Anemias and blood disorders Flashcards
What are the 4 stages of a clot formation?
1) vasocontriction 2) platelet plug formation 3) Coagulation 4) fibrinolysis
what occurs during the vasoconstriction stage of clot formation?
Diminishes blood flow and loss
What do platelet granules relase to induce vasoconstriction during clot formation?
Serotonin
What three factors occur to allow a platelet plug formation to occur?
1) collagen 2) ADP 3) Thromboxane A2
What does collagen do to help create a platelet plug?
Collagen promotes the platelets to adhere d/t vWF
What is vWF?
Von willebrand factor which is the portion of the platelet that causes adhering of the platelet to the damaged area
What does ADP do to help create a platelet plug?
ADP attracts more plateles
What does Thromboxane A2 do to help create a platelet plug?
thromboxane promotes aggregation, degranulation and vasoconstriction
what is the most common inherited bleeding disorder?
Von willebrand disease (lack of vWF)
What are the two pathways of the coagulation stage of a clot formation?
intrinsic (APTT) and extrinsic pathway (PT)
what happens in the fibrinolysis phase of the clot formation?
Plasminogen is activated by plasminogen activators (both nonfibrin-specific or less fibrin-specific) in order to degrade fibrinogen
What kind of condition occurs when fibrinolysis is compromised?
An emergency situation
what basic routine laboratory test categories can be used to evaluate the ability to form a clot?
1) vasocontriction 2) platelet plug formation 3) Coagulation
what basic routine laboratory tests can be used to evaluate the vasoconstriction ability to form a blood clot?
none
what basic routine laboratory tests can be used to evaluate the platelet plug formation ability to form a blood clot?
1) Platelet Count 2) Bleeding Time (BT)
what basic routine laboratory tests can be used to evaluate the coagulation ability to form a blood clot?
1) Prothrombin Time (PT) 2) (activated) Partial Thromboplastin Time (APTT, PTT)
Is blood clotting the same as coagulation?
No, coagulation is a phase of blood clotting
What category of basic laboratory test is used to evaluate the ability to remove a blood clot when it is no longer needed?
Fibrinolysis
What fibrinolysis category basic laboratory test is used to evaluate the ability to remove a blood clot when it is no longer needed?
Fibrin degradation products (FDP, D-dimer)
What type of test is a bleeding time?
primarily a platelet function test
What does the bleeding time evaluate?
Evaluates interaction of platelets with vessel wall and formation of the platelet plug
Does the bleeding time function dependent of coagulation or independent of coagulation?
functions independent of coagulation
What condition will prolong bleeding time?
Thrombocytopenia (<100K, definitely , 50K)
What must be established in order for a bleeding time to be used as a platelet function test?
a normal platelet count must first be established
will the bleeding time remain normal in hemophilia?
Yes
what term is used to decribe an increased amount of time over normal for any “time” test?
Prolonged time
what aspect can affect BT?
Vasoconstriction capabilities therefore it is not suited for patients with senile skin changes
what are the two routine methods of performing a BT?
1) Duke Bleeding Time 2) Ivy Bleeding Time
Where does the stab wound occur in the Duke Bleeding Time?
stab wound to the ear lobe
Where does the stab wound occur in the ivy Bleeding Time?
more standardized method of incision to the forearm
what are some factors that may affect Bleeding time?
1) Poor vascular function 2) Depth of incision 3) Touching incision 4) ETOH consumption 5) Aspirin consumption (5 days after one 300 mg dose)
What are the most common causes that prolong the bleeding time?
1) Quanitative platelet abnormalities (thrombocytopenia) 2) Qualitative platelet abnormalities (platelet function) 3) loss of capillary integrity
what are two reasons for thrombocytopenia?
1) Reduced production in the bone marrow 2) destruction of platelets outside the bone marrow (intravascular or intrasplenic)
What would be the cause of qualitative platelet abnormalities (platelet function)?
von willebrand’s disease
What would be the cause of qualitative loss of capillary integrity?
1) collagen vascular diseases 2) Senile capilary fragility
What is a platelet count?
part of a routine CBC
When will spontaneous bleeding occur due to platelet count issues?
Anytime platelet count falls below 40-50K
What is the most common cause of thrombocytopenia?
1) Reduced production in the bone marrow 2) destruction of platelets outside the bone marrow (intravascular or intrasplenic)
what can cause a reduced production of platelets in the bone marrow?
1) Bone marrow malignancies (both primary and metastasis destroys normal bone marrow) 2) Toxic effects of drugs, chemicals and microorganisms 3) Factor deficiencies (B12 and folate)
can thrombocytopenia cause spontaneous bleeding?
No, it just prevents clotting
what can cause an increased destruction of platelets outside the bone marrow?
Intravascular and intrasplenic immune reactions (ie: idiopathic thrombocytopenic purpura)
What is an activated partial thromboplastin time?
The time it takes a plasma specimen to yield a fibrin clot once the intrinsic Pathway is initiated
What is the difference between APTT and PT?
APTT is a screening test of the intrinsic pathway whereas PT is a screening test of the extrinsic pathway
A patient on what medication will require an APTT to monitor their condition?
patients on therapeutic heparin for monitoring purposes
What are the most common causes of prolonged APTT?
1) congenital coagulation factor deficiencies 2) Acquired coagulation factor deficiencies 3) Anticoagulant medications
What congenital coagulation factor deficencies can prolong APTT?
Hemophilia A and B
What factor is Hemophilia A deficient?
Factor VIII
What factor is Hemophilia B deficient?
factor IX
What is an acquired coagulation factor deficiencies that can commonly cause prolonged APTT?
Chronic liver disease (hepatic insufficiency results which implies liver damage is beyond repair)
What anticoagulant medications commonly cause prolonged APTT?
Heparin and coumadin (PT is better)
What is a Prothrobin time (PT)?
The time it takes a plasma specimen to yield a fibrin clot once the extrinsic Pathway is initiated
What is an INR?
International Normalized ration (INR) which uses the PT and creates a ratio to account for inter-laboratory variability in PT
What are the most common causes of a prolonged PT?
1) Congenital coagulation factor deficiencies 2) Acquired coagulation factor deficiencies 3) Anticoagulant medications 4) Vitamin K deficiency
What congenital coagulation factor deficencies can prolong PT?
The only factor is VII and it is uncommon
What acquired coagulation factor deficiences can commonly cause a prolonged PT?
chronic liver disease
what will prolong earlier due to liver disease, PT or APTT?
PT prolongs before the APTT
what anticoagulant medications commonly cause prolonged PT?
coumarin (using the INR)
What are the 2 ways in which we have the inability to regulate hemostasis?
- Hemorrhage. 2. Thrombosis.
What type of state is thrombosis?
Hypercoagulable state.
what is a D-Dimer assay?
D-Dimer is a fibrin degradation product
what is D-Dimer used for?
As a screening tool for DVTs
What is the definitive diagnosis of DVT?
venous scanning procedures
when should patients be referred for a venous scanning procedure?
When there is an increased level of D-Dimer in a patient
During what treatement is a d-dimer helpful for monitoring possibility of recurrence of DVTs?
When determining length of anticoagulant treatment.
What are the 2 categories of bleeding disorders?
- Coagulation associated bleeding. 2. Platelet associated bleeding.
What are the 2 types of coagulation associated bleeding?
Inherited and acquired.
How can you tell if a bleeding condition is congenital?
most of the major congenital bleeding disorders are coagulation- associated disorders. Congenital disorders tend to manifest earlier in life.
How should a new vs old bleeding disorder be treated?
New- immediate diagnostic and treatment preferably by a specialist. Old- careful monitoring but no further diagnostic testing.
What is the difference between provoked and spontaneous bleeding?
Spontaneous (unprovoked) bleeding is a serious situation and requires immediate emergency medical referral whereas provoked bleeding is bleeding associated with trauma or surgery that is out of proportion to that expected from the trauma or surgery
Coagulation-associated bleeding is usually bleeding where?
Into joints.
What is bleeding in joints called? What can repeated joint bleeding cause?
Hemarthrosis. Can cause degeneration as an arthritic change.
Platelet-associated bleeding is usually what?
Mucous membrane, or mucocutaneous bleeding or brusing.
Name different types of brusing?
Petechiae, ecchymosis, purpura.
Genetic bleeding disorders tend to be what type of inheritance?
Sex-linked.
How can drugs/ medications cause bleeding disorders?
Asprin or certain NSAIDs cause platelet function to be altered. Some drugs can suppress bone marrow production of platelets. Platelet function or production may be affected via idiosyncratic drug reactions.
Name systemic diseases that might cause bleeding disorders?
Recent infections, presence of other hematologic diseases, nutritional deficiencies, autoimmune diseases, liver diseases.
What are signs and symptoms of other hematologic disorders?
Anemia, lymphadenopathy, splenomegaly, bone pain.
Name the 3 congenital coagulation-associated bleeding disorders?
Hemophilia A, Hemophilia B, Von Willebrand’s disease.
What causes Hemophilia A and B?
A- factor VIII:C deficiency. B- factor IX deficency aka christmas factor.
What is the most common severe of the 3 congenital coagulation-associated bleeding disorders?
Hemophilia A.
What is the most common of the 3 congenital coagulation-associated bleeding disorders?
von Willebrand’s disease is the most common inherited hemostatic disorder.
Of the 3 congenital coagulation-associated bleeding diseases will they effect males or females more?
Hemophilia A and B more males. vWD- males equal females.
Where will bleeding most commonly occur at with hemophilia A?
Anywhere, but most commonly into large weight bearing joints (knees, ankles, elbows) and soft tissues.
What are the types of hemophilia A?
Severe, moderate, mild and they depend on the amount of factor VIII:C that is missing.
How common are the 3 types of hemophilia A and what are they like?
Severe (<1%)- evident early in life, spontaneous bleeding for no apparent reason. Moderate (1-5%)- not appatent until child attempts to place weight on large joints. Mild (5-30%)- not noticed until after trauma or surgery.
What is a PT test?
Prothrombin test- testing the extrinsic clotting pathway.
What is a APTT test?
Activated partial thromoplastin time- testing the intrinsic clotting pathway. AKA PTT.
What is a BT test?
Bleeding time- assess platelet function.
What is a platelet count test?
Just a count of total platelets done with a BT test (before you can know if the platelets are functioning normaly you need to know if you have a normal amount).
What are the lab findings for hemophilia A?
Normal- PT, Platelet count, and BT. Prolonged PTT.
With hemophilia A and B will they be caused by factor deficiencies or abnormal functioning factors?
A- deficiency and rarely due to abnormal function. B- 2/3 is deficiency and 1/3 is abnormal function.
What is the most common inherited hemostatic disorder?
Von Willebrand’s Disease
What will the lab findings be for hemophilia B?
Normal- PT, Platelet count, and BT. Prolonged PTT. Same as hemophilia A and they are genetically similar.
vWD is what type of abnormality? Caused by what?
Coagulation and platelet function due to dyfunctional or deficient von willebrand’s factor.
What is the purpose of von Willebrands factor?
mediates platelet adhesion and preserves VIII:C from degradation.
The greater majority of vWD patients only manifest what?
Platelet-associated bleeding (mucocutaneous bleeding - epistaxis, gingival bleeding, menorrhagia; occasional GI bleeding and rarely hemarthrosis)
How many types of vWD are there and which one is most common?
5 subtypes and type I makes up 80%.
What is type I vWD like?
clinically mild quantitative deficiency in vWF.
The most common vWD patient will display what type of bleeding?
Mild provoked bleeding following trauma, surgery, and dental extractions. Some women can have abnormal menstral bleeding.
A type I vWD patient may become more evident when?
With the use of asprin since the asprin will further decrease the platelet’s ability to adhere.
What are the lab results for a vWD patient?
Normal- PT, Platelet count, PTT (rarely prolonged only when VIII:C is <25% of normal and this will not happen with subtype I). Prolonged- BT(occasionally normal, but can be provoked with an asprin challenge).
What are 2 types of aquired coagulation-associated bleeding disorders/
Hepatic insufficiency. Vitamin K deficiency.
What will happen with hepatic insufficiency (Hemostasis related)?
Leads to bleeding tendency due to decreased production of coagulation proteins.
What coagulation factors need Vitamin K?
II, VII, IX, X.
What can lead to vitamin K deficiencies?
Biliary tract disease due to malabsoprtion due to fat absorption problems. Nutritional deficit is rare. Broad-spectrum antibiotics destroy GI flora that normally produce Vitamin K.
Besides coagulation factors what coagulation proteins are important?
Some that inhibit fibrinolysis (continued consumption of coagulation factors).
What causes fibrinogen deficiency?
This is a late effect of a severly compromised liver.
How else will a cirrhotic liver affect hemostasis?
Reduction in thrombopoietin and this leads to thrombocytopenia.
What are the lab findings with early and late hepatic insufficiency?
Early- Normal- APTT, platelet count, BT, prolonged PT. Late- Prolonged PT, APTT, BT, Decreased Platelet count.
What would lab tests be like for a pateint with mild vitamin K deficiency or on theraputic doses of Warfarin?
Both would have normal APTT, Platelet count and bleeding time and Prolonged PT.