lab evaluation of hemostasis

what are the reserve organs of platelets?

1. spleen

2. lung

3. liver

4. bone

where are platelets formed?

bone marrow

if you are looking at a PLT graph it resembles a "ski slope" what does this indicate?

healthy animal

what does it indicate if the PLT slope is flattened/ lumpy?

platelets are clumped

what does it indicate if the PLT has an upward increase?

large platelets are present

what is the clinical approach if you are given a result of thrombocytopenia?

1. Is the thrombocytopenia true?

2. Is it psuedo due to clumping?

3. Check the tube for clots, can rotate in hand for macroscopic view or look at the blood smear for clumps for microscopic view

4. If no clumps or clots present than patient has true decrease in platelet concentration

5. You have accurate thrombocytopenia

what do you advise if platelet clumps are in the body of the smear and feathered edge?

1. Understand that analyzer for platelet concentrations is a minimum (lowest amount of platelets it could count)

2. Understand that platelet estimation number is not always possible due to clumping

3. Consider redrawing the sample if you need a number estimate (maybe first sample was a bad draw or had errors)

what is the healthy platelet count for a dog/cat?

1. 8-10/hpf

2. about 1 platelet/30 RBCs

how do you calculate platelet concentration?

(# of platelets) * 15000

what is the formula for estimate of [platelet]?

number of platelets / hpf field

how many fields should be counted to calculate a platelet average? then what do you do?

1. count 10 fields, calculate an average

2. multiply by 15000/uL

what does the circled image indicate?

activated platelet

what does this platelet curve indicate?

animal is in health

what does this platelet curve indicate?

platelet clumping

what does this platelet curve indicate?

large platelets have formed

what is outlined in the image and what is the function?

• cytoplasmic projections of the activated platelet

• function: helps activate other platelets

what is depicted in the image? what is its function?

• granules secreted and activated

• function: to form platelet plug

what is occurring in the image?

large thrombocytopenia

what is occurring in the image?

medium thrombocytopenia

what tests can we conduct to examine primary hemostasis?

1. BMBT

2. Plt count

3. vWF assays

4. Plt function

what would be occurring in the animal to consider using a test to examine primary hemostasis?

1. thrombocytopenia

2. vWF deficiency

3. abnormal plt function (receptor deficiencies)

what are the causes for psuedothrombocytopenia?

1. large platelets

2. platelet clumping

what species are known to have platelets clump?

1. cat

2. cow

what are other reasons besides breed specificity why platelets may clump?

1. delayed transfer of blood from syringe to tube

2. inadequate mixing

3. old samples > 5 hours

what specific dog breeds have inherited macrothrombocytopenia?

1. norfolk terrier

2. king charles spaniel

what specific species have large platlets?

cats

What answer best matches the image?

thrombocytopenia

What answer best matches the image?

WRI

what are the causes of thrombocytopenia?

1. decreased platelet survival

2. idiopathic or multifactorial

3. decreased production of platelets

4. Sequestration (abnormal distribution)

what leads to decreased production of platelets?

bone marrow disease

what specific infections will lead to bone marrow disease?

1. BVD

2. canine distemper

3. parvovirus

what things (general) can lead to bone marrow disease?

1. drugs

2. infections

3. toxins

4. estrogen, bracken fern poisoning

what are the signs of thrombopoiesis?

LARGE platelets (reactive and immature)

what is the clinical approach if you suspect thrombocytopenia due to marrow disease?

1. blood smear to see if you can see large platelets

2. definitive diagnosis via bone marrow aspirate

what pathogenesis is associated with increased destruction of platelets?

1. Ab-mediated

2. idiopathic

what pathogenesis is associated with increased activation or consumption of platelets?

1. vasculitis

2. DIC

3. endotoxins

what pathogenesis is associated with sequestration?

endotoxins

what pathogenesis is associated with with multifactorial?

1. infectious

2. neoplasia

what is the location and immune cell that corresponds with increased destruction of platelets?

The spleen is the primary location, and macrophages are the immune cells involved in the increased destruction of platelets

what is the pathogenesis of immune-mediated thrombocytopenia (IMT)?

1. formation of anti-platelet antibodies

2. macrophages engulf these organisms leading to decreased [plt]

what shape will the platelets take after IMT?

spherocytes due to macrophages taking portions of membrane of platelet

what can be seen with IMHA?

IMT

what is the pathogenesis of consumptive thrombocytopenia? I did this card as more of a process

1. Damage to endothelium

2. Platelet activation and aggregation

3. overconsumption and removal of blood

A dog’s CBC results included a mild leukocytosis, mild

anemia with schizocytosis, keratocytosis, and

thrombocytopenia (100,000/μL; RI 150,000–450,000).

What is the most likely cause of the thrombocytopenia?

Intravascular consumption of platelets

what is the pathogenesis of infectious canine cyclic thrombocytopenia?

immune-mediated destruction or sequestration

what is the agent for of infectious canine cyclic thrombocytopenia?

Anaplasma platys

what is the vector for infectious canine cyclic thrombocytopenia?

ticks

what is the cyclic aspect of infectious canine cyclic thrombocytopenia?

peak parasitemia followed by thrombocytopenia

what is important to know about the blood analysis of infectious canine cyclic thrombocytopenia?

will not always appear on blood smear

what are specific disease names for of infectious canine cyclic thrombocytopenia?

1. Rickettsial disease

2. anaplasmosis

what is this picture showing?

anaplasma platys inclusion bodies

what are the rules of thumb for hemorrhage and thrombocytopenia?

1. MARKED thrombocytopenia causes hemorrhage

2. hemorrhage does NOT typically mean thrombocytopenia

what must the platelet count be for hemorrhage?

below 20,000

does blood loss cause thrombocytopenia?

usually not, only marked blood loss

how is the severity of hemorrhage reduced in regards to platelets?

shifting platelets from spleen, lung, and possibly liver

thrombocytosis

platelet concentration above reference limit

what is the cause of thrombocytosis?

1. increased production (clonal or non-clonal)

2. redistribution (lungs and spleen)

primary thrombocytosis is…

1. clonal

2. rare hemic neoplasia

what is the concentration of platelets in primary thrombocytosis?

greater than 2x the URL

extreme thrombocytosis

above 1 million

secondary thrombocytosis

• non-clonal

• as a reaction to other conditions (reactive thrombocytosis)

what is the concentration of platelets for secondary thrombocytosis?

less than or equal to 2x URL

what are the causes for increased production of platelets (reactive thrombocytosis)?

1. inflammation

2. iron deficiency

3. recovery from thrombocytopenia

what are the causes for redistribution in thrombocytosis?

1. exercise

2. epinephrine

severe thrombocytopenia can cause…

spontaneous hemorrhage

what must accompany blood loss for it to cause significant thrombocytopenia?

1. sever thrombocytopenia

2. accompanied by anemia

who is the key player in primary hemostasis?

platelets

who is the key player in secondary hemostasis?

coagulation factors

who is the key player in tertiary hemostasis?

1. plasmin

2. t-PA

what is the receptor for vWf?

GP1b

what is the receptor for fibrinogen?

GP2b/3a

vWf is involved in…

platelet adhesion

fibrinogen is involved in…

platelet aggregation

platelet granules contain…

1. ADP

2. TXA2

bernard soulier syndrome

when there is a deficiency of the Gp1b receptor

von Willebrand disease

• deficiency of vWf receptor

• adhesion cannot occur despite platelets having receptors

what breed is associated with von Willebrand disease?

doberman pinscher

glanzmann thrombasthenia

deficiency of Gp2b/3a receptor

what breeds of dog are associated with Glanzmann thrombasthenia?

1. Otterhounds

2. Great pyranees

what animal besides dog is associated with Glanzmann thrombasthenia?

horses

what coagulation factors are associated with the INTRINSIC pathway?

Factors VIII, IX, XI, and XII

what coagulation factors are associated with the EXTRINSIC pathway?

Factor VII

what coagulation factors are associated with the COMMON pathway?

Factors X,V, and II

what coagulation factors are vitamin K dependent?

Factors II, VII, IX, and X

what anticoagulant is in a blue top tube?

citrate

why is citrate used for PT and PTT?

reversibly binds calcium, preventing clotting without damaging clotting factors

what variables do you need for primary hemostasis to occur?

1. adequate number of platelets

2. normal plt function

3. vWF

what would the differential list be for primary hemostasis?

1. thrombocytopenia

2. vWf deficiency

3. abnormal plt functions

what is an analogy that you can use to remember the coagulation factors of intrinsic pathway?

why pay $12 when you can pay $11.98 at walmart

what are clinical signs for primary hemostasis?

1. petichiae

2. mucosal bleeding

3. bloody urine

4. epistaxis

what are clinical signs for secondary hemostasis?

1. hematomas

2. frank bleeding

3. hemothorax

4. hemoabdomen

what are clinical signs of non-specific hemostasis?

1. ecchymoses

2. bleeding after blood draw

3. bleeding following surgery or venipuncture

what tests should you run to confirm that the thrombocytopenia is true?

1. blood smear

2. roll tube

PTT is used for

intrinsic and common pathway

PT and OSPT is used for

extrinsic and common pathway

ACT is used for

intrinsic and common pathway

ACT is a good…

screening test

what is the only factor not evaluated in an ACT test?

factor VII

APTT is used to…

confirm since it is a more sensitive test