Complete Blood Count (CBC) - Quantitative Values for RBC Count

Plasma, buffy coat, and erythrocytes

What are the components of blood (following centrifugation)?

Plasma (55%)

What makes up a majority of the blood?

Leukocytes and platelets

What is found in the buffy coat between plasma and erythrocytes?

Platelets, erythrocytes, and leukocytes

What are the three blood cell lines?

Multipotential hematopoietic stem cell (hematocytoblast)

What is the origin of all blood cells?

Common myeloid progenitors or common lymphoid progenitors

Multipotential hematopoietic stem cells (hematocytoblasts) can differentiate into...

Megakaryocytes, erythrocytes, mast cells, and myeloblasts

What can common myeloid progenitors differentiate into?

Thrombocytes

Small extensions from the membranes of megakaryocytes

Basophils, neutrophils, eosinophils, and monocytes

What can myeloblasts differentiate into?

macrophages

Monocytes can mature into...

natural killer cells or small lymphocytes

Common lymphoid progenitors can differentiate into...

T lymphocytes or B lymphocytes

Small lymphocytes can differentiate into...

plasma cells

B lymphocytes can mature into...

No

Do erythrocytes have a nucleus?

Optimizes flexibility and surface area for gas exchange

Erythrocytes are bi-concave. Why?

Protein called hemoglobin

What do erythrocytes carry oxygen on?

About 120 days

What is the average lifespan of an erythrocyte?

RBC count, hemoglobin (Hgb), and hematocrit (Hct)

What values in a CBC reflect erythrocyte quantity?

Mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and red blood cell distribution width (RDW)

What values in a CBC reflect RBC quality?

Number of circulating RBCs in one cubic mm of blood

What does an RBC count measure?

4.7-6.1 x 10^6/µL

Normal range of RBCs in men

4.2-5.4 x 10^6/µL

Normal range of RBCs in women

Fatigue, pale conjunctiva and mucous membranes, and chronic bleeding

What are signs and symptoms of decreased RBC counts?

4 subunits (2 alpha and 2 beta)

Hemoglobin is made up of...

250 million

How many molecules of hemoglobin are there per RBC?

One billion (250 molecules of hemoglobin and 4 subunits per hemoglobin, each carrying one)

How many molecules of oxygen does an RBC carry?

total amount of hemoglobin in the blood

A hemoglobin measure is a measure of...

14g of Hgb/dL blood

What would a hemoglobin of 14 indicate?

It serves as the vehicle for transport of O2 and CO2 (so it determines the O2 carrying capacity of the blood) and too little or too much causes problems

What is the purpose of measuring Hgb (hemoglobin)?

RBC count

Hgb can serve as an indirect measure of...

anemic

Hgb can let us know when a patient is...

continuing to bleed

Serial Hgbs help let us know if someone is...

Slightly lower than normal

What variation in older individuals is seen in Hgb?

Higher than normal

What variation in Hgb is observed in younger individuals?

Higher than women

What variation in Hgb is observed in men?

No menstruation and testosterone stimulates release of erythropoietin from kidneys

What causes a higher than normal Hgb in men?

Lower than men

What variation in Hgb is observed in women?

Lower than normal

What variation in Hgb is observed in pregnant women?

Blood volume increases so Hgb is diluted

What is the cause for a lower Hgb in pregnant woman?

Different ranges for different ages

What variation in Hgb is observed in kids?

13.5-16.5 g/dL blood

What is the normal Hgb for a male?

12.0-15.0 g/dL blood

What is the normal Hgb for a female?

10-15 g/dL blood

What is the normal Hgb for a pregnant female?

Volume contraction/dehydration and erythrocytosis

What causes pathologic increases in Hgb?

When there is decreasing blood volume/dehydration, the total RBC count stays the same, so the percentage of RBCs that make up that volume increases, which increases Hgb

Why does volume contraction/dehydration cause a pathologic increase in Hgb?

GI losses (vomiting, diarrhea) and burns

What can contribute to volume contraction/dehydration?

Physiological response to environment such as high altitude; diseases such as congenital heart disease, severe COPD, and polycythemia vera; and smoking

What can cause erythrocytosis, leading to an increased Hgb?

Less oxygen = more RBCs produced to compensate = more Hgb

Why does high altitude lead to an increase in Hgb?

Cyanotic heart disease leads to low oxygen = more RBCs produced = more Hgb

Why does congenital heart disease lead to an increase in Hgb?

It causes an unregulated production of RBCs from bone marrow = more Hgb

Why does polycythemia vera lead to an increase in Hgb?

Carbon monoxide binds to hemoglobin, preventing oxygen from binding, which leads to hypoxia and a subsequent increase in RBC production = more Hgb

Why does smoking lead to an increase in Hgb?

Loss of RBCs, decreased production of RBCs, and dilution

What causes a pathologic decrease in Hgb?

Hemorrhage, hemoglobinopathies, anemias/hemolytic anemias, and prosthetic valves

What are some conditions that lead to a loss of RBCs, which decrease Hgb?

Bone marrow failure, dietary deficiencies, anemias, renal disease, rheumatological diseases, and hematologic malignancies

What are some conditions that can lead decreased production of RBCs, which decreases Hgb?

Cirrhosis of the liver and fluid overload

What are some conditions that lead to dilution of RBCs, leading to decreased Hgb?

If persistently above normal and not normalized with hydration, determine cause of erythrocytosis

When should you act on an abnormally high Hgb and what should you look for?

If persistently below normal

When should you act on an abnormally low Hgb?

<8.0g/dL

At what Hgb value is a transfusion considered (critical value)?

True

T/F? The Hgb value varies between patients, as a healthy individual could tolerate a lower value, while someone with COPD may receive a transfusion at a higher value

% of blood volume made up by RBCs

What is hematocrit (Hct) a measure of?

45% of their total blood volume is made up of RBCs

If a person's Hct is 45%, what does that mean?

Its a direct measure of RBC number and volume and can indicate anemia, erythrocytosis, dehydration, or hemodilution

What is the importance of measuring hematocrit?

Serial values determine if a hemorrhage has stopped, it can help evaluate anemia, and it can determine if a transfusion is necessary

What are some ways Hct values are interpreted?

45%

What is a normal Hct?

Men have higher normal value

How does gender affect Hct normal values?

Younger individuals have higher value and older individuals have slightly lower value

How does age affect Hct normal values?

Lower values due to chronic hemodilution

How does pregnancy affect Hct values?

41.5%-50.4%

Normal Hct for men

36%-45%

Normal Hct for women

RBC x 3 = hemoglobin and hemoglobin x 3 = hematocrit

What is the "general rule of 3"?

Same as those that affect Hgb

What condition(s) cause an increase or decrease in Hct levels?

<21%

Value considered a critically low Hct

>65%

Value considered critically high Hct

Percentage of immature RBCs on a peripheral smear with Wright or Giesma staining

What does a reticulocyte count measure?

Bone marrow's ability to respond to anemia and make RBCs

What does a reticulocyte count indicate?

It factors in a patient's Hct and a normal Hct because reticulocyte count depends on the total number of RBCs.

In anemic patients, they can have a low retic count, but also a low RBC count, which makes the retic count falsely high

What is the purpose of the reticulocyte index, particularly in individuals with anemia?

0.5%-2% of total RBCs

What is a normal reticulocyte count?

Infants or newborns

A reticulocyte count is higher in what individuals?

1.0

What is a normal reticulocyte index?

Production of RBCs by the bone marrow has increased

An increased reticulocyte count/index indicates what?

Hemolytic anemia, hemorrhage, hemolytic disease of a newborn, and starting treatment with iron, vitamin B12, or folate deficiencies

What are potential causes for the bone marrow to increase RBC production, leading to higher retic counts?

All are important for making RBCs, and the bone marrow responds to increased levels of them

Why does the reticulocyte count/index increase in response to treatment for iron, vitamin B12, or folate deficiencies?

Any condition that suppresses production of RBCs at the level of the bone marrow

What leads to decreased reticulocyte counts/indices?

Bone marrow failure, aplastic anemia, pernicious anemia/folic acid deficiency, iron-deficiency anemia, radiation therapy, malignancies, adrenocortical hypofunction, anterior pituitary hypofunction, and chronic diseases

What are a few conditions that can lead to decreased reticulocyte counts?