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Terms in this set (72)
blood is ... % plasma and ... % blood cells
55% plasma, 45% red blood cells
what are the 4 main components of blood?
plasma, red blood cells, white blood cells, and platelets
what are the basic morphologic changes that occur as blood cells mature?
cells decrease in size, nuclei become smaller and darker staining
true or false, hematopoetic stem cells circulate through the blood?
true (ensures continued blood production)
what are the 3 phases in red blood cell production?
ribosome synthesis --> hemoglobin accumulation--> ejection of nucleus
what sort of events will trigger EPO production in the kidney?
hypoxic events i.e. anemia, lung disease, high altitude, shunts, hemorrhage
how many red blood cells are produced by the bone marrow each day?
how are platelets produced from megakaryocytes?
sites of hematopoiesis change with age
starts in blood islands--> bone marrow
how does hematopoiesis change with age?
decreased red cell production
what is the hematocrit?
proportion of blood that consists of packed RBCs; expressed as a percentage by volume
what is the average lifespan of...
RBC = 120 days
platelet = 8 days
what is anisocytosis?
variation in size
what is poikilocytosis?
variation in shape
what are spherocytes?
RBCs with no central pallor, spherical shape
what are schistocytes?
fragmented RBCs (often from mechanical shearing)
what are target cells?
excess membrane causes bulging in the center
why might a bone marrow aspirate be better than a biopsy?
because you can count cells that are difficult to identify in a biopsy (e.g. blasts, plasma cells); also good for assessing maturation/ differentiation
what are the 3 general categories of causes for anemia?
blood loss (most common), decreased production, and increased destruction
what are the most common causes of bleeding/ anemia in the clinical setting?
heavy menstrual periods and digestive or urinary tract bleeds
what are the two main type of anemias?
hypoproliferative (low retic count) and hyperproliferative (high retic count)
what is polycythemia vera?
increased erythropoiesis caused by mutation in receptor or JAK 2 (important for EPO signaling to stem cells in bone marrow)
what are the three types of hypoproliferative anemias?
microcytic, normocytic, and macrocytic
how do you differentiate between microcytic, normocytic, and macrocytic anemia?
MCV; microcytic is MCV < 80, normocytic is 80-100, and macrocytic and >100
what are the causes of microcytic anemia?
iron deficiency (late), anemia of chronic disease (late), thalassemias, lead poisoning, and sideroblastic anemia
what are the causes of non-hemolytic, normocytic anemia?
iron deficiency, anemia of chronic disease, aplastic anemia, and chronic kidney disease
what are the causes of intrinsic hemolytic normocytic anemia?
hereditary spherocytosis, G6PD and pyruvate kinase deficiencies, HbC disease, paroxysmal noctural hemoglobinuria, sickle cell anemia
what are the causes of extrinsic hemolytic normocytic anemia?
auto-immune, micro-angiopathic, macro-angiopathic, and infections
what are the causes of macrocytic anemia?
bone marrow failure, vitamin B12 deficiency, folate deficiency, liver disease, alcoholism
how much iron do we need to eat in a day and how much of that do we absorb?
eat 10 mg, absorb 1 mg (to replace what we excrete each day)
where do we absorb our iron?
what are the two proteins responsible for binding iron and what do they do?
transferrin- transports iron, carries a few ions at a time
ferritin- stores iron, carries up to 4500 ions at a time
what is the role of hepcidin in iron absorption?
produced by macrophages--> stops further iron absorption, signals for macrophages and liver to retain stored iron as ferritin
what are the findings (clinical and lab) associated with iron deficiency anemia?
pallor, fatigue, SOB (not specific); hypochromic microcytic anemia; low retics; low iron/ high iron binding capacity = low saturation (<15%)
what's the most common cause of iron deficiency anemia?
iron loss (GI, urine, intravascular hemolysis)
what is hemochromatosis and what leads to it?
mutation leads to decreased hepcidin--> too much iron is absorbed and stored (because hepcidin can't inactivate ferroportin)--> iron toxicity (cirrhosis, hepato-cellular cancer, diabetes)
what is the treatment for hemochromatosis?
therapeutic phlebotomy or iron chelation (if anemic)
what two things are elevated in B12 and folate deficiency?
homocysteine and methylmalonic acid
what is the supply of B12 and folate (amount/ reserve that is stored normally)?
B12 has a 3-5 year supply in the liver, but folate has 2-4 week supply in the liver
how is B12 absorbed?
need acidic environment to release B12 from proteins, then is absorbed through a receptor for intrinsic factor in the ileum
if someone has a folate deficiency, what do you also need to check and why?
also need to check that they don't have a B12 deficiency, because folate supplementation cannot correct the neurologic deficits caused by a B12 deficiency
bone marrow failure causing normocytic anemia has two main types, what are they?
single cytopenia and agranulocytosis
what are the causes of single cytopenia (type of normocytic anemia)?
generally immunologic suppression, can be associated with thymoma/ lymphoma/ drug/ parvovirus
what are the causes of agranulocytosis (type of normocytic anemia)?
often drug induced
what is aplastic anemia and what is the cause in adults?
lack of stem cells; 90% of cases are caused by AI disease (minority are caused by toxic exposure/ radiation/ drugs)
how do we treat aplastic anemia (for the most part)?
equine anti-thymocyte globulin (kills T cells in the recipient); 80-90% cure rates in one year
what sort of lab tests suggest hemolysis?
indirect bilirubin (elevated) and haptoglobin (decreased with hemolysis)
what are the 3 categories of RBC defects that can cause hemolysis?
membrane proteins, hemoglobin, and glycolytic pathway
what 3 congenital defects affect the RBC cytoskeleton and can result in hemolysis? what are the proteins that can be mutated?
hereditary spherocytosis, hereditary elliptocytosis, and hereditary stomatocytosis; spectrin, ankyrin or band 3 can be mutated
what is the pathophysiology of paroxysmal nocturnal hemoglobinuria?
loss of proteins leads to increased sensitivity to lysis by complement; intravascular hemolysis
what are the two hemoglobin problems that can lead to hemolytic anemia?
sickle cell (abnormal hemoglobin, qualitative) OR thalassemias (abnormal synthesis of normal hemoglobin, quantitative)
how do thalassemias lead to both extramedullary and intramedullary hemolysis?
excess globin chains ppt and bind to RBC membranes--> damage--> removed by RES (extramedullary hemolysis); decreased heme synthesis--> Fe accumulation--> mitochondria toxicity--> RBC death in marrow (intramedullary hemolysis)
what are the findings consistent with B thalassemia minor diagnosis?
microcytosis with normal iron studies; hypochromia and target cells on peripheral blood smear
what is beta thal major?
severe anemia presenting at 3 months; can result in congestive heart failure, bone marrow expansion (skeletal deformities, enlargement of liver and spleen), and iron overload (due to reduced hepcidin production)
what is the characteristic finding on blood smear for beta thalassemia major?
what are the characteristic facial findings associated with beta thalassemia major?
forehead bossing and dental deformities
how can you treat beta thalassemia?
hypertransfusion (reduces excessive RBC production and decreases bone marrow expansion), iron chelation (prevents accumulation in organs), and splenectomy (reduces transfusion requirement)
alpha thalassemia is the most common hemoglobinopathy and is in 30% of what population?
30% of West Africans
hydrops fetalis is the result of...
fetus with NO alpha genes (from parents who were both hetrozygotes for alpha genes)
what is the pathophysiology of sickle cell anemia?
HbS is less soluble--> aggregates--> sickled cells; rigid RBCs occlude small blood vessels--> hypoxia and tissue infarction
when does sickle cell disease present (how old)?
3-6 months (because this is when normal fetal hemoglobin drops out)
patients with sickle cell disease have 10x risk of sudden death because of...
sickle cell is NOT associated with splenomegaly
infarction of spleen at an early age (auto-splenectomy)
what should you give to rehydrate someone with sickle cell?
what is the acute treatment for sickle cell crisis?
hydration with hypotonic fluids, analgesia, oxygen, RBC transfusion, IV immunoglobulin, NO
what is the chronic treatment for sickle cell disease?
hydration (to decrease MCHC), analgesics, folic acid supplementation, immunization, prophylactic antibiotics (no spleen)
why is G6PD deficiency damaging to RBCs?
because there isn't any glutathione available to protect against/ repair oxidative damage
what can exacerbate the symptoms of someone with G6PD deficiency?
infection, drugs (anti-malarials, sulfa drugs), and fava beans
what happens in a direct coomb's test?
patient blood + IgG coombs reagent --> agglutination
what happensin an indirect coomb's test?
put patient serum with RBCs with known antigens
IgM antibodies are (warm or cold) and IgG antibodies are (warm or cold)?
IgM are cold, IgG are warm
what lab findings suggest immune hemolytic anemia?
increased LDH, indirect hyperbilirubinemia, reduced haptoglobin, urinary hemosiderin, hemoglobinuria
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