Platelet Disorders

Question 1

Most common cause of bleeding

Answer 1

Thrombocytopenia

Question 2

T/F: pts with thrombocytosis are usually asymptomatic

Answer 2

True

Question 3

Pts with _____ _____ (a myeloproliferative d/o) may have bleeding, thrombosis, or both as a component of their presentation

Answer 3

Essential thrombocythemia

Question 4

Complication due to vasomotor changes that occurs with essential thrombocythemia characterized by burning pain and responds to aspirin therapy

Answer 4

Erythromelalgia

Question 5

4 drugs/drug classes that are known for lowering the platelet count

Answer 5

Loop diuretics
H2 blockers
Digoxin
Abx

Question 6

process involved in pseudothrombocytopenia and the characteristic finding on peripheral smear

Answer 6

Pseudothrombocytopenia is an in vitro sampling error resulting from CBC drawn in EDTA tube

Characteristic finding is in vitro clumping

Question 7

What is the plan for additional evaluation of a measured platelet count in pseudothrombocytopenia?

Answer 7

Repeat CBC in heparin or citrate tube

Question 8

4 disorders that affect platelet production

Answer 8

B12 or folate deficiency — associated with pancytopenia, macrocytosis, macro-ovalocytes, hypersegmented neutrophils, and possible neuro sxs

Bone marrow disorder (acute leukemia, aplastic anemia, myelodysplastic syndrome)

Toxin or drug-mediated bone marrow injury

Infection (HIV, Hep B and C, EBV, rubella, DIC, other infections)

Question 9

Describe workup for pt with thrombocytopenia in which platelet count is <100,000/microliter

Answer 9

Exclude pseudothrombocytopenia on PB smear

Abnormal blood smear or abnormality of WBC or RBC suggests bone marrow d/o

Large spleen suggests hypersplenism

Immune mediated; primary or secondary ITP; drug-induced

Question 10

Describe workup for pt with thrombocytopenia in which platelet count is >100,000/microliter

Answer 10

Exclude pseudothrombocytopenia on PB smear

Follow CBC — if stable, just continue to observe

Question 11

Management for thrombocytopenia in aplastic anemia

Answer 11

Tx aplastic anemia w/ allogeneic HCT in pts <40 that are otherwise healthy with HLA-compatible sibling

Pts not eligible for above can get immunosuppressives with antithymocyte globulin and cyclosporin

Question 12

Tx for thrombocytopenia due to marrow invasion

Answer 12

Treat if symptomatic

Supportive care = red cell and/or platelet transfusion

Low intensity therapy = hematopoietic growth factors, immunosuppressives, lenalidomide

High intensity therapy = chemo with allogeneic HCT

Question 13

How does hypersplenism lead to platelet sequestration

Answer 13

Cytopenias result from increased destruction of cell elements secondary to reduced flow of blood through enlarged and congested cords or to immune-mediated mechanisms

Question 14

How does ITP result in platelet destruction?

Answer 14

Autoantibodies — arise in 3 settings — response to a drug (quinine), association with a disease (HIV, SLE, H.pylori, etc), or idiopathic

Question 15

Consumptive thrombocytopenia and microangiopathic hemolysis from platelet thrombi that form throughout microvasculature

Presents with fever, AKI, and fluctuating neuro signs

Answer 15

TTP-HUS

Question 16

Lab findings in TTP-HUS

Answer 16

Prominent schistocytes, decreased haptoglobin, elevated LDH, check for ADAMSTS13

Question 17

Management of ITP

Answer 17

Glucocorticoids +IVIG

[consider immunosuppressives — anti-Rho Ig, rituximab]

Question 18

HIT management

Answer 18

Discontinue heparin, replace with rapidly acting AC (lepirudin, argabotran)

Question 19

TTP/HUS management

Answer 19

Plasma exchange transfusion and glucocorticoids; can consider rituximab

[in young pts with HUS d/t O157H7 just do supportive care — better px]

Question 20

Disorders that result in secondary thrombocytosis

Answer 20

Acute blood loss
Iron deficiency
Asplenic states
Recovery from thrombocytopenia
Malignancy
Chronic inflamm/infectious dz
Acute inflamm/infectious dz
Response to exercise
Response to drugs (vincristine, epinephrine, ATRA, cytokines, growth factors)

Question 21

Meds that affect platelet function

Answer 21

ASA
NSAIDs
Dipyradimole
Clopidogrel
Ticlopidine
Ticagrelor
Abciximab
Eptifibitide
Nitrates
Ca channel blockers
Heparin

Question 22

List inherited d/o of platelet function

Answer 22

Bernard Soulier
Gray platelet syndrome
VW disease
Wiskott aldrich
Chediak hegashi
Hermansky pudlak
Glanzmann thrombasthenia

Question 23

Defect in gray platelet syndrome

Answer 23

Defect is in platelet alpha granules

Question 24

Defect in glanzmann thrombasthenia

Answer 24

Defect is in GPIIB/IIIA

Question 25

List d/o and clinical situations that influence platelet function

Answer 25

``` Liver dz Cardiopulmonary bypass Uremia Dysproteinemia Myeloproliferative d/o DM Trauma Acquired glanzmann thrombasthenia ```

Question 26

The diagnosis of essential thrombocythemia is based on persistent platelet count >600,000 in the absence of a secondary cause. Occasionally the count is sufficiently high (>1,000,000) that a secondary cause may be excluded. Approximately 1/2 of ET pts have ___ mutation

Answer 26

JAK2 [make sure Philadelphia chr is negative and pt does not have concomitant erythrocytosis to r/o CML and PRV]

Question 27

Tx plan for essential thrombocythemia

Answer 27

In pts <60 with no prior thromboembolic event and a platelet count <1000000, just observe Higher risk pts are treated with myelosuppressive hydroxyurea + low dose ASA (can add IFN-a or anagrelide if needed)

Question 28

17 y/o male with easy bruisability and petechial rash on his legs; he reports a cold 1 month ago. He most likely has ``` A. Drug-related rash B. ITP C. DIC D. TTP E. IDK ```

Answer 28

B. ITP

Question 29

17 y/o male with easy bruisability and petechial rash on his legs; he reports a cold 1 month ago. He most likely has ITP. Platelet count is probably close to ``` A. 140,000 B. 357,000 C. 75,000 D. 30,000 E. 600,000 ```

Answer 29

D. 30,000

Question 30

17 y/o male with easy bruisability and petechial rash on his legs; he reports a cold 1 month ago. He most likely has ITP. Platelet count is 41,000. He should be tx with ``` A. IVIG B. Prednisone C. Rituximab D. Observation E. Romiplostim ```

Answer 30

D. Observation Usually don’t treat unless count is <30,000. Follow 1-2x/week to repeat platelet counts and make sure it is improving

Question 31

65 y/o man with DVT is put on enoxaparin and warfarin in the hospital. He has no other medical problems and is not taking any other medications. The platelet count on first hospital day is 175,000, but drops to 80,000 on hospital day 5, at which time physical exam is normal. Other than thrombocytopenia his CBC and CMP are normal. INR is 1.5 and aPTT is in therapeutic range. With the exception of decreased platelet numbers, the PB smear is normal. The pt most likely has ``` A. ITP B. DIC C. TTP D. HIT E. Pseudothrombocytopenia ```

Answer 31

E. HIT [enoxaparin is LMWH]

Question 32

65 y/o man with DVT is put on enoxaparin and warfarin in the hospital. He has no other medical problems and is not taking any other medications. The platelet count on first hospital day is 175,000, but drops to 80,000 on hospital day 5, at which time physical exam is normal. Other than thrombocytopenia his CBC and CMP are normal. INR is 1.5 and aPTT is in therapeutic range. With the exception of decreased platelet numbers, the PB smear is normal. He is dx with HIT. He should be managed with A. Plasmapheresis B. Discontinuing current meds and initiate argatroban C. Repeat labs in heparin or citrate tubes D. Discontinue enoxaparin only E. IVIG

Answer 32

D. Discontinue enoxaparin only Want to keep him on warfarin, bc he is in therapeutic range with his INR

Question 33

19 y/o F with 1 wk hx of 103 fever, arthralgias, myalgias; no clear febrile focus. Her spleen tip is palpable on deep inspiration. Labs demonstrate WBC 1.9 with 37% segs, 8% bands, 40% lymphs, 12% monos, 2% eos, 1% basos; Hb/Hct 11.2/35; plts 865K. Her findings most likely suggest ``` A. Acute bacterial illness B. Acute viral illness C. Acute leukemia D. An indolent NHL E. Parasitic infection ```

Answer 33

B. Acute viral illness

Question 34

19 y/o F with 1 wk hx of 103 fever, arthralgias, myalgias; no clear febrile focus. Her spleen tip is palpable on deep inspiration. Labs demonstrate WBC 1.9 with 37% segs, 8% bands, 40% lymphs, 12% monos, 2% eos, 1% basos; Hb/Hct 11.2/35; plts 865K. Her findings most likely suggest a viral illness (reactive process). Her thrombocytosis is best managed by ``` A. Splenectomy B. Anagrelide C. Oral ferrous sulfate D. Observation E. Hydroxyurea ```

Answer 34

D. Observation Probably will improve in 7-10 days

Question 35

55 y/o man with diplopia, HA, sore fingers and hand that appears red which you diagnose as erythromelalgia. CBC shows WBC 9.9 with 75% segs, 23% lymphs, 2% monos; Hb 15.1/Hct47; plts 1.2 M. The pt most likely has ``` A. Cellulitis B. Angiosarcoma C. RA D. Essential thrombocythemia E. Toxic epidermal necrolysis ```

Answer 35

D. Essential thrombocythemia

Question 36

55 y/o man with diplopia, HA, sore fingers and hand that appears red which you diagnose as erythromelalgia. CBC shows WBC 9.9 with 75% segs, 23% lymphs, 2% monos; Hb 15.1/Hct47; plts 1.2 M. The pt most likely has ET. How would this be treated? ``` A. Cephalexin B. Baby aspirin daily C. Cytotoxic chemo D. Debridement and skin graft E. MTX ```

Answer 36

B. Baby aspirin daily

Question 37

66 y/o woman evaluated in hospital for abnormal bleeding. She was admitted yesterday for UTI and bacteremia. She has no other medical problems and is not on any additional medications. On PE, temp is 102.6, BP 85/60, pulse is 115/min and RR is 18/min. Bleeding is noted on mucous membranes around IV access sites. Multiple ecchymoses are present on arms and legs. Labs show Hb 8.5, plts 35,000; PT 15 sec, aPTT 30 sec, D-dimer elevated, fibrinogen decreased. Peripheral smear shows schistocytes. This pt most likely has: ``` A. ITP B. DIC C. TTP D. HIT E. Pseudothrombocytopenia ```

Answer 37

C. TTP