Hemolytic Anemias Flashcards
What are some possible defects that may lead to hereditary spherocytosis?
Defects in ankyrin (50%), band 3 (15%), band 4.2 or alpha/beta-spectrin –> weakened or absent spectrin causing a weakened RBC cytoskeleton
What test differentiates hereditary spherocytosis from autoimmune hemolytic anemia?
DAT will be negative in hereditary spherocytosis
What virus could cause aplastic crisis in individuals with hereditary spherocytosis?
Parvovirus B19
How is G6PDH deficiency passed on?
X-linked
What happens in G6PDH deficiency?
RBC’s cannot reduce oxidant stress and accumulate denatured, precipitated Hb (Heinz bodies) that damage the cell membrane and cause lysis (intravascular) or are removed by the spleen (extravascular hemolysis)
What is cell is characteristic of G6PDH deficiency?
Bit cells
What are some oxidant stressors that could lead to an acute development of G6PDH symptoms?
Fava beans
Infection
Drugs – dapsone, sulfonamides, primaquine, nitrofurantoin, quinolones
What is the pathophysiology of paroxysmal nocturnal hemoglobinuria (PNH)?
Stem cell with deficiency in GPI-linked proteins – including the anti-complement proteins CD55 and CD59 on RBCs and WBCs
Makes RBCs (and WBCs to a lesser extent) subject to complement mediated lysis
What are some clinical features of PNH?
Hypercoagulability (thrombi at unusual sites)
Accentuation of lysis at night
RBC autoantibodies that react at 37 degrees causing intravascular coating of RBCs and extravascular lysis in the spleen
Warm autoimmune hemolytic anemia
What test is used to determine if an autoimmune hemolytic anemia is present?
Direct antiglobulin test (DAT)
What types of disease can be associated with warm AIHA??
B-cell lymphoproliferative disorders
RBC IgM autoantibodies that react at <30 degrees and may lead to extravascular hemolysis in the spleen and liver
Cold autoimmune hemolytic anemia
How does acute cold AIHA differ from chronic cold AIHA?
Acute is usually 2-3 weeks post-infection
Chronic is usually accompanied by a lymphoproliferative disorder
What are some unique clinical features of cold AIHA?
Raynaud phenomenon (obstructive symptoms) Associated with mycoplasma infections and EBV infections
Traumatic shearing and subsequent lysis of RBCs d/t blood flow abnormality
Microangiopathic hemolytic anemia
What are some things that can lead to the shearing seen in microangiopathic hemolytic anemia?
Malfunctioning heart valve
Vascular obstructions by microthrombi
What is seen on smear review in microangiopathic hemolytic anemia?
Schistocytes
What are some states that microangiopathic hemolytic anemia may be associated with?
DIC
TTP
Metastatic cancer
Malignant hypertension
How does malaria/babesia lead to a hemolytic anemia?
Intracellular parasites that infect RBCs and cause lysis as they propagate
At <20% hemolysis what is the Hgb expected to be and what are some signs and symptoms?
> 11 g/dL
Restlessness
At 20-30% hemolysis what is the Hgb expected to be and what are some signs and symptoms?
10-11 g/dL
Anxiety, dyspnea with exertion
Orthostatic hypotension; tachycardia with exertion
At 30-40% hemolysis what is the Hgb expected to be and what are some signs and symptoms?
8-9 g/dL
Syncope
Orthostatic hypotension; tachycardia at rest
At <40% hemolysis what is the Hgb expected to be and what are some signs and symptoms?
<8
Confusion
Shock
What are some rare complications of hemolytic anemia?
Pigment induced kidney injury
Folate deficiency d/t increased utilization
Increased risk of venous and arterial thrombosis, including venous thrombosis of atypical sites (portal vein, cerebral venous sinus)
What are some clinical features of hemolytic anemia related to the underlying disease process?
Splenomegaly, hepatomegaly – from extra-medullary hematopoiesis (thalassemia, PK deficiency, hereditary spherocytosis)
Skeletal changes – from expansion of marrow, chipmunk facies, convex bones (beta thalassemia major)
Asplenia – sickle cell
Microangiopathic hemolytic anemia
