Lecture 3 8/29/24 Flashcards
What are the characteristics of immune-mediated hemolytic anemia?
-autoantibodies are produced against patient’s own RBCs
-antibody binding to RBCs signals them to be phagocytized and broken down within macrophages
-antibody can potentially activate complement and cause RBC lysis in the bloodstream
Which type of hemolysis always occurs in IMHA?
extravascular
What laboratory changes can be present in a patient with IMHA?
-regenerative anemia
-spherocytes
-agglutination
-hyperbilirubinemia
-inflammatory leukogram
-hemoglobinemia
-hemoglobinuria
Which laboratory changes are specific for IMHA?
-spherocytes
-agglutination
What are the confirmatory tests for IMHA?
-saline dispersion test
-evaluation for RBC-bound antibodies
What are the characteristics of oxidant hemolytic anemia?
-RBCs are prone to oxidant injury due to carrying oxygen
-oxidant injury can lead to cellular damage or dysfunction if oxidant injury overwhelms antioxidant metabolic pathways
What are the possible manifestations of cellular damage/dysfunction caused by oxidative damage?
-methemoglobinemia
-heinz body formation
-eccentrocyte formation
What is the mechanism behind methemoglobin and the associated consequences?
mechanism: iron in hemoglobin is oxidized from Fe2+ to Fe3+
consequences: Fe3+ cannot bind oxygen, leading to poor oxygenation
What is the mechanism behind heinz bodies and the associated consequences?
mechanism: oxidation and precipitation of HGB globin proteins into pale pink inclusions
consequences: heinz bodies bind antibodies, promoting RBC death through extravascular hemolysis and resulting in anemia
What is the mechanism behind eccentrocytes and the associated consequences?
mechanism: oxidation of membrane components causing an area of membrane to adhere into a clear crescent
consequences: eccentrocytes have reduced deformability, promoting RBC death and resulting in anemia
What are the laboratory changes that can be seen with oxidant hemolytic anemia?
-pre-regenerative or regenerative anemia
-heinz bodies and/or eccentrocytes
-increased methemoglobin
-hyperbilirubinemia
-hemoglobinemia
-hemoglobinuria
Which pro-oxidants can cause oxidant hemolytic anemia upon ingestion?
-onions and garlic
-acetaminophen
-zinc
-wilted red maple
-copper
What is unique regarding cats and heinz bodies?
cats can have a few heinz bodies even in health
Which conditions can lead to the production of endogenous heinz bodies in cats?
-diabetic ketoacidosis
-lymphoma
-hyperthyroidism
Which RBC parasites commonly cause hemolytic anemia?
-Cytauxzoon felis
-hemotropic Mycoplasma spp.
-Anaplasma marginale
-Babesia spp.
Which mechanisms are possible in parasitic anemia?
-extravascular hemolysis
-intravascular hemolysis
-secondary IMHA
-anemia of inflammation
What are the laboratory changes that can be seen with parasitic anemia?
-pre-regenerative or regenerative anemia
-microscopic ID of RBC parasites
-hyperbilirubinemia
-hemoglobinemia
-hemoglobinuria
What are the two main mechanisms non-regenerative anemia?
-erythroid hypoplasia
-ineffective erythropoiesis
What are the characteristics of erythroid hypoplasia?
-decreased numbers of erythroid precursors in marrow
-indicates suppressed erythropoiesis
-occurs in disorders such as anemia of inflammation and anemia of CKD
What are the characteristics of ineffective erythropoiesis?
-intramedullary death of erythroid precursors
-marrow tries to produce RBCs but they die prior to maturation into reticulocytes
-occurs in disorders such as precursor-directed immune mediated anemia
What are the characteristics of anemia of inflammation?
-common cause of non-regenerative anemia
-can develop in any disease that leads to inflammatory cytokine release
What is iron sequestration?
component of anemia of inflammation mechanism in which inflammatory cytokines trap iron within its storage sites
What are the consequences of iron sequestration?
-total body iron stores are adequate, but decreased amounts are available for hemoglobin production
-causes a mild form of iron deficiency
What are the expected CBC results for a patient with anemia of inflammation?
-mild to moderate
-non-regenerative
-normocytic
-normochromic
-decreased CHr
What is the most common cause of a mild to moderate, normocytic, normochromic, non-regenerative anemia?
anemia of inflammation
What are the mechanisms for anemia of CKD?
-decreased renal production of erythropoietin, resulting in erythroid hypoplasia in marrow
-chronic GI bleeding, resulting in absolute iron deficiency
What are the expected CBC findings in a patient with anemia of CKD?
-mild to moderate
-normocytic
-normochromic
-non-regenerative
-normal CHr
How can the typical anemia of CKD CBC results change if the patient has chronic GI hemorrhage and absolute iron deficiency?
-microcytic
-hypochromic
-decreased CHr
How is anemia of inflammation distinguished from anemia of CKD?
-evaluation of clinical signs of CKD and/or inflammation
-evaluation of plasma chemistry and urinalysis results
How does classic IMHA differ from PIMA?
-classic IMHA targets and destroys mature RBCs in circulation
-PIMA targets and destroys erythroid precursors in the bone marrow
What are the expected CBC findings in PIMA?
-moderate to marked
-normocytic
-normochromic
-non-regenerative anemia
-often no spherocytes or agglutination
What are the expected marrow findings in PIMA?
-ineffective erythropoiesis
-macrophages phagocytizing erythroid precursors
What are the characteristics of FeLV and the blood?
-virus can affect hematologic cells in various ways
-virus can cause a very wide range of hematologic abnormalities of RBCs, WBCs, and/or platelets
What are the characteristics of relative erythrocytosis?
-more common
-total mass of RBCs in the body has not changed
-occurs due to decreased vascular water or release of pooled RBCs from spleen
What are the characteristics of absolute erythrocytosis?
-less common
-total mass of RBCs in the body is increased
-occurs due to increased RBC production by marrow
How does dehydration cause relative erythrocytosis?
decreased plasma water concentrates RBCs in blood
How does epinephrine cause relative erythrocytosis?
splenic contraction releases RBCs pooled in the spleen
How does endotoxemia cause relative erythrocytosis?
damages endothelial cells, allowing plasma water to leak into extravascular space
How does chronic hypoxia cause absolute erythrocytosis?
stimulates increased EPO production by kidneys
How does inappropriate EPO production cause absolute erythrocytosis?
unregulated production of EPO by certain tumor cells
How does primary erythrocytosis cause absolute erythrocytosis?
neoplastic proliferation of erythroid precursors that is independent of EPO
