Smartpance Hematology Flashcards
What is autoimmune hemolytic anemia (AIHA)?
Autoimmune hemolytic anemia is an extrinsic
type of hemolytic anemia because the immune
system mistakenly believes our own red blood
cells are foreign, or non-self, structures, so it
secretes antibodies against proteins found on
the RBC membrane.
Based on the type of antibodies produced, autoimmune hemolytic anemia
can be divided into what
two classifications?
Based on the type of antibodies produced,
autoimmune hemolytic anemia can be divided
further into IgG, also called warm antibody,
hemolytic anemia, and IgM hemolytic anemia,
also called cold agglutinin disease.
Warm Autoimmune Hemolytic Anemia (WAIHA)?
Warm is the more common type and is almost
always due to IgG antibodies. It’s when hemolysis occurs at temperatures greater than
or equal to core human body temperature of
37º celsius. The main red blood cell antigen
that reacts with these IgG antibodies is the Rh
antigen.
Cold Autoimmune Hemolytic Anemia (CAIHA)?
Cold autoimmune hemolytic anemia is much
rarer, and it occurs when people’s blood is
exposed to cold temperatures, usually in the
range of 0º to 10º celsius - like when a person
goes out into cold weather during winter. With
cold autoimmune hemolytic anemia, the culprits are IgM-type antibodies, and the primary
red blood cell antigens are termed L, I, and P.
Is autoimmune hemolytic
anemia microcytic, normocytic, or macrocytic?
Since these red blood cells are normal in
size, approximately 80-100 fL, autoimmune
hemolytic anemia is considered normocytic.
How are the LDH levels
in someone with hemolytic
anemia?
With intravascular hemolysis, when RBCs are
broken down, an intracellular enzyme called
lactate dehydrogenase, or LDH, spills out directly into the plasma, so LDH plasma levels
increase
How are the Bilirubin levels
in someone with hemolytic
anemia?
Hemoglobin spills out of the RBC and some
of this hemoglobin breaks up into heme and
globin.
Heme is converted into unconjugated, or indirect, bilirubin which is then taken up by the
liver cells and eventually secreted out with bile.
Some of the bilirubin is converted to urobilin
which is what gives urine that yellow color, but
if there’s too much of it, the urine becomes a
much darker color, like black tea.
Causes of warm autoimmune hemolytic anemia?
In children, viral infections are a common precipitant. Other causes include systemic lupus
erythematosus, lymphomas, and leukemia, to
name a few, as well as some drugs such
as beta-lactam antibiotics like penicillin and
cephalosporins.
Causes of cold autoimmune hemolytic anemia?
Cold autoimmune hemolytic anemia, on the
other hand, has different causes depending
on presentation. With chronic disease, causes
also include leukemia and lymphomas, while
acute forms are more often caused by infections like viral pneumonia, mycoplasma, and
infectious mononucleosis.
Autoimmune hemolytic
anemia usually progresses
slowly, over days to weeks,
but sometimes hemolysis
occurs at a rapid rate, over
the course of hours, which is called ?
Hemolytic crisis
Treatment of warm autoimmune hemolytic anemia and cold autoimmune
hemolytic anemia?
corticosteroids for warm
autoimmune hemolytic anemia and plasmapheresis for cold autoimmune hemolytic anemia
A 37-year-old female presents with pale mucous
membranes, epistaxis, and
scattered petechiae on her
arms, legs, and torso that
do not blanch to palpation/pressure. Laboratory
findings note a hemoglobin, hematocrit, and white
count in the normal range.
Platelet count is <30,000.
What is the likely diagnosis?
Idiopathic thrombocytopenic purpura
What is idiopathic
thrombocytopenic purpura
(ITP)?
Autoantibodies are directed against platelet
surface antigens, leading to premature platelet
destruction.
What are the signs and
symptoms of idiopathic
thrombocytopenic purpura
(ITP)?
Symptoms of thrombocytopenia which include
may include easy bruising, mucosal bleeding,
purpura, and petechial rashes. Some patients
complain of a viral syndrome several weeks
before the onset.
What are purpura?
A rash of purple spots due to small blood
vessels leaking blood into the skin, joints, intestines, or organs.
Petechiae vs purpura?
The main difference in appearance between
petechiae and purpura is their size:
*Petechiae are very small, less than 4 millimeters (mm) in size.
*Purpura are larger areas of bleeding under the
skin, typically between 4 mm and 10 mm.
*Areas that are larger than 10 mm are referred
to as ecchymosis.
How is the diagnosis of idiopathic thrombocytopenic
purpura (ITP) made?
ITP is a diagnosis of exclusion, so no specific
test confirms the diagnosis. The CBC usually
shows isolated thrombocytopenia, with a normal hematocrit and leukocyte count, normal
kidney function, normal RBC morphology on
peripheral smear, and normal PT/aPTT
What would a bone marrow
aspirate or biopsy show in
an ITP patient?
Normal to increased megakaryocytes
What diseases are associated with ITP?
Chronic lymphocytic leukemia, Hodgkin disease, non-Hodgkin lymphoma, SLE, rheumatoid arthritis, and HIV infection
Should all patients with ITP
receive treatment?
No, only if there is significant bleeding or a
platelet count <30 × 109/L. Occasionally, the
disease spontaneously regresses, especially
in childhood.
What clinical intervention
would be the best option for a patient who is
diagnosed with ITP whose platelet count averages 55,000 over 3 to 4
months?
Observation in patients with no active or regular signs of bleeding and counts that remain above 50,000, observation is the best
approach.
Do platelet transfusions increase the platelet count in
ITP?
No, but if severe uncontrollable bleeding occurs, then platelet transfusion is indicated.
What is the mainstay of initial treatment of severe ITP
in adults without bleeding?
Corticosteroids
What are other treatment
options for ITP if corticosteroids fail?
IV Ig, anti-Rho(D) Ig (in Rh-positive patients only), thrombopoietin receptor agonists, and
rituximab
