Platelet Disorders Flashcards
Most common cause of bleeding
Thrombocytopenia
T/F: pts with thrombocytosis are usually asymptomatic
True
Pts with _____ _____ (a myeloproliferative d/o) may have bleeding, thrombosis, or both as a component of their presentation
Essential thrombocythemia
Complication due to vasomotor changes that occurs with essential thrombocythemia characterized by burning pain and responds to aspirin therapy
Erythromelalgia
4 drugs/drug classes that are known for lowering the platelet count
Loop diuretics
H2 blockers
Digoxin
Abx
process involved in pseudothrombocytopenia and the characteristic finding on peripheral smear
Pseudothrombocytopenia is an in vitro sampling error resulting from CBC drawn in EDTA tube
Characteristic finding is in vitro clumping
What is the plan for additional evaluation of a measured platelet count in pseudothrombocytopenia?
Repeat CBC in heparin or citrate tube
4 disorders that affect platelet production
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)
Describe workup for pt with thrombocytopenia in which platelet count is <100,000/microliter
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
Describe workup for pt with thrombocytopenia in which platelet count is >100,000/microliter
Exclude pseudothrombocytopenia on PB smear
Follow CBC — if stable, just continue to observe
Management for thrombocytopenia in aplastic anemia
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
Tx for thrombocytopenia due to marrow invasion
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
How does hypersplenism lead to platelet sequestration
Cytopenias result from increased destruction of cell elements secondary to reduced flow of blood through enlarged and congested cords or to immune-mediated mechanisms
How does ITP result in platelet destruction?
Autoantibodies — arise in 3 settings — response to a drug (quinine), association with a disease (HIV, SLE, H.pylori, etc), or idiopathic
Consumptive thrombocytopenia and microangiopathic hemolysis from platelet thrombi that form throughout microvasculature
Presents with fever, AKI, and fluctuating neuro signs
TTP-HUS
Lab findings in TTP-HUS
Prominent schistocytes, decreased haptoglobin, elevated LDH, check for ADAMSTS13
Management of ITP
Glucocorticoids +IVIG
[consider immunosuppressives — anti-Rho Ig, rituximab]
HIT management
Discontinue heparin, replace with rapidly acting AC (lepirudin, argabotran)
TTP/HUS management
Plasma exchange transfusion and glucocorticoids; can consider rituximab
[in young pts with HUS d/t O157H7 just do supportive care — better px]
Disorders that result in secondary thrombocytosis
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)
Meds that affect platelet function
ASA NSAIDs Dipyradimole Clopidogrel Ticlopidine Ticagrelor Abciximab Eptifibitide Nitrates Ca channel blockers Heparin
List inherited d/o of platelet function
Bernard Soulier Gray platelet syndrome VW disease Wiskott aldrich Chediak hegashi Hermansky pudlak Glanzmann thrombasthenia
Defect in gray platelet syndrome
Defect is in platelet alpha granules
Defect in glanzmann thrombasthenia
Defect is in GPIIB/IIIA
List d/o and clinical situations that influence platelet function
Liver dz Cardiopulmonary bypass Uremia Dysproteinemia Myeloproliferative d/o DM Trauma Acquired glanzmann thrombasthenia
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
JAK2
[make sure Philadelphia chr is negative and pt does not have concomitant erythrocytosis to r/o CML and PRV]
Tx plan for essential thrombocythemia
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)
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
B. ITP
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
D. 30,000
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
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
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
E. HIT
[enoxaparin is LMWH]
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
D. Discontinue enoxaparin only
Want to keep him on warfarin, bc he is in therapeutic range with his INR
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
B. Acute viral illness
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
D. Observation
Probably will improve in 7-10 days
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
D. Essential thrombocythemia
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
B. Baby aspirin daily
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
C. TTP
