Thrombocytopenia

Question 1

formation of the platelet plug will be impaired if there is:

Answer 1

not enough platelets or if the platelets do not work properly. Thrombocytopenia (too few platelets) is one of the most common reasons why patients bleed too much.

Question 2

clinical features associated with thrombocytopenia

Answer 2

bleeding from mucocutaneous surfaces

• prolonged bleeding after trauma/ procedures.
• petechial rash due to increased hydrostatic pressure.

Question 3

platelet threshold for daily activity and surgery

Answer 3

> 30 for Dailey activity, and >50 for minor surgery

Question 4

how to confirm thrombocytopenia

Answer 4

CBC
PBS: evaluate morphology or platelet appearance:
- could have pseudothrombocytopenia (platelets clumping so looking like there’s less) due to platelet agglutination in the presence of EDTA.

Question 5

overall DDX for thrombocytopenia (three categories)

Answer 5

1. decreased platelet production
2. increased platelet destruction
3. sequestration

Question 6

why might thrombocytopenia occur due to decreased production

Answer 6

• bone marrow damage due to megakaryocytic abnormalities
• acquired causes could include drug toxicity, chemical exposure, viral infection, infiltration of the bone marrow by cancer, vitamin b12 or folate deficiency

Question 7

why might thrombocytopenia occur due to platelet destruction

Answer 7

• immune mediated caused by anti platelet antibodies (could be also or autoimmune)
• non-immune causes due to platelet consumption – DIC, TTP, HUS, HELLP

Question 8

how to diagnose ITP (immune thrombocytopenic purport)

Answer 8

• caused by a production of autoantibodies which result in clearance of antibody bound platelets from circulation and associated with impaired platelet production.
• diagnosis made by excluding other cause of thrombocytopenia and the OTHER BLOOD COUNTS ARE NORMAL

Question 9

someone presence with bleeding problems like bruising.he does not do drugs, and his stats are good enough to rule out DIC, TTP, HUS, and HELLP (not pregnant). His platelets are super low, but his MCV, WBC are all normal. Possible dx?

Answer 9

after ruling out HIT, splenomegaly/sequestration, and bone marrow problems/production problems, since his platelets are low but other blood counts are normal, it could be ITP (immune mediated platelet destruction)

Question 10

Tx for Itp

Answer 10

• prevent bleeding if platelets are <30
• first line therapy consists of corticosteroids
• intravenous immunoglobulins impair the cleanse of antibody bound platelets by the RES and should be used in pattens with bleeding symptoms or in those who need a quick increase in platelet count
• platelet transfusions are resaved for its with significant or life-threatening bleeding

Question 11

what is HIT? Clinical presentation?

Answer 11

heparin-induced thrombocytopenia. considered to be immune mediate platelet destruction via drug induced immune mediated thrombocytpoenita.

• life threatening. complication os expire to unfractionated or LMW heparin.
• thrombocytopenia occurs because antibody bound platelets are removed by the RES and platelets are consumed during the production of thrombosis.

In HIT, the immune system forms antibodies against heparin when it is bound to a protein called platelet factor 4 (PF4).
The IgG antibodies form a complex with heparin and PF4 in the bloodstream. The tail of the antibody then binds to the FcγIIa receptor, a protein on the surface of the platelet. This results in platelet activation and the formation of platelet microparticles, which initiate the formation of blood clots; the platelet count falls as a result, leading to thrombocytopenia

Thrombocytopenia happens in HIT because antibody-bound platelets are removed by RES. Platelets are consumed in the blood clots too.
- clinical features include new onset thrombocytpp[enia in a pt exposed to heparin, a platelet could drop >50% from baseline, new venous or arterial thrombosis, necrotic skin lesions at sites of heparin injection.

Question 12

treatment for Hit:

Answer 12

• immediate discontinuation of heaprain

- administration of non-heparin anticoagulant.

Question 13

platelet production problems can be caused by decreased megakaryopoiesis, or ineffective megakaryopoiesis. give examples of both

Answer 13

decreased:

• aplastic anemia
• toxic damage via chemotherapy
• displacement of good marrow by abnormal elements like leukaemia or tumors

ineffective:

• nutritional megaloblastic anemia (vitamin b12 or folate)
• folate antagonists
• congenital thrombocytopenia.

Question 14

platelet destruction could cause thrombocytopenia. this could be due to immune (allo and auto) and non immune causes. give examples

Answer 14

alloimmune: PTP: post transfusion purpura
autoimmune: ITP (only affects platelets, other blood cells are normal)
non immune: drug induced HIT, DIC, sepsis, HUS, TTP, HELLP

Question 15

treatment for ITP

Answer 15

treatment when platelets are below 30, consider using steroids. do not give plasma/IVIG/splenectomy/immunosuppressants/thrombopoietin mimetic) unless actively bleeding or concomitant bleeding risk conditions like surgery or hemophilia. .

Question 16

why does splenomegaly cause thrombocytopenia

Answer 16

when spleen enlarges, thrombocytes get trapped and cannot circulate in the blood. splenomegaly can be caused by infection, inflammation, congestion (portal hypertension pushing portal veins out, blood flows back towards spleen), malignancy, red cell disorders, storage disease.