RBC disorders Flashcards
clinical parameters used in testing for anemia include:
red cell count, hemoglobin concentration, and hematocrit
mechanisms of anemia
blood loss, decreased RBC production, and decreased RBC survival
young, healthy subjects can tolerate rapid loss of _____ of blood with few symptoms, but some will have a ____ response
500-1000 mL (up to 15-20% of total blood volume); vasovagal response (sweating, weakness, nausea, slow HR, and hypotension)
rapid loss of _____ of blood produces shock
2000-2500 mL
the loss of RBCs stimulates increased production, mediated by ____, resulting in an increase in the ____ count in the peripheral blood
erythropoietin; reticulocyte
hemolytic anemias are characterized by _____ and retention of products of ______
shortened RBC survival; RBC destruction (iron)
RBC destruction can occur in the ____ or in the ______
circulation (intravascular hemolysis); reticuloendothelial system (extravascular hemolysis)
a decrease in _____ is a key feature of intravascular hemolysis
serum haptoglobin
extravascular hemolysis involves destruction of RBCs in the reticuloendothelial system including the ____ and ____
spleen; liver
hemolytic anemias are classified by the mechanism of RBC destruction into _____ which are usually inherited and _____ which are usually acquired abnormalities
intrinsic defects ; extrinsic defects
mechanisms of intrinsic defects
membrane defects
abnormal hemoglobin
lack of globin chains
metabolic defect
mechanisms of extrinsic defects
immune destruction
mechanical trauma
infections
a membrane defect is an inherited defect in the RBC membrane that results in _____ of the RBC, so that they are ____ and _____ in the spleen
less deformability; sequestered; destroyed
the specific membrane defect can be a qualitative or quantitative deficiency of ____, a structural protein of the cytoskeleton
spectrin
example of a membrane defect disorder
hereditary spherocytosis (type of extravascular hemolysis)
example of abnormal hemoglobin disorder
sickle cell anemia (extravascular hemolysis)
an inherited defect (autosomal codominant) that results in diminished or absent synthesis of either the alpha or beta globin chains of hemoglobin
thalassemia (extravascular hemolysis)
decreased globin production, as in thalassemia, results in decreased hemoglobin production, and _____ is the principal clinical manifestation
anemia
example of metabolic defect disorder
glucose-6-phosphate dehydrogenase (G6PD) deficiency (extravascular hemolysis)
cytomorphologic hallmark of G6PD deficiency
“bite” cells
this disorder, also called hemolytic disease of the newborn (HDN), is caused by blood group incompatibility between the mother and fetus
erythroblastosis fetalis (extravascular hemolysis)
absorption of vitamin B12 requires _____, a protein produced by ____ of the gastric mucosa
intrinsic factor; parietal cells
IF-B12 complex passes to the _____ where it attaches to receptors on ____ and is absorbed
distal ileum; epithelial cells
the absorbed B12 is bound to ______ in plasma which deliver it to the liver and other cells via the bloodstream
transcobalamins (transport proteins)
folate is absorbed in the _____
proximal small intestine
in aplastic anemia, a ____ abnormality results in marked reduction of ______
stem cell; hematopoiesis
in aplastic anemia, production of all cellular elements of the blood is markedly decreased, which is called _____; aplastic anemia also has markedly decreased _____
pancytopenia; bone marrow cellularity
two major pathogenic theories of aplastic anemia
- an acquired defect in stem cell production (decreased production of all types of blood cells)
- suppression of stem cells by T lymphocytes
caused by autoantibodies to parietal cells and intrinsic factor
pernicious anemia
B12 deficiency is associated with _____
atrophic gastritis
pernicious anemia associated with loss of _____, ____, and _____
gastric parietal cells, achlorhydia, and deficient IF
half of the cases of aplastic anemia are idiopathic and the remainder are caused by ____, ____, or ____
drugs (chloramphenicol), toxins (benzene), viral hepatitis
decreased production of RBCs due to replacement of marrow elements by tumor (metastasis my myeloma) or fibrosis; platelets often also decreased
myelophthistic anemia
the opposite of anemia; an increase in red cell mass
polycythemia
_____ occurs with hemoconcentration from dehydration, vomiting, diarrhea, or excessive use of diuretics; _____ can be a primary or secondary phenomenon
relative polycythemia; absolute polycythemia
stimuli which increase production of _____ can produce secondary absolute polycythemia
erythropoietin
primary absolute polycythemia occurs when there is a non-regulated (neoplastic) proliferation of red cells and myeloid cells, called a _____
polycythemia vera
_____ are helpful in distinguishing primary from secondary cases of absolute polycythemia
erythropoietin levels-
primary (normal or suppressed)
secondary (increased levels)
____ and ____ are two leading causes of ischemia-related death in sickle cell anemia patients
acute chest syndrome and stroke
what is the hallmark of autoimmune hemolytic anemia`
spherocytes
most common cause of anemia worldwide
iron deficiency anemia
in iron deficiency anemia, RBCs become ____ and contain _____ than usual
smaller (microcytic); less hemoglobin (hypochromic)
low MCV and MCHC
