib

The JAK2 inhibitor ruxolitinib is used when patients are intolerant or unresponsive to hydroxyurea.

Evidence supporting the use of Ruxolitinib in myeloproliferative disorders came from the COMFORT trials. The COMFORT-I study compared the efficacy of Ruxolitinib with placebo therapy, whereas COMFORT-II compared it with the “best available therapy.” Both trials showed a significant reduction in splenomegaly, improvement in symptoms, and better survival.[14][13][14]

However, despite this enhanced benefit, the use of ruxolitinib was associated with increased risks of anemia, often dose-limiting, and thrombocytopenia.

The standard recommended dose for polycythemia vera is 10 mg twice a day.

Dose reduction is required if hemoglobin drops to below 12 gm/dl.

A fall in hemoglobin to below 8 gm/dl indicates that dosing is to be temporarily interrupted.

Low-Dose Aspirin

The original PVSG trial showed that, despite greater longevity, patients treated with phlebotomy alone were at a greater risk of developing thrombosis during the first three years of therapy. This seemed to suggest a potential benefit to concurrently using antiplatelet or anticoagulant agents. Initial trials using higher doses of aspirin or dipyridamole showed unsatisfactory gastrointestinal hemorrhage. However, subsequent studies found that lower doses of aspirin could be safely used.[15]

Currently, aspirin is indicated when there is inadequate control of microvascular symptoms after achieving the target hematocrit or in the presence of other cardiovascular risk factors.

Aspirin, when indicated, is recommended to be used at low doses, ranging from 40 to 100 mg daily.

Hypouricemic Agents

Agents such as allopurinol and febuxostat may be required in cases with significant hyperuricemia. Recent studies indicate that, between them, allopurinol may be a safer alternative with respect to all-cause and cardiovascular mortality.[16]

Management of Pruritus

Depending on the severity of pruritus and the clinical response to therapy, therapeutic modalities available for symptomatic relief include antihistamines[17] and selective serotonin reuptake inhibitors (SSRIs). [18]

Management of Polycythemia Vera in Pregnancy

The standard therapeutic measures of phlebotomy and low-dose aspirin are appropriate in most cases. Certain high-risk women may require the addition of pegylated interferon (IFN)-alpha.[19]

Management of Neonatal Polycythemia

Most patients do not need treatment. Exchange transfusion is occasionally required due to hyperviscosity.

Differential Diagnosis

• Primary myelofibrosis

• Chronic myeloid leukemia

• Essential thrombocythemia

• EPO receptor mutations

Prognosis

Studies estimate the median survival in cases diagnosed with polycythemia vera to be approximately 14.1 years.[13]

Factors that were found to correlate with better prognosis included:

Factors associated with worse outcomes included:

• Higher leucocyte counts

• Venous thrombosis

• Leukoerythroblastic blood smear

Complications

Secondary polycythemia is associated primarily with complications arising from hyperviscosity. Polycythemia vera is associated with complications associated with an increased risk of thrombosis and progression to malignant conditions.

Commonly encountered complications include:

1. Bleeding: Recurrent epistaxis or GI bleeding is often seen, which may lead to iron deficiency anemia, potentially confounding clinical findings, including bone marrow appearance.

2. Thrombosis: Due to hyperviscosity, there is a preponderance of both arterial and venous thrombosis. Manifestations of arterial thrombosis include digital infarcts, and cerebral ischemic infarcts, particularly in watershed territories. Venous thrombosis, such as Budd-Chiari syndrome, is also seen.

Progression to leukemia, particularly acute myeloid leukemia (AML), is seen in approximately 5% of cases and is often refractory to treatment. Studies have implicated the use of chlorambucil, pipobroman, or radioactive phosphorous as factors that increase the likelihood of progression.

Consultations

 A hematologist consultation should be sought in all cases of suspected primary polycythemia.

Deterrence and Patient Education

Patients must be encouraged to stop smoking. Genetic counseling must be offered to the families of those with hemoglobinopathies. Patients with polycythemia vera must be discouraged from donating blood. Because this is a myeloproliferative disorder, blood from donors with polycythemia vera is not considered appropriate for donation in most countries.

Enhancing Healthcare Team Outcomes

Polycythemia can affect every organ in the body, and the symptoms are primarily related to impaired oxygen delivery and blood hyperviscosity. The condition is primarily managed by the hematologist, but managing complications requires an interprofessional team comprised of clinicians, specialists, nursing staff, pharmacists, and phlebotomists. Patients need to be educated by clinicians about the potential complications and when to seek medical assistance. Pharmacists will help manage medication regimens, verify dosing, check for interactions, and offer patients medication counseling. Nurses will assist in patient evaluation, counsel patients about their condition, answer patient questions, and serve as coordinators for the activities of the various disciplines covering the case. The interprofessional model requires open communication among all care team members, including accurate record-keeping. This approach will result in improved patient outcomes. [Level 5]

While survival has improved over the past three decades, the aim is also to maintain quality of life. Apart from thrombotic complications, there is also an increased risk of bleeding as well as a risk of infections. Finally, patients should be made aware that they need lifelong follow-up as there is a risk of progression to acute leukemia or myeloproliferative syndrome. The nursing staff should coordinate and monitor close follow-up and assist in educating the patient and family to ensure regular care is obtained. [21] [Level 1]

Review Questions

• Access free multiple choice questions on this topic.

• Comment on this article.

References

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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*

*Hereinafter

• 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.

Erythrocytes

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.

Hematocrit

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 – 37	30 – 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 conventional 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.

MCV

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 – 85	73 – 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.

A complete blood count, or as it is also called a clinical blood test, is one of the most commonly prescribed tests. The doctor may offer you to donate blood if it is a protracted cold, during a preventive examination, as one of the diagnostic measures in consultation with a narrowly specialized specialist, preparation for surgery, to monitor the treatment process, etc.

Consider the main indicators included in the complete blood count, what each of them means and what the increase or decrease in the indicators of the general blood test indicates.

• Hemoglobin (HGB) is a special protein that transports oxygen. Hemoglobin levels are low in anemia. In this case, a person feels increased fatigue, does not tolerate physical activity. Elevated hemoglobin levels can occur if a person is dehydrated. For example, it loses moisture due to diarrhea with increased urination or, for example, increased sweating in a hot climate leads to an excessive increase in hemoglobin.
• Red blood cell count (RBC). Erythrocytes are red blood cells. A low red blood cell count is indicative of anemia. A reduced level can be when a person takes a large volume of water – two liters or more in a very short period of time, this is called a hypervolemic shock. During the intake of large amounts of water, the blood becomes liquid and the level of red blood cells decreases. An increased level of red blood cells occurs in inflammatory processes in the human body or in conditions of the body associated with dehydration.
• The color index of blood is the ratio of the hemoglobin level to the level of erythrocytes. This indicator is lowered with iron deficiency anemia. An elevated color index can indicate both B12 deficiency anemia and folate deficiency anemia.
• Hemocrit – an indicator of the ratio of blood cells, i.e. blood cells and blood plasma. Decreased hematocrit can occur if the person has had any bleeding or if the patient has an infectious disease. Elevated hematocrit levels are indicative of thickening of the blood, a condition that occurs when the body loses excess fluid, which can occur when vomiting occurs or occurs in people with diabetes.
• Platelets (PLT) – blood cells responsible for its coagulation. A low level of platelets occurs in pregnant women, with anemia and a number of other diseases. Elevated platelet levels occur in inflammatory diseases, some oncological diseases, and in various inflammatory processes in the body.
• Leukocytes (WBC) – white blood cells, cells that are responsible for our immunity. A low level of leukocytes occurs with a number of oncological diseases, with the use of certain drugs that reduce immunity, such as cytostatics. Elevated levels indicate infectious and inflammatory diseases.
• Lymphocytes are one of the types of leukocytes responsible for the immune response. Below normal, the level of lymphocytes decreases with prolonged stressful conditions of the body, with suppression of immunity, when taking corticosteroids – preparations of similar hormones of the adrenal glands. Elevated levels of lymphocytes indicate the presence of infectious diseases when the body is trying to fight the infection.
• ESR – erythrocyte sedimentation rate – an indicator that characterizes the presence or absence of inflammatory processes in the body. If the ESR is below normal, this indicates a thickening of the blood. If the ESR is high, this indicates the presence of an inflammatory process. In this case, the erythrocyte sedimentation rate increases
• Eosinophils – eusonophilic granulocytes – a type of leukocyte. If the eosinophil count is elevated, this may indicate allergic diseases or the presence of worms.

Indicators of the general blood test norm:

Indicators	Sex, age	Norm
Hemoglobin	Men Women Children 7-12 years old	130-160g/l 120-140g/l 110-145g/l
Erythrocytes	Men Women Children 7-12 years old	4.0-5.1×1012 3.7-4.7×1012 3. 5-4.7×1012
Color index		0.85-1.15
Platelets	Men, Women Children 7-12 years old	180-320×109 160-380×109
ESR	Men Women Children 7-12 years old	1-10mm/h 2-15mm/h 4-12mm/h
Leukocytes	Men, Women Children 7-12 years old	4.0-9.0×109 4.5-10.0×109
Eosinophils	Men, Women Children 7-12 years old	0-5% 0.5-7%
Lymphocytes	Men Women Children 7-12 years old	18-40% 24-54%

Preparation for the general blood test:

• The test is taken in the morning, on an empty stomach. The last meal should be 8, and ideally 12 hours before the start of the analysis.