Thrombocytopenia Flashcards
what are thrombocytes
small disked shaped cell fragments without a nucleus. They are produced in the marrow and derived from megakaryocytes.
-they are involved in clotting
what is the average life span of thrombocytes in peripheral blood under normal circumstances?
7days
where are reserved platelets stored?
in the spleen and it is released when it is needed
where are platelets destroyed?
in the spleen
what is the normal range for platelets?
150,000-300,000
what is the causes of thrombocytopenia if its not associated with anemia or leukopenia
accelerated platelet destruction
What does MINI stand for?
things that can cause thrombocytopenia M-metabolic I-Infectious N-Neoplastic I-Inflammatory/Immune
what things that are metabolic that will causes thrombocytopenia
drugs:heparin, penicillins, sulfas, anticonvulsants, Quinine
-Thrombotic Throbocytopenic Purpura
Hemolytic Uremic Syndrome
Severe bleeding or Hypersplenism
what are the infectious things that will cause thrombocytopenia?
particularly HIV and other Viral infections
Sepsis
DIC
what are the Neoplastic things that will cause thrombocytopenia?
DIC
Myelophthisis
what are the inflammatory/Immune things that will causes Thrombocytopenia
ITP
What is heparin induced thrombocytopenia?
HIT
immune mediated by anti-heparin antibodies
Associated with diffuse inta-vascular thrombosis and end organ ischemia
This is urgent the heparin needs to be stopped as one considers this Dx
When does HIT occur and What classifies a platelet count as HIT?
occur after D#5 of treatment or at re-expososure
Platelets are usually 25,000-75,000
bleeding is rare
how is hit diagnosed
by ordering test for a heparin induced anti-platelet antibodie
What are the other drugs know for causing thrombocytopenia
Penicillins and Ceephalosporins
Sulfa drugs
Anticonvulsants
Quinine containing drugs or beverages
what is the only definitive Dx and Rx for thrombocytopenia?
withdrawal of the suspected medication
What creates thrombocytopenia
microthrombi forming in the small vessels consuming platelets and incuding a microangiopathic hemolytic anemia which cause RBC’s to be broken down as they pass through strands of fibrin
what are signs of thrombocytopenia
flucutuating neurological Sx Abnormal speech confusion jaundice purpura/petechiae
what is the pentad of Thrombotic thrombocytopenic purpura & hemolytic Uremic syndrome
Microangiopathic hemolytic anemia, Thrombocytopenia, renal failure, fluctuating neurologic signs and symptoms & fever
what is it called when renal failure dominates
Hemolytic Uremic syndrome
What are associated conditions
Viral infx, hemorrhagic diarrhea w.ecoli, pregnancy, clopidogrel, cyclosporin
what is the lab test for diagnosis of TTP
microangiopathic hemolytic anemia with thrombocytopenia
normal clotting studies
increase LDH (lactate dehydrogenae) indirect bilirubin, retic with a negative direct coombs test
decrease hatpoglobin
what is the Tx for TTP or HUS
Urgent plasmapharesis
If offending agent can be identified it should be withdrawn
Steriods may help
what needs to be done if renal failure is predominant
dialysis
What infectious etiologies cause thrombocytopenia
mononucleosis EBV
what is the treatment for infectious etiologies
supportive or steroids
how do you treat patient with HIV associated thrombocytopenia
should be treated with HAART (highly active anti retroviral therapy)
what is DIC
diffuse intravascular activation of the clotting system with associated mircoangiopathic hemolytic anemia and multi organ failure
what causes DIC
infections or cancers can activate the clotting system
Platelets are decreasing, soluble clotting factors are decreasing, but PT and PTT and fibrin split products are increasing
what is the Tx for DIC
Fresh frozen plasma
Heparin is rarely helpful
what are the two mechanism that cancer can cause thrombocytopenia
DIC, myelophthisis
what is myelophthisis
diffuse bone marrow infiltration crowds out the normal marrow
what is ITP
it is an auto immune condition with antibodies directed against several platelet associated surface antigens
The anti-bodies bind to platelets that leads to platelet destruction in the spleen
what is the epidemiology
children account for half of the new cases each year
childhood cases are usually self limiting
Adult cases are chronic
what is the presentation like with a patient who has a platelet count 20,000-100,000
may be asymptomatic and discovered fortuitously
may be associated with easy bruising or heavy menses
what is the presentation like with a patient who has a platelet count 5,000-20,000
spontaneous bruises and hematoma formation
mucoucutaneous bleeding
what is the presentation like with a patient who has a platelet count < 5,000
intracranial hemorrhages
GI bleeding
Spontaneous Organ bleeding
what is more important that absolute platelet count
patients clinical presentation
-does pt have wet purpura “blood blisters in the mouth or nose, nose bleeds, or GI bleeding or retinal hemorrhages
Wet purpura are a grave sign that requires urgent intervention
High dose steroids
IVIG
what are urgent clinical features that may prompt more urgent aggressive treatment
fever malnutrition advanced age extensive comorbidities inability to cooperate with outpatient therapy
what do lab results look like for ITP
other blood counts and hematopoietic cell lines are normal
Peripheral smear normal except sometimes with giant platelets and associate low platelet counts
normal bone marrow, though bone marrow evaluation rarely neede
how is ITP treated
guidelines recommend on treating in cases with platelets <30,000 or significant bleeding
main stay steroids
second line if refractory to steroids is IVIG, rituxumab, Anti-Rh-D
thrombopoietin receptor agnoists
last resort slpenectomy
when should platelet transfusion be used
should be reserved for cases with significant or life threatening bleeding
Allo-antibodies to transfused platelets invariably develop in patient who had multiple platelet transfusions
