Leukocyte CBC Patterns

Leukocytosis

increased total WBC count

For most species, leukocytosis is due to increase in what leukocyte?

neutrophils (since they are most abundant in the blood)

Two types of leukocytosis:

1.) non-pathologic

2.) pathologic

non-pathologic causes of leukocytosis

-stress leukogram

-physiologic leukogram

pathologic causes of leukocytosis

-inflammation

-leukemia (neoplasia)

Leukopenia

decreased total WBC count

For most species, leukocytosis is due to decrease in what leukocyte?

neutrophil

Unlike leukocytosis, leukopenia is always ________

pathologic

Neutrophilia

Segmented neutrophils above reference interval (RI)

Two causes of neutrophilia:

1.) non-pathologic cause

2.) pathologic cause

non-pathologic causes of neutrophilia:

-epinephrine (excitement, exercise)

-corticosteroids (stress neutrophilia)

pathologic causes of neutrophilia:

-inflammation/infection

-neoplasia

Three leukogram patterns:

1.) Stress leukogram

2.) Physiologic leukocytosis

3.) Inflammatory leukogram

Stress leukogram

May have a normal total WBC count or mildly elevated total WBC count; due to increased corticosteroids due to stress

Two causes of a stress leukogram:

1.) endogenous

2.) exogenous

Endogenous increase of corticosteroids

Overproduction of corticosteroids; can also be due to stress or response to illness

Exogenous increase of corticosteroids

excess corticosteroids due to administration of medication, like a steroid

Classic pattern of stress leukogram

-Low Lymphocytes (lymphopenia)

-Low Eosinophils (eosinopenia)

-More Monocytes (monocytosis)

-More Neutrophils (mature neutrophilia)

*LEMN

True or false: a stress leukogram might not always have a classic pattern on CBC

true! may sometimes only have some components (such as only low lymphocytes and low eosinophils)

Why is there a mature neutrophilia (increase) on a stress leukogram (3)?

1.) There will be an increase in neutrophil release from the storage pool into the circulating pool

2.) At the same time, neutrophils in the marginating pool move to the circulating pool

3.) There is also a decreased movement of neutrophils into the tissues

*all of these things cause neutrophil count to increase in the blood (neutrophilia)

Mature neutrophilia (increase) on a stress leukogram is NOT due to what?

increased production

Why does lymphopenia occur with a stress leukogram?

-↑ margination of circulating lymphocytes

-↑ tissue and lymph node sequestration

-↓ bone marrow production, activation, and proliferation

Why does eosinopenia occur with a stress leukogram?

-↑ margination

-↑ tissue sequestration

-↑ apoptosis

-↓ bone marrow production and release

Why does monocytosis occur with a stress leukogram?

↑ mobilization of marginal pool monocytes to circulating pool in blood vessels

Describe the changes seen in this stress leukogram

-leukocytosis

-mature neutrophilia

-lymphopenia

-monocytosis

-eosinopenia

For a stress leukogram, there will be no _________ shift and no _________ change in neutrophils

left; toxic

Physiologic Leukocytosis

physiologic leukocytosis from epinephrine or norepinephrine

Four causes of Physiologic Leukocytosis

1.) excitement

2.) exercise

3.) fear

4.) pain

What species most commonly will have a physiologic leukocytosis?

cats and foals less than 1 year old

Classic pattern of physiologic leukocytosis (2):

-neutrophilia

-lymphocytosis

Why is there a mature neutrophilia for physiologic leukocytosis?

Higher blood flow from epinephrine moves marginal pool neutrophils into the circulation

physiologic leukocytosis is NOT due to what?

increased production or release from the bone marrow

Why does leukocytosis occur with physiologic leukocytosis?

due to release of from the spleen

physiologic leukocytosis has a ________ effect. What does this mean?

transient; epinephrine release only lasts for about an hour and will go back down on repeated blood work

Describe the changes seen in on this CBC from a physiologic leukogram

-mild leukocytosis

-mild mature neutrophilia

-lymphocytosis

For a physiologic leukogram, there will be no _________ shift and no _________ change in neutrophils

left; toxic

Inflammatory leukogram

increased total WBC count is present but leukogram pattern can be variable

Variable pattern of inflammatory leukogram

-usually neutrophilia (sometimes neutropenia)

-sometimes left shift and toxic changes

-maybe monocytosis

An inflammatory leukogram might also have signs of a _________ leukogram. Why?

stress; due to conconcurrent stress

*lymphocytosis or lymphopenia

Whether or not there is neutrophilia or neutropenia with an inflammatory leukogram depends on what factors?

time frame and severity (how fast the bone marrow can respond and how much of a storage pool the bone marrow has)

When would there be neutrophilia on an inflammatory leukogram?

-inflammation causes increase in margination and emigration into tissues to deal with the cause of inflammation

-this stimulates bone marrow to increase in granulopoiesis and production of neutrophils to replace those that went to the tissues

When would there be neutropenia on an inflammatory leukogram?

with severe inflammation/infection

When would there be a left shift on an inflammatory leukogram?

with severe inflammation/infection

An inflammatory leukogram does not always indicate...

infection; means there is inflammation, need to do other things to see if there is an infection occurring

Common causes of inflammatory leukogram

-infectious agents (esp bacteria)

-physical injury

-hemolysis

-immune mediated diseases

-cancer

Inflammatory leukogram for dogs and pigs

marked increase in neutrophils with inflammation

Inflammatory leukogram for cats and horse

intermediate level of neutrophilia with inflammation

Inflammatory leukogram for cows

neutropenia with acute inflammation

Left shift

increased number of immature neutrophils (band neutrophils) due to less mature forms being released with severe inflammation

Two types of left shifts

1.) appropriate (regenerative)

2.) inappropriate (degenerative)

appropriate (regenerative) left shift

segmented neutrophil numbers are greater than immature cells (bands); means that left shift hasn't gotten so out of control that immature cells are more frequent than mature cells

inappropriate (degenerative) left shift

immature cells (bands) are greater than mature segmented neutrophils; indicates that there is severe inflammation present!

Chronic inflammation causes what value on CBC?

chronic inflammatory neutrophilia

Two factors that determine the balance of neutrophil concentration in the blood:

1.) bone marrow delivery

2.) tissue consumption

Five factors affecting magnitude of neutrophil response:

1.) degree of stimulation

2.) rate of tissue consumption

3.) blood marrow reserves

4.) marrow proliferative capacity

5.) species variations in response

Three prognostic indicators of neutrophilia:

1.) magnitude of neutrophilia

2.) degree of left shift

3.) presence and severity of toxic change in neutrophils

If a left shift is more severe, this indicates ________ inflammation

more (inappropriate left shift)

Flowchart for deciding cause of neutrophilia:

First, decide what?

is there a left shift or no left shift?

Flowchart for deciding cause of neutrophilia:

If neutrophilia is due to a left shift, is is caused by...

inflammation

Flowchart for deciding cause of neutrophilia:

If there is no left shift present, then you must decide...

is there lymphopenia or are lymphs normal/moderately increased?

Flowchart for deciding cause of neutrophilia:

If there is lymphopenia present with no left shift, this indicates neutrophilia is caused by...

steroid response

Flowchart for deciding cause of neutrophilia:

If there is no lymphopenia present/moderate increase with no left shift, this indicates neutrophilia is caused by...

excitement response

Leukemoid response

very rare; marked leukocytosis with marked segmented neutrophilia

For Leukemoid response, the segmented neutrophil count will be above ____ x 10^9 L

50

The primary WBCs present for a Leukemoid response are what? Why?

segmented neutrophils; caused by increased granulopoiesis in the marrow due to infection, inflammation, or neoplasia

For a Leukemoid response, there may also be...

a marked left shift with toxic changes

The Leukemoid response is different from...

Leukemia

Differences between Leukemoid response and leukemia: clinical signs

Leukemoid response will have signs of inflammatory disease (such as pyometra) while leukemia will have vague clinical signs (fever, lethargy, anorexia)

Differences between Leukemoid response and leukemia: anemia

Leukemoid response may have mild anemia associated, but there will be a severe anemia with leukemia

Differences between Leukemoid response and leukemia: immature leukocytes

Leukemoid response will not have immature leukocytes in the blood, while leukemia will

Neutropenia

neutrophil numbers below the reference interval

Neutropenia is always __________

pathologic!

If neutropenia is below _____ x 10^9/L, there is a risk of secondary bacteria infection

0.50 x 10^9/L

Three causes of neutropenia

1.) increased consumption of neutrophils

2.) increased margination of neutrophils

3.) decreased or ineffective production

What causes increased consumption of neutrophils, leading to neutropenia? Why?

inflammation/infection; with severe inflammation, tissue demand overwhelms the marrow's ability to respond, so the storage pool of neutrophils is depleted and there is nothing to give to the blood

In what species will neutropenia occur with severe inflammation?

dogs, cats, horses

In what species will neutropenia occur with acute inflammation?

cattle

If inflammation is ruled out as the cause of neutropenia, what should be considered?

bone marrow evaluation to determine if ineffective production is the cause

What causes increased margination of neutrophils, leading to neutropenia?

endotoxemia (endotoxins in the blood)

Why does endotoxemia cause increased margination of neutrophils, leading to neutropenia?

when bacteria produce endotoxins in the blood, initially increased margination of neutrophils occurs, resulting in lower number in the circulating pool (only lasts for 3-5 days)

What causes decreased production of neutrophils, leading to neutropenia?

bone marrow damage or suppression; neutrophil precursors are defective or damaged and die before they are released from bone marrow

With decreased production of neutrophils, there will be a _________ neutropenia

persistent

Examples of diseases that cause bone marrow damage

-FeLV

-PIV

-parvovirus

-bovine viral diarrhea

-Ehrlichia

Examples of other things that cause bone marrow damage

-neoplasia

-chemotherapy drugs

-some antimicrobials

-severe septicemia