Thrombocytopenia and Platelet Disorders Flashcards
What is it?
What 3 mechanisms cause a low platelet count?
Low platelet count
Decreased production
- A problem with the bone marrow
Increased destruction/consumption
- Platelets being used faster than produced
Over-storage (splenic sequestration)
- Pooled in the spleen rather than circulation
Decreased marrow production:
- What type of anaemia can cause this?
- Megaloblastic anaemia - what is it and what causes it?
- What could infiltrate the bone marrow causing suppression? - 2
- What drugs can suppress production? - 4
- What type of deficiency causes this?
- What else which is consumed may lower platelet count?
Aplastic anaemia is a serious condition affecting the blood, where the bone marrow and stem cells do not produce enough blood cells. It is also called bone marrow failure and can happen suddenly (acute) or develop over a period of time (chronic).
Megaloblastic anaemia is characterized by red blood cells that are larger than normal. There also aren’t enough of them. It’s known as vitamin B-12 or folate deficiency anaemia, or macrocytic anaemia, as well. Megaloblastic anaemia is caused when red blood cells aren’t produced properly.
Leukaemia
Myeloma
Cytotoxic drugs
Chemo/radio
Anti-epileptics
Psych drugs
B12 and folate deficiency
Alcohol - can also contribute via liver cirrhosis and portal HTN - spleen
Consumptive Causes:
What 3 haematological emergencies would cause this?
What major illness can also use up platelets?
What 2 organs, when diseased, could lead to this?
DIC
TTP
HUS
Acute leukaemia
Sepsis
Hypersplenism and liver disease
Consumptive causes:
Thrombotic thrombocytopenic purpura (TTP):
- What is it?
- Why does it cause low platelets?
- Why do they get haemolysis?
- What symptoms and signs do they have?
DIC is another cause. What blood test needs to be done to rule this out?
PEOPLE GET REALLY SICK WITH THE ABOVE 2!
A blood disorder in which platelet clumps form in small blood vessels. Blood clots form in small blood vessels throughout the body. The clots can limit or block the flow of oxygen-rich blood to the body’s organs, such as the brain, kidneys, and heart.
The condition uses up the platelets.
In TTP, hemolytic anaemia occurs because red blood cells are broken into pieces as they try to squeeze around blood clots. When TTP is the cause of hemolytic anaemia, the Coombs test is negative. The test is positive if antibodies (proteins) are destroying your red blood cells.
AKI due to thrombosis of the glomerular capillaries Neurological symptoms (headache, palsies, seizures)
Coagulation
Consumptive causes:
Haemolytic uraemic syndrome (HUS):
- What is the triad for the features seen on bloods?
- What sort of symptoms do they have? - think generally for illness
Low platelets
Low RBC’s
AKI due to thrombosis of the glomerular capillaries
Initial symptoms typically include bloody diarrhoea, fever, vomiting, and weakness. Kidney problems and low platelets then occur as the diarrhoea is improving.
Immune causes:
Immune thrombocytopenic purpura (ITP):
- What is the mechanism?
- What does happen after in children?
- Megakaryocytes are raised in the marrow. Why?
- Why are platelet transfusions not recommended?
- How is it usually diagnosed?
Treatment:
- What drug is given first?
- What drug can be given to reduce bleeding? - also given in menorrhagia
What autoimmune diseases could cause this?
Viral infection such as Hep B and C can cause this. Why?
A diagnosis of exclusion
Antiplatelet autoantibodies
Post-infection - usually 2 wks
Megakaryocytes are cells in the bone marrow responsible for making platelets,
They are quickly destroyed by the autoantibodies
Corticosteroids - THIS IS THE FIRST LINE FOR ALL THROMBOCYTOPENIA’S
Tranexamic acid
------ SLE RA HIV ------ Decreased production of hormone thrombopoietin (TPO) in the damaged liver ===
Immune causes:
Why do NSAIDs affect platelets?
How does heparin cause heparin-induced thrombocytopenia?
Aspirin and nonaspirin nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit platelet cyclooxygenase, thereby blocking the formation of thromboxane A2. These drugs produce a systemic bleeding tendency by impairing thromboxane-dependent platelet aggregation and consequently prolonging the bleeding time.
Heparin-induced thrombocytopenia (HIT) is caused by antibodies that bind to complexes of heparin and platelet factor 4 (PF4), activating the platelets and promoting a prothrombotic state.
Dilutional causes:
What type of Rx could dilute the blood to the point where the platelet count drops for the blood volume?
What physiological state may lead to low platelets due to hypervolaemia?
Massive transfusion
Pregnancy - WOMAN
Investigations:
Blood films are usually first line - what does clumping mean?
What bloods should be done and why? - 5
This is when the platelets clump together giving the illusion that the platelet count is low when it actual fact, they are bunched together at a high concentration
B12/folate - cause
LFT’s - Liver disease
U&E - just check
Clotting - DIC
What are some S+S of thrombocytopenia?
Bleeding:
- nose bleeds
- gym bleeding
- oral blood blisters
- menorrhagia
- bruises
- petechiae
Thrombocytosis:
What’s another way of saying thrombocytosis?
What is it?
Most patients asymptomatic; some may have migraine, dizziness, pruritus, or tinnitus.
What typically triggers thrombocytosis?
What 2 myeloproliferative diseases cause this?
What organ if not working properly, could cause this?
Treatment:
- What drug is used to thin the blood?
- What drug can also be added to reduce the risks of clots?
Spleen - hyposplenism
Thrombocythaemia
High levels of platelets
Infection, Inflammation and post - op - check clinical picture and check previous results:
- Check bloods a few days after to double check
- if unclear, a blood film can be done
Essential thrombocytosis/thrombocythaemia
Polycythaemia vera
Aspirin
Hydroxycarbamide
