Hematology

What are the benefits of measuring blood?

It can provide information on processes that aren’t observed externally. It is quick/non-invasive and can be sampled repeatedly over time to assess change.

What is the difference between plasma and serum?

Plasma contains fibrinogen (anticoagulant) and serum is liquid portion of blood remaining after clotting.

What is plasma made out of?

90% water, 8% protein, and other substances like lipoproteins, minerals, and glucose.

Buffy coat consists of what cells?

White blood cells

RBC (erythrocytes) function?

Responsible for oxygen transport.

WBC Function?

Involved in immune function.

Platelets

Essential for blood clotting

Where are erythrocytes produced (erythropoiesis) and what is it stimulated by?

In the bone marrow of hematopoietic stem cells. EPO (Erythopoietin) is released mainly from the kidney.

How long does it take for reticulocytes to mature into erythrocytes?

1-2 days.

High reticulocyte counts indicate increased what?

Erythropoiesis

What is the RBC’s lifespan?

Around 100-120 days.

What are RBCs recycled by?

Macrophages in the spleen/liver.

What does we use to measure hematocrit?

% of RBC volume/total blood volume in mL or microL

How do we measure hemoglobin?

RBC size where 97% of dry weight is hemoglobin that allows for oxygen transport.

Anemia is defined as what?

Condition based on Hematocrit (Hct) or Hemoglobin (Hb) values falling below specific thresholds.

Clinical Signs of Anemia

Hypotension, Pale skin, headaches, fatigue, heart palpitation, irritability, muscle aches.

Is MCV, MCH, and MCHC used to diagnose anemia?

No

How to calculate (micro)hematocrit?

RBC height/Total height in Centrifuged tube.

Do hematocrit references vary by age?

Yes.

What part of blood volume increases during pregnancy?

Plasma volume.

How can hemoglobin be measured?

Photometry where erythrocyte lysis releases HgB, which converts into a stable forms that absorbs light at a specific wavelength then determine how much of the hemoglobin can absorb light.

What can be a cause of decreased cell numbers in RBC?

Acute blood loss, hemolysis

What can be a cause of increased cell numbers in RBC?

Erythopoietin Administration

What can be a cause of decreased cell size in RBC?

Loss of iron or hemoglobin defect

What can be a cause of increased cell size in RBC?

Folate/B12. A deficiency can lead to anemia.

How does HgB and Hct change during a change in RBC shape?

They both decrease.

When one is dehydrated, how is the plasma volume/HgB/HcT changed?

The plasma volume decreases and hemoglobin/hematocrit increases (concentrated).

When one is overhydrated, how is the plasma volume/HgB/HcT changed?

The plasma volume increases and hemoglobin/hematocrit decreases.

Changes in plasma volume during pregnancy is most similar to what state?

Overhydration.

RBC Shape can be changed by what?

Inherited disorders like sickle cell disease.

How do osmotic changes affect Hb and Hct?

Hyperglycemia can affect cell volume

What are the measurement errors that can affect Hb and Hct measurements?

Phlebotomy errors (milking), hemolysis (extra interstitial fluid), incorrect centrifugation, instrument calibration that can cause lipemia (high lipid content).

How does lower oxygen pressure affect RBC production, HgB/Hct?

It increases erythropoiesis and increases Hb and Hct. It is harder to detect anemia prevalance with populations living at elevation.

How does smoking affect HgB/Hct?

Chronic smoking can lead to increased Hb and Hct as a compensatory mechanism.

What are anemia cutoffs based off of?

A reference population; it does not determine an individual’s oxygen transport capacity in relation to their oxygen needs.

What are the other causes of anemia other than iron deficiency?

Decreased RBC Production, Increased hemolysis, blood loss.

Decreased RBC Production causes

Nutrient deficiencies (iron, folate, B12), bone marrow diseases, hemoglobin disorders.

Increased RBC Destruction (Hemolysis) causes

Sickle cell disease, malaria, certain diseases or toxins.

Blood Loss causes

Trauma, gastrointestinal bleeding, childbirth, menstruation, parasitic infections.

What is hypoproliferative classification?

Decreased RBC production from nutrient deficiencies

What is maturation defect classification?

Impaired RBC development (e.g., megaloblastic anemia)

What is hemolytic classification?

Increased RBC destruction

What is used to characterize anemia and narrow down potential causes of CBC?

MCV (mean corpuscle volume)

RDW (red cell distribution width)

MCH (mean corpuscular hemoglobin)

MCHC (mean corpuscular hemoglobin concentration)

Red Cell Distribution Size Description

Should be relatively homogenous, with a narrow and symmetrical distribution around the mean.

MCV represents what?

Average volume of RBCs.

When MCV is microcytic, what is the cutoff?

MCV < 80 fL (e.g., iron deficiency anemia)

When MCV is normocytic, what is the cutoff?

MCV 80-100 fL (e.g; blood loss, hemolysis)

When MCV is macrocytic, what is the cutoff?

MCV > 100 fL (e.g., folate or B12 deficiency anemia)

What other statistic could be used to describe the population of RBCs?

Coefficient of Variation.

What does Red Cell Distribution Width measure?

It measures the variation in RBC size. A high RDW indicates a wide variation in cell sizes. RDW determines reliability of MCV.

RDW Calculation

Standard deviation of MCV *100/mean cell volume (MCV)

What is the cutoff for normal RDW?

less than or equal to 14%.

Hemoglobin’s role in RBC

Relevant to size and its function (O2 transport).

What does mean corpuscular hemoglobin measure?

Average amount of hemoglobin per RBC.

What factors influence MCH?

Anything that might affect HgB or RBC

MCHC (Mean Cell Hemoglobin Concentration) measures what?

Average amount of HgB in a given volume of packed RBCs.

Possible causes of anemia for someone that is hyperchromic

lypemia or a globin disorder.