Immune Mediated Hemolytic Anemia Flashcards
T/F: immune mediated hemolytic anemia can be primary or secondary
True
Immune mediated hemolytic anemia is a type ________ hypersensitivity reaction
2
Anti-RBC antibodies formed against RBCs
Breeds associated with IMHA?
American Cocker Spaniels
English cocker Spaniels
English springer Spaniels
Cross breeds English sheepdogs Irish setters Collies Dachshunds Labrador retrievers Min schauzers
Signalment of IMHA?
Female > male
Mean age 6 years
Clinical signs associated with IMHA?
Collapse, weakness, lethargy, exercise intolerance
Anorexia, dyspnea, vomiting, and diarrhea
Fever, lymphadenopathy
PU/PD
Tissue hypoxia —> tachypnea, tachycardia and increased CO
Splenomegaly and hepatomegaly
Icterus
Pigmenturia
What is the syndrome called when there is IMHA and IHT?
Evans syndrome
What other immune mediated diseases can accompany IMHA?
Thrombocytopenia
Systemic lupus erythematosus
Glomerulonephritis
Polyarthritis
What are the most common antibody types in IMHA reactions?
IgM and IgG
The antibodies target _________ on the RBC in IMHA
Glycophorin
Attachment of the antibody to the RBC can cause.. ??
Extravascular hemolysis (IgG) —> splenomegaly and hepatomegaly
Intravascular hemolysis (IgM) —> hemoglobinemia and hemoglobinuria
Intravascular RBC agglutination
Pathogenesis of leading to intravascular hemolysis?
IgM attaches to RBC
Complement system activated —> membrane attack complex forms and damages cell membrane
-> hemoglobinemia and hemoglobinuria
Pathogenesis of extravascular hemolysis
IgG attaches to RBC
Removal of the affected cell my macrophage-phagocyte system (in liver and spleen)
DDX for canine IMHA?
Primary/ idiopathic (50-70%)
Secondary
- infection dz
- neoplasia
- drug
- autoimmune
Autoimmune hemolytic anemia - incompatible blood transfusions
DDX for feline IMHA?
Primary/idiopathic (35%)
Secondary
- infection
- neoplasia
Autoimmune hemolytic anemia
-feline neonatal isoerythrolysis (eg type A or AB kitten consumes colostrum from type B cat)
When you have IMHA what will you include in your diagnostics to rule out secondary causes?
3view thoracic rads Abdominal US Heartworm antigen test PCR - infectious dz Fecal exam - hookworm
What would you see on a blood smear that would be consistent with IMHA?
Spherocytosis
Recticulocytes
Polychromatic
Anisocytosis
Evidence of parasite
Increased number of normoblast (nucleated RBC)
Left shift neutrophilia
How can you determine if agglutination is due to IMHA or if its just clumping?
Saline agglutination test—> 1drop of blood to 10 drops saline
Coombs test (direct agglutination test) —> looks for autoantibodies against RBC
What is the osmotic fragility test?
Take blood sample, centrifuge RBC
Take 5 drops of RBC into two tubes
Tube 1 —> add 5ml 0.9% saline
Tube 2 —> add 5ml 0.55% saline
If tube 2 is red after 5 min you have membrane fragility
85-100% of dogs with IMHA are postive OFT
What will you see in biochem and UA with IMHA?
Biochem - hyperbilibrubinemia
UA
- bilirubinuria
- hemoglobinuria
IMHA will cause what changes with thromboelastography?
Lower median clot formation time
Higher median angle
Higher max amplitude
Higher median clot strength
=> hyper-coagulable
Why do bone marrow cytology with IMHA?
Evaluate for evidence of myeloid dysplasia
Usually have erythroid proliferation
Occasionally chronic cases could get myeloid fibrosis
Severe hypoxia can damage bone marrow
What evidence would point to hypercoagulabilty in an IMHA ?
Hyperfibronogenemia
Antithrombin deficiency
Increased FDPs
Thromboelastography
IMHA treatment
Packed RBC
Crystalloid or colloid or both
Immunosuppression - pred is best can have azathioprine
How many ml of packed RBC do you want to give to your 18kg canine IMHA patient with a PCV of 12%
Amount (ml) = (PCVreq - PCVpaitent) / PCVblood x body weight x k
K in dogs = 90
PCV of packed PBC = 7%
PCVreq = usually want to bring patient up to 20% PCV
(20-12)/70 x 18kg x 90 = 300mL
